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Casablanca

Casablanca (الدار البيضاء, ) is the largest city in Morocco and the country's economic and business centre. Located on the Atlantic coast of the Chaouia plain in the central-western part of Morocco, the city has a population of about 3.71 million in the urban area, and over 4.27 million in Greater Casablanca, making it the most populous city in the Maghreb region, and the eighth-largest in the Arab world.

Casablanca is Morocco's chief port, with the Port of Casablanca being one of the largest artificial ports in Africa, and the third-largest port in North Africa, after Tanger-Med (40 km east of Tangier) and Port Said. Casablanca also hosts the primary naval base for the Royal Moroccan Navy.

Casablanca is a significant financial centre, ranking 54th globally in the September 2023 Global Financial Centres Index rankings, between Brussels and Rome. The Casablanca Stock Exchange is Africa's third-largest in terms of market capitalization, as of December 2022.

Major Moroccan companies and many of the largest American and European companies operating in the country have their headquarters and main industrial facilities in Casablanca. Recent industrial statistics show that Casablanca is the main industrial zone in the country.

Anfa
Before the 15th century, the settlement at what is now Casablanca had been called Anfa, rendered in European sources variously as El-Anfa, Anafa or Anaffa, Anafe, Anife, Anafee, Nafe, and Nafee. Ibn Khaldun ascribed the name to the Anfaça, a branch of the tribe of the Maghreb, though the sociologist André Adam refuted this claim due to the absence of the third syllable. Nahum Slouschz gave a Hebrew etymology, citing the Lexicon of Gesenius: anâphâh (a type of bird) or anaph (face, figure), though Adam refuted this arguing that even a Judaized population would still have spoken Tamazight. Adam also refuted an Arabic etymology, أنف (anf, "nose"), as the city predated the linguistic Arabization of the country, and the term anf was not used to describe geographic areas. Adam affirmed a Tamazight etymology—from anfa "hill", anfa "promontory on the sea", ifni "sandy beach", or anfa "threshing floor"—although he determined the available information insufficient to establish exactly which.

The name "Anfa" was used in maps until around 1830—in some until 1851—which Adam attributes to the tendency of cartographers to replicate previous maps.

Casablanca
When Sultan Mohammed ben Abdallah (c. 1710–1790) rebuilt the city after its destruction in the earthquake of 1755, it was renamed "ad-Dār al-Bayḍāʾ " (الدار البيضاء The White House), though in vernacular use it was pronounced "Dar al-Baiḍā" (دار البيضاء literally House of the White, although in Moroccan Arabic vernacular it retains the original sense of The White House).

The origins of the name "Casablanca" are unclear, although several theories have been suggested. André Adam mentions the legend of the Sufi saint and merchant Allal al-Qairawani, who supposedly came from Tunisia and settled in Casablanca with his wife Lalla al-Baiḍāʾ (لالة البيضاء White Lady). The villagers of Mediouna would reportedly provision themselves at "Dar al-Baiḍāʾ" (دار البيضاء House of the White).

In fact, on a low hill slightly inland above the ruins of Anfa and just to the west of today's city centre, it appears there was a white-washed structure, possibly a Sufi zawiya that acted as a landmark to sailors. The Portuguese cartographer Duarte Pacheco wrote in the early 16th century that the city could easily be identified by a tower, and nautical guides from the late 19th century still mentioned a "white tower" as a point of reference. The Portuguese mariners calqued the modern Arabic name to "Casa Branca" ( White House) in place of Anfa. The name "Casablanca" was then a calque of the Portuguese name when the Spanish took over trade through the Iberian Union.

During the French protectorate in Morocco, the name remained Casablanca. Today, Moroccans still call the city Casablanca or Casa for short, or by its Arabic name, pronounced in Moroccan Arabic or  in Standard Arabic.

Early history
The area that is today Casablanca was founded and settled by Berbers by the seventh century BC. It was used as a port by the Phoenicians, then the Romans. In his book Description of Africa, Leo Africanus refers to ancient Casablanca as "Anfa", a great city founded in the Berber kingdom of Barghawata in 744 AD. He believed Anfa was the most "prosperous city on the Atlantic Coast because of its fertile land." Barghawata rose as an independent state around this time, and continued until it was conquered by the Almoravids in 1068. After the defeat of the Barghawata in the 12th century, Arab tribes of Hilal and Sulaym descent settled in the region, mixing with the local Berbers, which led to widespread Arabization. During the 14th century, under the Merinids, Anfa rose in importance as a port. The last of the Merinids were ousted by a popular revolt in 1465.

Portuguese conquest and Spanish influence
In the early 15th century, the town became an independent state once again, and emerged as a safe harbour for pirates and privateers. The Portuguese consequently bombarded the town into ruins in 1468. The town that grew up around it was called Casa Branca, meaning "white house" in Portuguese.

The town was finally rebuilt between 1756 and 1790 by Sultan Mohammed ben Abdallah, the grandson of Moulay Ismail and an ally of George Washington, with the help of Spaniards from the nearby emporium. The town was called ad-Dār al-Bayḍāʼ (الدار البيضاء), the Arabic translation of the Portuguese Casa Branca.

Colonial struggle
In the 19th century, the area's population began to grow as it became a major supplier of wool to the booming textile industry in Britain and shipping traffic increased (the British, in return, began importing gunpowder tea, used in Morocco's national drink, mint tea). By the 1860s, around 5,000 residents were there, and the population grew to around 10,000 by the late 1880s. Casablanca remained a modestly sized port, with a population reaching around 12,000 within a few years of the French conquest and arrival of French colonialists in 1906. By 1921, this rose to 110,000, largely through the development of shanty towns.

Bombardment of Casablanca
The Treaty of Algeciras of 1906 formalized French preeminence in Morocco and included three measures that directly impacted Casablanca: that French officers would control operations at the customs office and seize revenue as collateral for loans given by France, that the French holding company La Compagnie Marocaine would develop the port of Casablanca, and that a French-and-Spanish-trained police force would be assembled to patrol the port.

To build the port's breakwater, narrow-gauge track was laid in June 1907 for a small Decauville locomotive to connect the port to a quarry in Roches Noires, passing through the sacred Sidi Belyout graveyard. In resistance to this and the measures of the 1906 Treaty of Algeciras, tribesmen of the Chaouia attacked the locomotive, killing 9 Compagnie Marocaine laborers—3 French, 3 Italians, and 3 Spanish.

In response, the French bombarded the city in August 1907 with multiple gunboats and landed troops inside the town, causing severe damage and killing between 600 and 3,000 Moroccans. Estimates for the total casualties are as high as 15,000 dead and wounded. In the immediate aftermath of the bombardment and the deployment of French troops, the European homes and the Mellah, or Jewish quarter, were sacked, and the latter was also set ablaze.

As Oujda had already been occupied, the bombardment and military invasion of the city opened a western front to the French military conquest of Morocco.

French rule and influence
French control of Casablanca was formalized March 1912 when the Treaty of Fes established the French Protectorat. Under French imperial control, Casablanca became a port of colonial extraction.

Right at the beginning of the twentieth century when Morocco was officially declared a French protectorate, the French decided to shift power to Morocco's coastal areas (i.e. Rabat and Casablanca) at the expense of its interior areas (i.e. Fez and Marrakech). Rabat was made the administrative capital of the country and Casablanca its economic capital.

General Hubert Lyautey assigned the planning of the new colonial port city to Henri Prost. As he did in other Moroccan cities, Prost designed a European ville nouvelle outside the walls of the medina. In Casablanca, he also designed a new "ville indigène" to house Moroccans arriving from other cities.

Europeans formed almost half the population of Casablanca.

A 1937-1938 typhoid fever outbreak was exploited by colonial authorities to justify the appropriation of urban spaces in Casablanca. Moroccans residing in informal housing were cleared out of the center and displaced, notably to Carrières Centrales.

World War II
After Philippe Pétain of France signed the armistice with the Nazis, he ordered French troops in France's colonial empire to defend French territory against any aggressors—Allied or otherwise—applying a policy of "asymmetrical neutrality" in favour of the Germans. French colonists in Morocco generally supported Pétain, while Moroccans tended to favour de Gaulle and the Allies.

Operation Torch, which started on 8 November 1942, was the British-American invasion of French North Africa during the North African campaign of World War II. The Western Task Force, composed of American units led by Major General George S. Patton and Rear Admiral Henry Kent Hewitt, carried out the invasions of Mehdia, Fedhala, and Asfi. American forces captured Casablanca from Vichy control when France surrendered 11 November 1942, but the Naval Battle of Casablanca continued until American forces sank German submarine U-173 on 16 November.

Casablanca was the site of the Nouasseur Air Base, a large American air base used as the staging area for all American aircraft for the European Theatre of Operations during World War II. The airfield has since become Mohammed V International Airport.

Anfa Conference
Casablanca hosted the Anfa Conference (also called the Casablanca Conference) in January 1943. Prime Minister Winston Churchill and President Franklin D. Roosevelt discussed the progress of the war. Also in attendance were the Free France generals Charles de Gaulle and Henri Giraud, though they played minor roles and didn't participate in the military planning.

It was at this conference that the Allies adopted the doctrine of "unconditional surrender", meaning that the Axis powers would be fought until their defeat. Roosevelt also met privately with Sultan Muhammad V and expressed his support for Moroccan independence after the war. This became a turning point, as Moroccan nationalists were emboldened to openly seek complete independence.

Toward independence
During the 1940s and 1950s, Casablanca was a major centre of anti-French rioting.

On 7 April 1947, a massacre of working class Moroccans, carried out by Senegalese Tirailleurs in the service of the French colonial army, was instigated just as Sultan Muhammed V was due to make a speech in Tangier appealing for independence.

Riots in Casablanca took place from 7–8 December 1952, in response to the assassination of the Tunisian labor unionist Farhat Hached by La Main Rouge—the clandestine militant wing of French intelligence. Then, on 25 December 1953 (Christmas Day), Muhammad Zarqtuni orchestrated a bombing of Casablanca's Central Market in response to the forced exile of Sultan Muhammad V and the royal family on 20 August (Eid al-Adha) of that year.

Since independence
Morocco gained independence from France in 1956. The post-independence era witnessed significant urban transformations and socio-economic shifts, particularly in neighborhoods like Hay Mohammadi, which were deeply impacted by neoliberal policies and state-led urban redevelopment projects.

Casablanca Group
On 4–7 January 1961, the city hosted an ensemble of progressive African leaders during the Casablanca Conference of 1961. Among those received by King Muhammad V were Gamal Abd An-Nasser, Kwame Nkrumah, Modibo Keïta, and Ahmed Sékou Touré, Ferhat Abbas.

Jewish emigration
Casablanca was a major departure point for Jews leaving Morocco through Operation Yachin, an operation conducted by Mossad to secretly migrate Moroccan Jews to Israel between November 1961 and spring 1964.

1965 riots
The 1965 student protests organized by the National Union of Popular Forces-affiliated National Union of Moroccan Students, which spread to cities around the country and devolved into riots, started on 22 March 1965, in front of Lycée Mohammed V in Casablanca. The protests started as a peaceful march to demand the right to public higher education for Morocco, but expanded to include concerns of labourers, the unemployed, and other marginalized segments of society, and devolved into vandalism and rioting. The riots were violently repressed by security forces with tanks and armoured vehicles; Moroccan authorities reported a dozen deaths while the UNFP reported more than 1,000.

King Hassan II blamed the events on teachers and parents, and declared in a speech to the nation on 30 March 1965: "There is no greater danger to the State than a so-called intellectual. It would have been better if you were all illiterate."

1981 riots
On 6 June 1981, the Casablanca Bread Riots took place, which were sparked by a sharp increase in the price of necessities such as butter, sugar, wheat flour, and cooking oil following a period of severe drought. Hassan II appointed the French-trained interior minister Driss Basri as hardliner, who would later become a symbol of the Years of Lead, with quelling the protests. The government stated that 66 people were killed and 100 were injured, while opposition leaders put the number of dead at 637, saying that many of these were killed by police and army gunfire.

Mudawana
In March 2000, more than 60 women's groups organized demonstrations in Casablanca proposing reforms to the legal status of women in the country. About 40,000 women attended, calling for a ban on polygamy and the introduction of divorce law (divorce being a purely religious procedure at that time). Although the counter-demonstration attracted half a million participants, the movement for change started in 2000 was influential on King Mohammed VI, and he enacted a new mudawana, or family law, in early 2004, meeting some of the demands of women's rights activists.

Further history
On 16 May 2003, 33 civilians were killed and more than 100 people were injured when Casablanca was hit by a multiple suicide bomb attack carried out by Moroccans and claimed by some to have been linked to al-Qaeda. Twelve suicide bombers struck five locations in the city.

Another series of suicide bombings struck the city in early 2007. These events illustrated some of the persistent challenges the city faces in addressing poverty and integrating disadvantaged neighborhoods and populations. One initiative to improve conditions in the city's disadvantaged neighborhoods was the creation of the Sidi Moumen Cultural Center.

As calls for reform spread through the Arab world in 2011, Moroccans joined in, but concessions by the ruler led to acceptance. However, in December, thousands of people demonstrated in several parts of the city, especially the city center near la Fontaine, desiring more significant political reforms. On 1 November 2023, Casablanca along with Ouarzazate joined UNESCO's Creative Cities Network.

Geography
Casablanca is located on the Atlantic coast of the Chaouia Plains, which have historically been the breadbasket of Morocco. Apart from the Atlantic coast, the Bouskoura forest is the only natural attraction in the city. The forest was planted in the 20th century and consists mostly of eucalyptus, palm, and pine trees. It is located halfway to the city's international airport.

The only watercourse in Casablanca is oued Bouskoura, a small seasonal creek that until 1912 reached the Atlantic Ocean near the actual port. Most of oued Bouskoura's bed has been covered due to urbanization and only the part south of El Jadida road can now be seen. The closest permanent river to Casablanca is Oum Rabia, 70 km to the south-east.

Climate
Casablanca has a hot-summer Mediterranean climate (Köppen climate classification Csa). The cool Canary Current off the Atlantic coast moderates temperature variation, which results in a climate remarkably similar to that of coastal Los Angeles, with similar temperature ranges. The city has an annual average of 72 days with significant precipitation, which amounts to 412 mm per year. The highest and lowest temperatures ever recorded in the city are 40.5 °C and -2.7 °C, respectively. The highest amount of rainfall recorded in a single day is 178 mm on 30 November 2010.

Climate change
A 2019 paper published in PLOS One estimated that under Representative Concentration Pathway 4.5, a "moderate" scenario of climate change where global warming reaches ~2.5-3 C-change by 2100, the climate of Casablanca in the year 2050 would most closely resemble the current climate of Tripoli, Libya. The annual temperature would increase by 1.7 C-change, and the temperature of the warmest month by 1.6 C-change, while the temperature of the coldest month would actually decrease by 0.2 C-change.

Moreover, according to the 2022 IPCC Sixth Assessment Report, Casablanca is one of 12 major African cities (Abidjan, Alexandria, Algiers, Cape Town, Casablanca, Dakar, Dar es Salaam, Durban, Lagos, Lomé, Luanda and Maputo) which would be the most severely affected by future sea level rise. It estimates that they would collectively sustain cumulative damages of US$65 billion under RCP 4.5 and US$86.5 billion for the high-emission scenario RCP 8.5 by the year 2050. Additionally, RCP 8.5 combined with the hypothetical impact from marine ice sheet instability at high levels of warming would involve up to US$137.5 billion in damages, while the additional accounting for the "low-probability, high-damage events" may increase aggregate risks to US$187 billion for the "moderate" RCP4.5, US$206 billion for RCP8.5 and US$397 billion under the high-end ice sheet instability scenario. Since sea level rise would continue for about 10,000 years under every scenario of climate change, future costs of sea level rise would only increase, especially without adaptation measures.

Economy

The Grand Casablanca region is considered the locomotive of the development of the Moroccan economy. It attracts 32% of the country's production units and 56% of industrial labor. The region uses 30% of the national electricity production. With MAD 93 billion, the region contributes to 44% of the industrial production of the kingdom. About 33% of national industrial exports, MAD 27 billion, comes from the Grand Casablanca; 30% of the Moroccan banking network is concentrated in Casablanca.

One of the most important exports of Casablanca is phosphate. Other industries include fishing, fish canning, sawmills, furniture production, building materials, glass, textiles, electronics, leather work, processed food, spirits, soft drinks, and cigarettes.

The Casablanca and Mohammedia seaports activity represent 50% of the international commercial flows of Morocco. Almost the entire Casablanca waterfront is under development, mainly the construction of huge entertainment centres between the port and Hassan II Mosque, the Anfa Resort project near the business, entertainment and living centre of Megarama, the shopping and entertainment complex of Morocco Mall, as well as a complete renovation of the coastal walkway. The Sindbad park was also renewed with rides, games and entertainment services.

Casablanca is a significant financial centre, ranking 54th globally in the September 2023 Global Financial Centres Index rankings, between Brussels and Rome. The Casablanca Stock Exchange is Africa's third-largest in terms of market capitalization, as of December 2022.

Royal Air Maroc has its head office at the previous Casablanca-Anfa Airport location. In 2004, it announced that it was moving its head office from Casablanca to a location in Province of Nouaceur, close to Mohammed V International Airport. The agreement to build the head office in Nouaceur was signed in 2009 but was never implemented.

Administrative divisions
Casablanca is a commune, part of the region of Casablanca-Settat. The commune is divided into eight districts or prefectures, which are themselves divided into 16 subdivisions or arrondissements and one municipality. The districts and their subdivisions are:

 * 1) Aïn Chock (عين الشق) – Aïn Chock (عين الشق)
 * 2) Aïn Sebaâ – Hay Mohammadi (عين السبع الحي المحمدي) – Aïn Sebaâ (عين السبع), Hay Mohammadi (الحي المحمدي), Roches Noires (روش نوار).
 * 3) Anfa (أنفا) – Anfa (أنفا), Maârif (المعاريف), Sidi Belyout (سيدي بليوط).
 * 4) Ben M'Sick (بن مسيك) – Ben M'Sick (بن مسيك), Sbata (سباته).
 * 5) Sidi Bernoussi (سيدي برنوصي) – Sidi Bernoussi (سيدي برنوصي), Sidi Moumen (سيدي مومن).
 * 6) Al Fida – Mers Sultan (الفداء – مرس السلطان) – Al Fida (الفداء); Mechouar (المشور) (municipality), Mers Sultan (مرس السلطان).
 * 7) Hay Hassani (الحي الحسني) – Hay Hassani (الحي الحسني).
 * 8) Moulay Rachid (مولاي رشيد) – Moulay Rachid (مولاي رشيد), Sidi Othmane (سيدي عثمان).

Neighborhoods
The list of neighborhoods is indicative and not complete:

 * 2 Mars
 * Ain Chock
 * Ain Diab
 * Ain Sebaa
 * Attacharouk
 * Belvédère
 * Beauséjour
 * Bouchentouf
 * Bouskoura
 * Bourgogne
 * Californie
 * Centre Ville
 * C.I.L.
 * La Colline
 * Derb Ghallef
 * Derb Sultan
 * Derb Tazi
 * Gauthier
 * Ghandi
 * Habous
 * El Hank
 * Hay Dakhla
 * Hay El Baraka
 * Hay El Hanaa
 * Hay El Hassani
 * Hay El Mohammadi
 * Hay Farah
 * Hay Moulay Rachid
 * Hay Salama
 * Hubous
 * Inara
 * Laimoun (Hay Hassani)
 * Lamkansa
 * Lissasfa
 * Maârif
 * Mers Sultan
 * Nassim
 * Oasis
 * Old Madina
 * Oulfa
 * Palmiers
 * Polo
 * Racine
 * Riviera
 * Roches Noires
 * Salmia 2
 * Sbata
 * Sidi Bernoussi
 * Sidi Maârouf
 * Sidi Moumen
 * Sidi Othmane

Demographics
The commune of Casablanca recorded a population of 3,359,818 in the 2014 Moroccan census. About 98% live in urban areas. Around 25% of the population are under 15 years old, and 9% are over 60 years old. The population of the city is about 11% of the total population of Morocco. Grand Casablanca is the largest urban area in the Maghreb. 99.9% of the population of Morocco are Arab and Berber Muslims. During the French protectorate in Morocco, European Christians formed almost half the population of Casablanca. Since Moroccan independence in 1956, the European population has decreased substantially. The city also is still home to a small community of Moroccan Christians, as well as a small group of foreign Roman Catholic and Protestant residents.

Judaism in Casablanca
Jews have a long history in Casablanca. A Sephardic Jewish community was in Anfa up to the destruction of the city by the Portuguese in 1468. Jews were slow to return to the town, but by 1750, the Rabbi Elijah synagogue was built as the first Jewish synagogue in Casablanca. It was destroyed along with much of the town in the 1755 Lisbon earthquake.

In the mid-19th century, with commercial development through European economic penetration, industrial imports from Europe drove traditional Jewish crafts out of the market, costing many Jews in the interior their traditional livelihoods. Moroccan Jews started migrating from the interior to coastal cities such as Essaouira, Mazagan, Asfi, and later Casablanca for economic opportunity, participating in trade with Europeans and the development of those cities.

Casablanca's mellah was ravaged in the bombardment of Casablanca of 1907, the beginning of the French invasion of Morocco from the West.

Jean-Louis Cohen highlights the role of Jewish patrons in the architecture and urban development of Casablanca, particularly in construction of the overwhelming majority of the city's tallest buildings during the interwar period.  One notable example of this trend is the Lévy-Bendayan Building designed by Marius Boyer.

Approximately 28,000 Moroccan Jews immigrated to the State of Israel between 1948 and 1951, many through Casablanca. Casablanca then became a departure point in Operation Yachin, the covert Mossad-organized migration operation from 1961 to 1964. In 2018 it was estimated that there were only 2,500 Moroccan Jews living in Casablanca, while according to the World Jewish Congress there were only 1,000 Moroccan Jews remaining.

Today, the Jewish cemetery of Casablanca is one of the major cemeteries of the city, and many synagogues remain in service, but the city's Jewish community has dwindled. The Moroccan Jewish Museum is a museum established in the city in 1997.

Colleges and universities
Public:
 * École Centrale Casablanca
 * University of Hassan II Casablanca

Private:

 * HEM Business School
 * Université Mundiapolis
 * Université Internationale de Casablanca

Primary and secondary schools
International schools:

 * Belgium: École Belge de Casablanca
 * French:
 * Collège Anatole France
 * Lycée Lyautey
 * Groupe Scolaire Louis Massignon
 * Lycée La Résidence
 * Lycée Maïmonide (FR)
 * Lycée Léon l'Africain
 * École Normale Hébraïque
 * École Al Jabr
 * Italian: Scuola "Enrico Mattei"
 * Spanish: Instituto Español Juan Ramón Jiménez
 * American:
 * Casablanca American School
 * American Academy Casablanca
 * George Washington Academy
 * Montessori:
 * École Montessori Casablanca

Libraries

 * King Abdul Aziz Foundation for Human Sciences and Islamic Studies
 * Dar America
 * Institut Français
 * Instituto Cervantes
 * Instituto Cervantes

Places of worship
Most of the city's places of worship are Muslim mosques. Some of the city's synagogues, such as Ettedgui Synagogue, also remain. There are also Christian churches; some remain in use — particularly by the West African migrant community — while many of the churches built during the colonial period have been repurposed, such as Church of the Sacred Heart.

Association football
Casablanca is home to two popular football clubs: Wydad Casablanca and Raja Casablanca —which are rivals. Raja's symbol is an eagle and Wydad's symbol is a star and crescent, a symbol of Islam. These two popular clubs have produced some of Morocco's best players, such as: Salaheddine Bassir, Abdelmajid Dolmy, Baddou Zaki, Aziz Bouderbala, and Noureddine Naybet. Other football teams on top of these two major teams based in the city of Casablanca include Rachad Bernoussi, TAS de Casablanca, Majd Al Madina, and Racing Casablanca.

Raja CA, founded in 1949, compete in Botola and play their home games at the Stade Mohammed V. The club is known for their supporters and is one of the most supported teams in Africa. Wydad AC, founded in 1937, also compete in Botola and play their home games at the Stade Mohammed V. Both have a strong reputation on continental competitions, having both won the CAF Champions League three times.

Casablanca hosted eight African Champions League finals, all eight at the Stade Mohammed V. The Stade also hosted the 2018 CHAN Final (which Morocco won) and 1988 African Cup of Nations final. It could potentially host matches for the 2030 FIFA World Cup including the final.

Tennis
Casablanca hosts The Grand Prix Hassan II, a professional men's tennis tournament of the ATP tour. It first began in 1986, and is played on clay courts type at Complexe Al Amal.

Notable winners of the Hassan II Grand-Prix are Thomas Muster in 1990, Hicham Arazi in 1997, Younes El Aynaoui in 2002, and Stanislas Wawrinka in 2010.

Hosting
Casablanca staged the 1961 Pan Arab Games, the 1983 Mediterranean Games, and games during the 1988 Africa Cup of Nations. Morocco was scheduled to host the 2015 African Nations Cup, but decided to decline due to Ebola fears. Morocco was expelled and the tournament was held in Equatorial Guinea. However, Morocco will host the 2025 edition after original host Guinea was stripped from hosting rights due to lack of readiness and preparation delays.

Venues

 * Stade Larbi Zaouli
 * Stade Mohamed V
 * Stade Sidi Bernoussi
 * Complexe Al Amal de Casablanca

The Grand Stade de Casablanca is the proposed title of the planned football stadium to be built in the city. Once completed in 2025, it will be used mostly for football matches and will serve as the home of Raja Casablanca, Wydad Casablanca, and the Morocco national football team. The stadium was designed with a capacity of 93,000 spectators, making it one of the highest-capacity stadiums in Africa. Once completed, it will replace the Stade Mohamed V. The initial idea of the stadium was for the 2010 FIFA World Cup, for which Morocco lost their bid to South Africa. Nevertheless, the Moroccan government supported the decision to go ahead with the plans. It will be completed in 2025. The idea of the stadium was also for the 2026 FIFA World Cup, for which Morocco lost their bid to Canada, Mexico and United States. It will now host the 2030 FIFA World Cup which Morocco will co-host with two European nations Spain and Portugal. It is expected to be complete by 2028.

Road Racing
The city is host to the International Casablanca Marathon, a 26.2-mile road race that draws international competition. The race was founded in 2008 and is a member of the Association of International Marathons and Distance Races.

Music
Haja El Hamdaouia, one of the most iconic figures in aita music, was born in Casablanca. Nass El Ghiwane, led by Larbi Batma, came out of Hay Mohammadi in Casablanca. Naima Samih of Derb Sultan gained prominence through the program Mawahib (مواهب). Abdelhadi Belkhayat and Abdelwahab Doukkali are musicians specializing in traditional Moroccan Arabic popular music. Zina Daoudia, Abdelaziz Stati, Abdellah Daoudi, and Said Senhaji are notable Moroccan chaabi musicians.

Abdelakabir Faradjallah founded Attarazat Addahabia, a Moroccan funk band, in 1968. Fadoul, another funk band, formed in the 1970s.

Hoba Hoba Spirit also formed in Casablanca, and is still based there. Casablanca has a thriving hiphop scene, with artists such as El Grande Toto, Don Big, 7liwa, and Issam Harris.

Casablanca hosts numerous music festivals, such as Jazzablanca and L'Boulevard, as well as a museum dedicated to Andalusi music, Dar ul-Aala.

Literature
Francesco Cavalli's L'Ormindo is a 17th-century Venetian opera set between Anfa and Fes.

The French writer Antoine de Saint-Exupéry is associated with Casablanca.

Driss Chraïbi's novel The Simple Past takes place in Casablanca. Mohamed Zafzaf lived in Maarif while writing and teaching at a high school.

Lamalif, a radical leftist political and cultural magazine, was based in Casablanca.

Casablanca's International Book Fair is held at the fair grounds opposite Hassan II Mosque annually in February.

Theater
Tayeb Saddiki, described as the father of Moroccan theater, grew up in Casablanca and made his career there. Hanane el-Fadili and Hassan El Fad are popular comedians from Casablanca. Gad Elmaleh is another comedian from Casablanca, though he has made his career abroad.

Visual art
The École des Beaux-Arts of Casablanca was founded in 1919 by a French Orientalist painter named Édouard Brindeau de Jarny, who started his career teaching drawing at Lycée Lyautey. The Casablanca School—a Modernist art movement and collective including artists such as Farid Belkahia, Mohamed Melehi, and Mohammed Chabâa—developed out of the École des Beaux-Arts of Casablanca in the late 1960s.

The Academy of Traditional Arts, part of the Hassan II Mosque complex, was founded 31 October 2012.

L'Uzine is a community-based art and culture space in Casablanca.

Rebel Spirit published The Casablanca Guide (الدليل البيضاوي, Le Guide Casablancais) a comic book about life in Casablanca.

Sbagha Bagha is a street art festival during which murals are created on the sides of apartment buildings.

Photography
Postcard companies such as Léon & Lévy were active in Casablanca. Gabriel Veyre also worked and eventually died in Casablanca.

Marcelin Flandrin (1889–1957), a French military photographer, settled in Casablanca and recorded much of the early colonial period in Morocco with his photography. With his staged nude postcard photos taken in Casablanca's colonial brothel quarter, Flandrin was also responsible for disseminating the orientalist image of Moroccan women as sexual objects.

Casablanca has a thriving street photography scene. Yoriyas is prominent among photographers capturing the economic capital's street scenes, and has attracted international attention.

Film
In the first half of the 20th century, Casablanca had many movie theaters, such as Cinema Rialto, Cinema Lynx and Cinema Vox, the largest in Africa when it was built.

The 1942 American film Casablanca is set in Casablanca and has had a lasting impact on the city's image although it was filmed in the United States. Salut Casa! was a propaganda film brandishing France's purported colonial triumph in its mission civilisatrice in the city.

Mostafa Derkaoui's revolutionary independent film About Some Meaningless Events (1974) took place in Casablanca. It was the main subject of Ali Essafi's documentary Before the Dying of the Light.

Love in Casablanca (1991), starring Abdelkarim Derqaoui and Muna Fettou, is one of the first Moroccan films to deal with Morocco's complex realities and to depict life in Casablanca with verisimilitude. Nour-Eddine Lakhmari's Casanegra (2008) depicts the harsh realities of Casablanca's working classes. The films Ali Zaoua (2000), Horses of God (2012), and Razzia (2017) of Nabil Ayouch, a French director of Moroccan heritage, deal with street crime, terrorism and social issues in Casablanca, respectively. The events in Meryem Benm'Barek-Aloïsi's 2018 film Sofia revolve around an illegitimate pregnancy in Casablanca. Ahmed El Maanouni, Hicham Lasri and Said Naciri are also from Casablanca.

Architecture
Casablanca's architecture and urban development are historically significant. The city is home to many notable buildings in a variety of styles, including traditional Moroccan architecture, various colonial architectural styles, Art Nouveau, Art Deco, Neo-Mauresque, Streamline Moderne, Modernism, Brutalism, and more. During the French Protectorate, the French government described Casablanca as a "laboratory of urbanism".

The work of the Groupe des Architectes Modernes Marocains (GAMMA) on public housing projects—such as Carrières Centrales in Hay Mohammadi—in a style described as vernacular modernism influenced modernist architecture around the world.

Casamémoire and MAMMA. are two organizations dedicated to the preservation and appreciation of the city's architectural heritage.

Rapid transit
The Casablanca Tramway is the rapid transit tram system in Casablanca. As of 2019, the network consists of two lines covering 47.5 km, with 71 stops; further lines (T3 and T4) are under construction.

Casablanca is also planning to introduce a rapid bus network called the Casablanca Busway. The network will consist of two lines, BW1 and BW2. As of October 2023, the system was operating in a testing phase and its public opening, initially planned for July 2023, was delayed due to technical problems.

Since the 1970s, Casablanca had planned to build a metro system to offer some relief to the problems of traffic congestion and poor air quality. However, the city council voted to abandon the metro project in 2014 due to high costs, and decided to continue expanding the already operating tram system instead.

Air
Casablanca's main airport is Mohammed V International Airport, Morocco's busiest airport. Regular domestic flights serve Marrakech, Rabat, Agadir, Oujda, Tangier, Al Hoceima, and Laayoune, as well as other cities.

Casablanca is well-served by international flights to Europe, especially French and Spanish airports, and has regular connections to North American, Middle Eastern and sub-Saharan African destinations. New York City, Montreal, Paris, Washington D.C., London and Dubai are important primary destinations.

The older, smaller Casablanca-Anfa Airport to the west of the city, served certain destinations including Damascus and Tunis, and was largely closed to international civilian traffic in 2006. It was eventually demolished to make way for construction of the "Casablanca Finance City", the new heart of the city of Casablanca. Casablanca Tit Mellil Airport is located in the nearby community of Tit Mellil.

Coach buses
Compagnie de Transports au Maroc (CTM) offers private intercity coach buses on various lines run servicing most notable Moroccan towns, as well as a number of European cities. These run from the CTM Bus Station on Leo Africanus Street near the Central Market in downtown Casablanca. Supratours, an affiliate of ONCF, also offers coach bus service at a slightly lower cost, departing from a station on Wilad Zian Street. There is another bus station farther down on the same street called the Wilad Zian Bus Station; this station is the country's largest bus station, serving over 800 buses daily, catering more to Morocco's lower income population.

Taxis
Registered taxis in Casablanca are coloured red and known as petits taxis (small taxis), or coloured white and known as grands taxis (big taxis). As is standard Moroccan practice, petits taxis, typically small-four door Dacia Logan, Peugeot 207, or similar cars, provide metered cab service in the central metropolitan areas. Grands taxis, generally older Mercedes-Benz sedans, provide shared mini-bus like service within the city on predefined routes, or shared intercity service. Grands taxis may also be hired for private service by the hour or day.

Trains
Casablanca is served by three main railway stations run by the national rail service, the ONCF.

Casa-Voyageurs is the main intercity station, from which trains run south to Marrakech or El Jadida and north to Mohammedia and Rabat, and then on either to Tangier or Meknes, Fes, Taza and Oujda/Nador. It also serves as the southern terminus of the Al-Boraq high speed line from Tangier. A dedicated airport shuttle service to Mohammed V International Airport also has its primary in-city stop at this station, for connections on to further destinations. Casa-Port serves primarily commuter trains such as the Train Navette Rapide (TNR or Aouita) operating on the Casablanca – Kenitra rail corridor, with some connecting trains running on to Gare de Casa-Voyageurs. The station provides a direct interchange between train and shipping services, and is located near several port-area hotels. It is the nearest station to the old town of Casablanca, and to the modern city centre, around the landmark Casablanca Twin Center. Casa-Port station is being rebuilt in a modern and enlarged configuration. During the construction, the station is still operational. From 2013, it will provide a close connection from the rail network to the city's new tram network.

Casa-Oasis was originally a suburban commuter station which was fully redesigned and rebuilt in the early 21st century, and officially reopened in 2005 as a primary city rail station. Owing to its new status, all southern intercity train services to and from Casa-Voyageurs now call at Casa-Oasis. ONCF stated in 2005 that the refurbishment and upgrading of Casa-Oasis to intercity standards was intended to relieve passenger congestion at Casa-Voyageurs station.

Tourism
Although Mohammed V International Airport receives most international flights into Morocco, international tourism in Casablanca is not as developed as it is in cities such as Fes and Marrakech.

The Hassan II Mosque, which is the second largest mosque in Africa and the seventh-largest in the world, is the city's main tourist attraction. Visitors also come to see the city's rich architectural heritage.

Popular sites for national tourism include shopping centers such as Morocco Mall, Anfa Place, the Marina Shopping Center, and the Tachfine Center. Additional sites include the Corniche and the beach of Ain Diab, and parks such as the Arab League Park or the Sindibad theme park.

Notable people

 * Lahcen Abrami – former Moroccan footballer
 * Amine Atouchi – Moroccan footballer
 * Khalil Azmi – former Moroccan goalkeeper
 * Amal Ayouch Moroccan stage and film actress
 * Wissam Baraka – Moroccan footballer
 * Salaheddine Bassir – Moroccan footballer
 * Laarbi Batma – Moroccan musician and artist, founding member of Nas El Ghiwan
 * Larbi Benbarek – Moroccan footballer
 * Badr Benoun – Moroccan footballer
 * Miriem Bensalah-Chaqroun – Moroccan businesswoman
 * Jean-Paul Bertrand-Demanes – French footballer
 * Frida Boccara – French singer, winner of the Eurovision Song Contest 1969
 * Aziz Bouderbala – former Moroccan footballer
 * Merieme Chadid – Moroccan astronomer
 * Mustapha Chadili – former goalkeeper
 * Achraf Dari – Moroccan footballer
 * Jean-Charles de Castelbajac – Moroccan/French fashion designer
 * Nabil Dirar – Moroccan footballer
 * Abdelmajid Dolmy – former Moroccan footballer
 * Dizzy DROS – Moroccan rapper
 * Issam El Adoua – Moroccan footballer
 * Badr El Kaddouri – former Moroccan footballer
 * Talal El Karkouri – former Moroccan footballer
 * Gad Elmaleh – French/Canadian/Moroccan comedian
 * Bouchaib El Moubarki – former Moroccan footballer
 * Youssef Fertout – Moroccan manager
 * La Fouine – Moroccan/French rapper
 * Khalid Fouhami – former Moroccan goalkeeper
 * Mohamed Fouzair – Moroccan footballer
 * Divina Frau-Meigs – Moroccan sociologist and professor
 * El Haqed – Moroccan rapper
 * Serge Haroche – French physicist, awarded the 2012 Nobel Prize for Physics
 * Shatha Hassoun – Moroccan/Iraqi singer
 * Lydia Hatuel-Czuckermann – Israeli Olympic fencer
 * Mouhcine Iajour – Moroccan footballer
 * Driss Joumad – former Morocco international footballer
 * Nadir Lamyaghri – former Moroccan goalkeeper
 * Hamza Mendyl – Moroccan footballer
 * Hicham Mesbahi – Moroccan boxer
 * French Montana – Moroccan/American rapper
 * Nawal El Moutawakel – Moroccan Olympic champion
 * Hakim Mouzaki – Moroccan footballer
 * Abderrahim Najah – Moroccan international basketball player
 * Noureddine Naybet – Moroccan footballer
 * Mostafa Nissaboury – Moroccan poet
 * Hakim Noury – Moroccan film director
 * Maurice Ohana – French composer
 * Faouzia Ouihya – Moroccan-Canadian singer
 * Azzedine Ounahi- Moroccan footballer
 * Jean Reno – Hollywood actor
 * Youssef Rossi – former Moroccan footballer
 * Abdelilah Saber – Moroccan former footballer
 * Youssef Safri – Moroccan football manager
 * Jamal Sellami – Moroccan football manager
 * Daniel Sivan – Israeli professor
 * Alain Souchon – French songwriter
 * Frank Stephenson – Moroccan/British/American award-winning automobile designer
 * Hassan Saada – Moroccan boxer arrested for alleged rape before Olympic match
 * Sidney Taurel – naturalized American CEO of Eli Lilly and Company from 1998 to 2008
 * Richard Virenque – French cyclist
 * Muhammad Zarqtuni – Moroccan nationalist and resistance leader
 * Abdallah Zrika – Moroccan poet

In popular culture

 * The 1942 film Casablanca (starring Ingrid Bergman and Humphrey Bogart) is supposed to have been set in Casablanca, although it was filmed entirely in Los Angeles and does not feature a single Arab or North African character with a speaking role. The film depicts Casablanca as the scene of power struggle between various foreign powers, which had much more to do with the Tangier of the time. The film has achieved worldwide popularity since its release. Nominated for eight Academy Awards, it won three, including Best Picture.
 * A Night in Casablanca (1946) was the 12th Marx Brothers' movie. The film stars Groucho Marx, Chico Marx, and Harpo Marx. It was directed by Archie Mayo and written by Joseph Fields and Roland Kibbee. The film contains the song "Who's Sorry Now?", with music by Ted Snyder and lyrics by Bert Kalmar and Harry Ruby. It is sung in French by Lisette Verea playing the part of Beatrice Rheiner, and then later sung in English. Liszt's "Hungarian Rhapsody No. 2" is played twice, once by Chico on piano as an introduction to the "Beer Barrel Polka", and again by Harpo on the harp.
 * The city is featured in The Mysterious Caravan (1975), volume 54 in the original Hardy Boys series.
 * Casablanca is the setting for several chapters in Doubleshot, a 2000 James Bond novel by Raymond Benson. In the novel, one of the characters mentions that the 1942 film was shot in Hollywood and not on location.
 * Casablanca is one of the key locations in the 2006 video game Dreamfall, as it is where the primary protagonist of the game, Zoë Castillo, lives. Although the city is imagined in the year 2219, much of the present-day architecture is used for inspiration.
 * Casablanca is the setting for the first act of the 2016 World War II romantic thriller film Allied starring Brad Pitt and Marion Cotillard.

Twin towns – sister cities
Casablanca is twinned with:

 * 🇫🇷 Bordeaux, France
 * 🇰🇷 Busan, South Korea
 * 🇺🇸 Chicago, United States
 * 🇸🇳 Dakar, Senegal
 * Dubai, United Arab Emirates
 * 🇮🇩 Jakarta, Indonesia
 * 🇲🇾 Kuala Lumpur, Malaysia
 * 🇴🇲 Muscat, Oman
 * Nouadhibou, Mauritania
 * 🇨🇳 Shanghai, China

Casablanca also has cooperation agreements with:

 * Abuja, Nigeria
 * 🇯🇴 Amman, Jordan
 * Amsterdam, Netherlands
 * 🇪🇸 Barcelona, Spain
 * 🇦🇷 Buenos Aires, Argentina
 * 🇵🇸 Hebron, Palestine
 * 🇹🇷 Istanbul, Turkey
 * 🇰🇪 Kajiado, Kenya
 * 🇧🇫 Koudougou, Burkina Faso
 * 🇨🇦 Montreal, Canada
 * 🇰🇲 Moroni, Comoros
 * Nouakchott, Mauritania
 * 🇫🇷 Paris, France
 * 🇵🇸 Ramallah, Palestine
 * Rotterdam, Netherlands
 * 🇧🇪 Brussels, Belgium
 * 🇪🇸 Madrid, Spain
 * 🇬🇧 London, United Kingdom
 * 🇪🇸 San Sebastián, Spain

 * 🇷🇴 Bucharest, Roumania

title: Casablanca


text:
Cross

A cross is a geometrical figure consisting of two intersecting lines or bars, usually perpendicular to each other. The lines usually run vertically and horizontally. A cross of oblique lines, in the shape of the Latin letter X, is termed a saltire in heraldic terminology.

The cross has been widely recognized as a symbol of Christianity from an early period in that religion's history. Before then, it was used as a religious or cultural symbol throughout Europe, in western and south Asia (the latter, in the form of the original Swastika); and in Egypt, where the Ankh was a hieroglyph that represented "life" and was used in the worship of the god Aten. The effigy of a man hanging on a cross was set up in the fields to protect the crops. It often appeared in conjunction with the female-genital circle or oval, to signify the sacred marriage, as in Egyptian amulet Nefer with male cross and female orb, considered as an amulet of blessedness, a charm of sexual harmony.

Name
The word cross is recorded in 11th-century Old English as cros, exclusively for the instrument of Christ's crucifixion, replacing the native Old English word rood. The word's history is complicated; it appears to have entered English from Old Irish, possibly via Old Norse, ultimately from the Latin (or its accusative crucem and its genitive crucis), "stake, cross". The English verb to cross arises from the noun c. 1200, first in the sense "to make the sign of the cross"; the generic meaning "to intersect" develops in the 15th century. The Latin word was influenced by popular etymology by a native Germanic word reconstructed as *krukjo (English crook, Old English crycce, Old Norse krokr, Old High German krucka). This word, by conflation with Latin crux, gave rise to Old French crocier (modern French ), the term for a shepherd's crook, adopted in English as crosier.

Latin crux referred to the gibbet where criminals were executed, a stake or pole, with or without, on which the condemned were impaled or hanged, but more particularly a cross or the pole of a carriage. The derived verb means "to put to death on the cross" or, more frequently, "to put to the rack, to torture, torment", especially in reference to mental troubles. In the Roman world, furca replaced crux as the name of some cross-like instruments for lethal and temporary punishment, ranging from a forked cross to a gibbet or gallows.

The field of etymology is of no help in any effort to trace a supposed original meaning of crux. A crux can be of various shapes: from a single beam used for impaling or suspending (crux simplex) to the various composite kinds of cross (crux compacta) made from more beams than one. The latter shapes include not only the traditional †-shaped cross (the crux immissa), but also the T-shaped cross (the crux commissa or tau cross), which the descriptions in antiquity of the execution cross indicate as the normal form in use at that time, and the X-shaped cross (the crux decussata or saltire).

The Greek equivalent of Latin crux "stake, gibbet" is stauros, found in texts of four centuries or more before the gospels and always in the plural number to indicate a stake or pole. From the first century BC, it is used to indicate an instrument used in executions. The Greek word is used in descriptions in antiquity of the execution cross, which indicate that its normal shape was similar to the Greek letter tau (Τ).

Pre-Christian

Due to the simplicity of the design (two intersecting lines), cross-shaped incisions make their appearance from deep prehistory; as petroglyphs in European cult caves, dating back to the beginning of the Upper Paleolithic, and throughout prehistory to the Iron Age. Also of prehistoric age are numerous variants of the simple cross mark, including the crux gammata with curving or angular lines, and the Egyptian crux ansata with a loop.

Speculation has associated the cross symbol – even in the prehistoric period – with astronomical or cosmological symbology involving "four elements" (Chevalier, 1997) or the cardinal points, or the unity of a vertical axis mundi or celestial pole with the horizontal world (Koch, 1955). Speculation of this kind became especially popular in the mid- to late-19th century in the context of comparative mythology seeking to tie Christian mythology to ancient cosmological myths. Influential works in this vein included G. de Mortillet (1866), L. Müller (1865), W. W. Blake (1888), Ansault (1891), etc.

In the European Bronze Age the cross symbol appeared to carry a religious meaning, perhaps as a symbol of consecration, especially pertaining to burial.

The cross sign occurs trivially in tally marks, and develops into a number symbol independently in the Roman numerals (X "ten"), the Chinese rod numerals (十 "ten") and the Brahmi numerals ("four", whence the numeral 4).

In the Phoenician alphabet and derived scripts, the cross symbol represented the phoneme /t/, i.e. the letter taw, which is the historical predecessor of Latin T. The letter name taw means "mark", presumably continuing the Egyptian hieroglyph "two crossed sticks" (Gardiner Z9).

Post-Christian

The shape of the cross (crux, stauros "stake, gibbet"), as represented by the letter T, came to be used as a new symbol (seal) or logo of the Early Christianity since the 2nd century in aftermath of its separation from the Second Temple Judaism. Clement of Alexandria in the early 3rd century calls it τὸ κυριακὸν σημεῖον ("the Lord's sign") he repeats the idea, current as early as the Epistle of Barnabas, that the number 318 (in Greek numerals, ΤΙΗ) in Genesis 14:14 was a foreshadowing (a "type") of the cross (the letter Tau) and of Jesus (the letters Iota Eta). Clement's contemporary Tertullian rejects the accusation that Christians are crucis religiosi (i.e. "adorers of the gibbet"), and returns the accusation by likening the worship of pagan idols to the worship of poles or stakes. In his book De Corona, written in 204, Tertullian tells how it was already a tradition for Christians to trace repeatedly on their foreheads the sign of the cross.

While early Christians used the T-shape to represent the cross in writing and gesture, the use of the Greek cross and Latin cross, i.e. crosses with intersecting beams, appears in Christian art towards the end of Late Antiquity. An early example of the cruciform halo, used to identify Christ in paintings, is found in the Miracles of the Loaves and Fishes mosaic of Sant'Apollinare Nuovo, Ravenna (6th century). The Patriarchal cross, a Latin cross with an additional horizontal bar, first appears in the 10th century. A wide variation of cross symbols is introduced for the purposes of heraldry beginning in the age of the Crusades.

Marks and graphemes
The cross mark is used to mark a position, or as a check mark, but also to mark deletion. Derived from Greek Chi are the Latin letter X, Cyrillic Kha and possibly runic Gyfu.

Egyptian hieroglyphs involving cross shapes include ankh "life",  ndj "protect" and nfr "good; pleasant, beautiful".

Sumerian cuneiform had a simple cross-shaped character, consisting of a horizontal and a vertical wedge (𒈦), read as maš "tax, yield, interest"; the superposition of two diagonal wedges results in a decussate cross (𒉽), read as pap "first, pre-eminent" (the superposition of these two types of crosses results in the eight-pointed star used as the sign for "sky" or "deity" (𒀭), DINGIR). The cuneiform script has other, more complex, cruciform characters, consisting of an arrangement of boxes or the fourfold arrangement of other characters, including the archaic cuneiform characters LAK-210, LAK-276, LAK-278, LAK-617 and the classical sign EZEN (𒂡).

Phoenician tāw is still cross-shaped in Paleo-Hebrew alphabet and in some Old Italic scripts (Raetic and Lepontic), and its descendant T becomes again cross-shaped in the Latin minuscule t. The plus sign (+) is derived from Latin t via a simplification of a ligature for et "and" (introduced by Johannes Widmann in the late 15th century).

The letter Aleph is cross-shaped in Aramaic and paleo-Hebrew.

Egyptian hieroglyphs with cross-shapes include Gardiner Z9 – Z11 ("crossed sticks", "crossed planks").

Other, unrelated cross-shaped letters include Brahmi ka (predecessor of the Devanagari letter क) and Old Turkic (Orkhon) d² and Old Hungarian b, and Katakana ナ na and メme.

The multiplication sign (×), often attributed to William Oughtred (who first used it in an appendix to the 1618 edition of John Napier's Descriptio) apparently had been in occasional use since the mid 16th century.

Other typographical symbols resembling crosses include the dagger or obelus (†), the Chinese (十, Kangxi radical 24) and Roman (X ten).

Unicode has a variety of cross symbols in the "Dingbat" block (U+2700–U+27BF):

The Miscellaneous Symbols block (U+2626 to U+262F) adds three specific Christian cross variants, viz. the Patriarchal cross (☦), Cross of Lorraine (☨) and Cross potent (☩, mistakenly labeled a "Cross of Jerusalem").

Emblems
The following is a list of cross symbols, except for variants of the Christian cross and Heraldic crosses, for which see the dedicated lists at Christian cross variants and Crosses in heraldry, respectively.

 * As a design element

Physical gestures
Cross shapes are made by a variety of physical gestures. Crossing the fingers of one hand is a common invocation of the symbol. The sign of the cross associated with Christian genuflection is made with one hand: in Eastern Orthodox tradition the sequence is head-heart-right shoulder-left shoulder, while in Oriental Orthodox, Catholic and Anglican tradition the sequence is head-heart-left-right.

Crossing the index fingers of both hands represents and a charm against evil in European folklore. Other gestures involving more than one hand include the "cross my heart" movement associated with making a promise and the Tau shape of the referee's "time out" hand signal.

Crossed index fingers represent the number 10 (十) in Chinese number gestures.

Unicode
Unicode provides various cross symbols:

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Cross


text:
Coordination complex

A coordination complex is a chemical compound consisting of a central atom or ion, which is usually metallic and is called the coordination centre, and a surrounding array of bound molecules or ions, that are in turn known as ligands or complexing agents. Many metal-containing compounds, especially those that include transition metals (elements like titanium that belong to the periodic table's d-block), are coordination complexes.

Nomenclature and terminology
Coordination complexes are so pervasive that their structures and reactions are described in many ways, sometimes confusingly. The atom within a ligand that is bonded to the central metal atom or ion is called the donor atom. In a typical complex, a metal ion is bonded to several donor atoms, which can be the same or different. A polydentate (multiple bonded) ligand is a molecule or ion that bonds to the central atom through several of the ligand's atoms; ligands with 2, 3, 4 or even 6 bonds to the central atom are common. These complexes are called chelate complexes; the formation of such complexes is called chelation, complexation, and coordination.

The central atom or ion, together with all ligands, comprise the coordination sphere. The central atoms or ion and the donor atoms comprise the first coordination sphere.

Coordination refers to the "coordinate covalent bonds" (dipolar bonds) between the ligands and the central atom. Originally, a complex implied a reversible association of molecules, atoms, or ions through such weak chemical bonds. As applied to coordination chemistry, this meaning has evolved. Some metal complexes are formed virtually irreversibly and many are bound together by bonds that are quite strong.

The number of donor atoms attached to the central atom or ion is called the coordination number. The most common coordination numbers are 2, 4, and especially 6. A hydrated ion is one kind of a complex ion (or simply a complex), a species formed between a central metal ion and one or more surrounding ligands, molecules or ions that contain at least one lone pair of electrons.

If all the ligands are monodentate, then the number of donor atoms equals the number of ligands. For example, the cobalt(II) hexahydrate ion or the hexaaquacobalt(II) ion [Co(H2O)6]2+ is a hydrated-complex ion that consists of six water molecules attached to a metal ion Co. The oxidation state and the coordination number reflect the number of bonds formed between the metal ion and the ligands in the complex ion. However, the coordination number of Pt(en)$2+ 2$ is 4 (rather than 2) since it has two bidentate ligands, which contain four donor atoms in total.

Any donor atom will give a pair of electrons. There are some donor atoms or groups which can offer more than one pair of electrons. Such are called bidentate (offers two pairs of electrons) or polydentate (offers more than two pairs of electrons). In some cases an atom or a group offers a pair of electrons to two similar or different central metal atoms or acceptors—by division of the electron pair—into a three-center two-electron bond. These are called bridging ligands.

History
Coordination complexes have been known since the beginning of modern chemistry. Early well-known coordination complexes include dyes such as Prussian blue. Their properties were first well understood in the late 1800s, following the 1869 work of Christian Wilhelm Blomstrand. Blomstrand developed what has come to be known as the complex ion chain theory. In considering metal amine complexes, he theorized that the ammonia molecules compensated for the charge of the ion by forming chains of the type [(NH3)X]X+, where X is the coordination number of the metal ion. He compared his theoretical ammonia chains to hydrocarbons of the form (CH2)X.

Following this theory, Danish scientist Sophus Mads Jørgensen made improvements to it. In his version of the theory, Jørgensen claimed that when a molecule dissociates in a solution there were two possible outcomes: the ions would bind via the ammonia chains Blomstrand had described or the ions would bind directly to the metal.

It was not until 1893 that the most widely accepted version of the theory today was published by Alfred Werner. Werner's work included two important changes to the Blomstrand theory. The first was that Werner described the two possibilities in terms of location in the coordination sphere. He claimed that if the ions were to form a chain, this would occur outside of the coordination sphere while the ions that bound directly to the metal would do so within the coordination sphere. In one of his most important discoveries however Werner disproved the majority of the chain theory. Werner discovered the spatial arrangements of the ligands that were involved in the formation of the complex hexacoordinate cobalt. His theory allows one to understand the difference between a coordinated ligand and a charge balancing ion in a compound, for example the chloride ion in the cobaltammine chlorides and to explain many of the previously inexplicable isomers.

In 1911, Werner first resolved the coordination complex hexol into optical isomers, overthrowing the theory that only carbon compounds could possess chirality.

Structures
The ions or molecules surrounding the central atom are called ligands. Ligands are classified as L or X (or a combination thereof), depending on how many electrons they provide for the bond between ligand and central atom. L ligands provide two electrons from a lone electron pair, resulting in a coordinate covalent bond. X ligands provide one electron, with the central atom providing the other electron, thus forming a regular covalent bond. The ligands are said to be coordinated to the atom. For alkenes, the pi bonds can coordinate to metal atoms. An example is ethylene in the complex [PtCl3(C2H4)]- (Zeise's salt).

Geometry
In coordination chemistry, a structure is first described by its coordination number, the number of ligands attached to the metal (more specifically, the number of donor atoms). Usually one can count the ligands attached, but sometimes even the counting can become ambiguous. Coordination numbers are normally between two and nine, but large numbers of ligands are not uncommon for the lanthanides and actinides. The number of bonds depends on the size, charge, and electron configuration of the metal ion and the ligands. Metal ions may have more than one coordination number.

Typically the chemistry of transition metal complexes is dominated by interactions between s and p molecular orbitals of the donor-atoms in the ligands and the d orbitals of the metal ions. The s, p, and d orbitals of the metal can accommodate 18 electrons (see 18-Electron rule). The maximum coordination number for a certain metal is thus related to the electronic configuration of the metal ion (to be more specific, the number of empty orbitals) and to the ratio of the size of the ligands and the metal ion. Large metals and small ligands lead to high coordination numbers, e.g. [Mo(CN)8](4-). Small metals with large ligands lead to low coordination numbers, e.g. Pt[P(CMe3)]2. Due to their large size, lanthanides, actinides, and early transition metals tend to have high coordination numbers.

Most structures follow the points-on-a-sphere pattern (or, as if the central atom were in the middle of a polyhedron where the corners of that shape are the locations of the ligands), where orbital overlap (between ligand and metal orbitals) and ligand-ligand repulsions tend to lead to certain regular geometries. The most observed geometries are listed below, but there are many cases that deviate from a regular geometry, e.g. due to the use of ligands of diverse types (which results in irregular bond lengths; the coordination atoms do not follow a points-on-a-sphere pattern), due to the size of ligands, or due to electronic effects (see, e.g., Jahn–Teller distortion):

 * Linear for two-coordination
 * Trigonal planar for three-coordination
 * Tetrahedral or square planar for four-coordination
 * Trigonal bipyramidal for five-coordination
 * Octahedral for six-coordination
 * Pentagonal bipyramidal for seven-coordination
 * Square antiprismatic for eight-coordination
 * Tricapped trigonal prismatic for nine-coordination

The idealized descriptions of 5-, 7-, 8-, and 9- coordination are often indistinct geometrically from alternative structures with slightly differing L-M-L (ligand-metal-ligand) angles, e.g. the difference between square pyramidal and trigonal bipyramidal structures.

 * Square pyramidal for five-coordination
 * Capped octahedral or capped trigonal prismatic for seven-coordination
 * Dodecahedral or bicapped trigonal prismatic for eight-coordination
 * Capped square antiprismatic for nine-coordination

To distinguish between the alternative coordinations for five-coordinated complexes, the τ geometry index was invented by Addison et al. This index depends on angles by the coordination center and changes between 0 for the square pyramidal to 1 for trigonal bipyramidal structures, allowing to classify the cases in between. This system was later extended to four-coordinated complexes by Houser et al. and also Okuniewski et al.

In systems with low d electron count, due to special electronic effects such as (second-order) Jahn–Teller stabilization, certain geometries (in which the coordination atoms do not follow a points-on-a-sphere pattern) are stabilized relative to the other possibilities, e.g. for some compounds the trigonal prismatic geometry is stabilized relative to octahedral structures for six-coordination.

 * Bent for two-coordination
 * Trigonal pyramidal for three-coordination
 * Trigonal prismatic for six-coordination

Isomerism
The arrangement of the ligands is fixed for a given complex, but in some cases it is mutable by a reaction that forms another stable isomer.

There exist many kinds of isomerism in coordination complexes, just as in many other compounds.

Stereoisomerism
Stereoisomerism occurs with the same bonds in distinct orientations. Stereoisomerism can be further classified into:

Cis–trans isomerism and facial–meridional isomerism
Cis–trans isomerism occurs in octahedral and square planar complexes (but not tetrahedral). When two ligands are adjacent they are said to be cis, when opposite each other, trans. When three identical ligands occupy one face of an octahedron, the isomer is said to be facial, or fac. In a fac isomer, any two identical ligands are adjacent or cis to each other. If these three ligands and the metal ion are in one plane, the isomer is said to be meridional, or mer. A mer isomer can be considered as a combination of a trans and a cis, since it contains both trans and cis pairs of identical ligands.

Optical isomerism
Optical isomerism occurs when a complex is not superimposable with its mirror image. It is so called because the two isomers are each optically active, that is, they rotate the plane of polarized light in opposite directions. In the first molecule shown, the symbol Λ (lambda) is used as a prefix to describe the left-handed propeller twist formed by three bidentate ligands. The second molecule is the mirror image of the first, with the symbol Δ (delta) as a prefix for the right-handed propeller twist. The third and fourth molecules are a similar pair of Λ and Δ isomers, in this case with two bidentate ligands and two identical monodentate ligands.

Structural isomerism
Structural isomerism occurs when the bonds are themselves different. Four types of structural isomerism are recognized: ionisation isomerism, solvate or hydrate isomerism, linkage isomerism and coordination isomerism.
 * 1) Ionisation isomerism – the isomers give different ions in solution although they have the same composition. This type of isomerism occurs when the counter ion of the complex is also a potential ligand. For example, pentaamminebromocobalt(III) sulphate [Co(NH3)5Br]SO4 is red violet and in solution gives a precipitate with barium chloride, confirming the presence of sulphate ion, while pentaamminesulphatecobalt(III) bromide [Co(NH3)5SO4]Br is red and tests negative for sulphate ion in solution, but instead gives a precipitate of AgBr with silver nitrate.
 * 2) Solvate or hydrate isomerism – the isomers have the same composition but differ with respect to the number of molecules of solvent that serve as ligand vs simply occupying sites in the crystal. Examples: [Cr(H2O)6]Cl3 is violet colored, [CrCl(H2O)5]Cl2·H2O is blue-green, and [CrCl2(H2O)4]Cl*2H2O is dark green. See water of crystallization.
 * 3) Linkage isomerism occurs with ligands with more than one possible donor atom, known as ambidentate ligands. For example, nitrite can coordinate through O or N. One pair of nitrite linkage isomers have structures (NH3)5CoNO2(2+) (nitro isomer) and (NH3)5CoONO(2+) (nitrito isomer).
 * 4) Coordination isomerism – this occurs when both positive and negative ions of a salt are complex ions and the two isomers differ in the distribution of ligands between the cation and the anion. For example, [Co(NH3)6][Cr(CN)6] and [Cr(NH3)6][Co(CN)6].

Electronic properties
Many of the properties of transition metal complexes are dictated by their electronic structures. The electronic structure can be described by a relatively ionic model that ascribes formal charges to the metals and ligands. This approach is the essence of crystal field theory (CFT). Crystal field theory, introduced by Hans Bethe in 1929, gives a quantum mechanically based attempt at understanding complexes. But crystal field theory treats all interactions in a complex as ionic and assumes that the ligands can be approximated by negative point charges.

More sophisticated models embrace covalency, and this approach is described by ligand field theory (LFT) and Molecular orbital theory (MO). Ligand field theory, introduced in 1935 and built from molecular orbital theory, can handle a broader range of complexes and can explain complexes in which the interactions are covalent. The chemical applications of group theory can aid in the understanding of crystal or ligand field theory, by allowing simple, symmetry based solutions to the formal equations.

Chemists tend to employ the simplest model required to predict the properties of interest; for this reason, CFT has been a favorite for the discussions when possible. MO and LF theories are more complicated, but provide a more realistic perspective.

The electronic configuration of the complexes gives them some important properties:

Color of transition metal complexes
Transition metal complexes often have spectacular colors caused by electronic transitions by the absorption of light. For this reason they are often applied as pigments. Most transitions that are related to colored metal complexes are either d–d transitions or charge transfer bands. In a d–d transition, an electron in a d orbital on the metal is excited by a photon to another d orbital of higher energy, therefore d–d transitions occur only for partially-filled d-orbital complexes (d1–9). For complexes having d0 or d10 configuration, charge transfer is still possible even though d–d transitions are not. A charge transfer band entails promotion of an electron from a metal-based orbital into an empty ligand-based orbital (metal-to-ligand charge transfer or MLCT). The converse also occurs: excitation of an electron in a ligand-based orbital into an empty metal-based orbital (ligand-to-metal charge transfer or LMCT). These phenomena can be observed with the aid of electronic spectroscopy; also known as UV-Vis. For simple compounds with high symmetry, the d–d transitions can be assigned using Tanabe–Sugano diagrams. These assignments are gaining increased support with computational chemistry.

Colors of lanthanide complexes
Superficially lanthanide complexes are similar to those of the transition metals in that some are colored. However, for the common Ln3+ ions (Ln = lanthanide) the colors are all pale, and hardly influenced by the nature of the ligand. The colors are due to 4f electron transitions. As the 4f orbitals in lanthanides are "buried" in the xenon core and shielded from the ligand by the 5s and 5p orbitals they are therefore not influenced by the ligands to any great extent leading to a much smaller crystal field splitting than in the transition metals. The absorption spectra of an Ln3+ ion approximates to that of the free ion where the electronic states are described by spin-orbit coupling. This contrasts to the transition metals where the ground state is split by the crystal field. Absorptions for Ln3+ are weak as electric dipole transitions are parity forbidden (Laporte forbidden) but can gain intensity due to the effect of a low-symmetry ligand field or mixing with higher electronic states (e.g. d orbitals). f-f absorption bands are extremely sharp which contrasts with those observed for transition metals which generally have broad bands. This can lead to extremely unusual effects, such as significant color changes under different forms of lighting.

Magnetism
Metal complexes that have unpaired electrons are magnetic. Considering only monometallic complexes, unpaired electrons arise because the complex has an odd number of electrons or because electron pairing is destabilized. Thus, monomeric Ti(III) species have one "d-electron" and must be (para)magnetic, regardless of the geometry or the nature of the ligands. Ti(II), with two d-electrons, forms some complexes that have two unpaired electrons and others with none. This effect is illustrated by the compounds TiX2[(CH3)2PCH2CH2P(CH3)2]2: when X = Cl, the complex is paramagnetic (high-spin configuration), whereas when X = CH3, it is diamagnetic (low-spin configuration). Ligands provide an important means of adjusting the ground state properties.

In bi- and polymetallic complexes, in which the individual centres have an odd number of electrons or that are high-spin, the situation is more complicated. If there is interaction (either direct or through ligand) between the two (or more) metal centres, the electrons may couple (antiferromagnetic coupling, resulting in a diamagnetic compound), or they may enhance each other (ferromagnetic coupling). When there is no interaction, the two (or more) individual metal centers behave as if in two separate molecules.

Reactivity
Complexes show a variety of possible reactivities:

 * Electron transfers
 * Electron transfer (ET) between metal ions can occur via two distinct mechanisms, inner and outer sphere electron transfers. In an inner sphere reaction, a bridging ligand serves as a conduit for ET.
 * (Degenerate) ligand exchange
 * One important indicator of reactivity is the rate of degenerate exchange of ligands. For example, the rate of interchange of coordinate water in [M(H2O)6]n+ complexes varies over 20 orders of magnitude.  Complexes where the ligands are released and rebound rapidly are classified as labile.  Such labile complexes can be quite stable thermodynamically.  Typical labile metal complexes either have low-charge (Na+), electrons in d-orbitals that are antibonding with respect to the ligands (Zn2+), or lack covalency (Ln3+, where Ln is any lanthanide).  The lability of a metal complex also depends on the high-spin vs. low-spin configurations when such is possible.  Thus, high-spin Fe(II) and Co(III) form labile complexes, whereas low-spin analogues are inert.  Cr(III) can exist only in the low-spin state (quartet), which is inert because of its high formal oxidation state, absence of electrons in orbitals that are M–L antibonding, plus some "ligand field stabilization" associated with the d3 configuration.
 * Associative processes
 * Complexes that have unfilled or half-filled orbitals are often capable of reacting with substrates. Most substrates have a singlet ground-state; that is, they have lone electron pairs (e.g., water, amines, ethers), so these substrates need an empty orbital to be able to react with a metal centre.  Some substrates (e.g., molecular oxygen) have a triplet ground state, which results that metals with half-filled orbitals have a tendency to react with such substrates (it must be said that the dioxygen molecule also has lone pairs, so it is also capable to react as a 'normal' Lewis base).

If the ligands around the metal are carefully chosen, the metal can aid in (stoichiometric or catalytic) transformations of molecules or be used as a sensor.

Classification
Metal complexes, also known as coordination compounds, include virtually all metal compounds. The study of "coordination chemistry" is the study of "inorganic chemistry" of all alkali and alkaline earth metals, transition metals, lanthanides, actinides, and metalloids. Thus, coordination chemistry is the chemistry of the majority of the periodic table. Metals and metal ions exist, in the condensed phases at least, only surrounded by ligands.

The areas of coordination chemistry can be classified according to the nature of the ligands, in broad terms:
 * Classical (or "Werner Complexes"): Ligands in classical coordination chemistry bind to metals, almost exclusively, via their lone pairs of electrons residing on the main-group atoms of the ligand. Typical ligands are H2O, NH3, Cl−, CN−, en. Some of the simplest members of such complexes are described in metal aquo complexes, metal ammine complexes,
 * Examples: [Co(EDTA)]−, [Co(NH3)6]3+, [Fe(C2O4)3]3-

 * Organometallic chemistry: Ligands are organic (alkenes, alkynes, alkyls) as well as "organic-like" ligands such as phosphines, hydride, and CO.
 * Example: (C5H5)Fe(CO)2CH3

 * Bioinorganic chemistry: Ligands are those provided by nature, especially including the side chains of amino acids, and many cofactors such as porphyrins.
 * Example: hemoglobin contains heme, a porphyrin complex of iron
 * Example: chlorophyll contains a porphyrin complex of magnesium
 * Many natural ligands are "classical" especially including water.

 * Cluster chemistry: Ligands include all of the above as well as other metal ions or atoms as well.
 * Example Ru3(CO)12

 * In some cases there are combinations of different fields:
 * Example: [Fe4S4(Scysteinyl)4]2−, in which a cluster is embedded in a biologically active species.

Mineralogy, materials science, and solid state chemistry – as they apply to metal ions – are subsets of coordination chemistry in the sense that the metals are surrounded by ligands. In many cases these ligands are oxides or sulfides, but the metals are coordinated nonetheless, and the principles and guidelines discussed below apply. In hydrates, at least some of the ligands are water molecules. It is true that the focus of mineralogy, materials science, and solid state chemistry differs from the usual focus of coordination or inorganic chemistry. The former are concerned primarily with polymeric structures, properties arising from a collective effects of many highly interconnected metals. In contrast, coordination chemistry focuses on reactivity and properties of complexes containing individual metal atoms or small ensembles of metal atoms.

Nomenclature of coordination complexes
The basic procedure for naming a complex is:
 * 1) When naming a complex ion, the ligands are named before the metal ion.
 * 2) The ligands' names are given in alphabetical order. Numerical prefixes do not affect the order.
 * 3) * Multiple occurring monodentate ligands receive a prefix according to the number of occurrences: di-, tri-, tetra-, penta-, or hexa-.
 * 4) * Multiple occurring polydentate ligands (e.g., ethylenediamine, oxalate) receive bis-, tris-, tetrakis-, etc.
 * 5) * Anions end in o. This replaces the final 'e' when the anion ends with '-ide', '-ate' or '-ite', e.g. chloride becomes chlorido and sulfate becomes sulfato. Formerly, '-ide' was changed to '-o' (e.g. chloro and cyano), but this rule has been modified in the 2005 IUPAC recommendations and the correct forms for these ligands are now chlorido and cyanido.
 * 6) * Neutral ligands are given their usual name, with some exceptions: NH3 becomes ammine; H2O becomes aqua or aquo; CO becomes carbonyl; NO becomes nitrosyl.
 * 7) Write the name of the central atom/ion.  If the complex is an anion, the central atom's name will end in -ate, and its Latin name will be used if available (except for mercury).
 * 8) The oxidation state of the central atom is to be specified (when it is one of several possible, or zero), and should be written as a Roman numeral (or 0) enclosed in parentheses.
 * 9) Name of the cation should be preceded by the name of anion. (if applicable, as in last example)

Examples:

 * [Cd(CN)2(en)2] → dicyanidobis(ethylenediamine)cadmium(II)
 * [CoCl(NH3)5]SO4 → pentaamminechloridocobalt(III) sulfate
 * [Cu(H2O)6] 2+ → hexaaquacopper(II) ion
 * [CuCl5NH3]3− → amminepentachloridocuprate(II) ion
 * K4[Fe(CN)6] → potassium hexacyanidoferrate(II)
 * [NiCl4]2− → tetrachloridonickelate(II) ion (The use of chloro- was removed from IUPAC naming convention)

The coordination number of ligands attached to more than one metal (bridging ligands) is indicated by a subscript to the Greek symbol μ placed before the ligand name. Thus the dimer of aluminium trichloride is described by Al2Cl4(μ2-Cl)2.

Any anionic group can be electronically stabilized by any cation. An anionic complex can be stabilised by a hydrogen cation, becoming an acidic complex which can dissociate to release the cationic hydrogen. This kind of complex compound has a name with "ic" added after the central metal. For example, H2[Pt(CN)4] has the name tetracyanoplatinic (II) acid.

Stability constant
The affinity of metal ions for ligands is described by a stability constant, also called the formation constant, and is represented by the symbol Kf. It is the equilibrium constant for its assembly from the constituent metal and ligands, and can be calculated accordingly, as in the following example for a simple case:

 * xM (aq) + yL (aq) zZ (aq)

 * $$K_f = \frac{[\text{Z}]^z}{[\text{M}]^x[\text{L}]^y}$$

where : x, y, and z are the stoichiometric coefficients of each species. M stands for metal / metal ion, the L for Lewis bases , and finally Z for complex ions. Formation constants vary widely. Large values indicate that the metal has high affinity for the ligand, provided the system is at equilibrium.

Sometimes the stability constant will be in a different form known as the constant of destability. This constant is expressed as the inverse of the constant of formation and is denoted as Kd = 1/Kf. This constant represents the reverse reaction for the decomposition of a complex ion into its individual metal and ligand components. When comparing the values for Kd, the larger the value, the more unstable the complex ion is.

As a result of these complex ions forming in solutions they also can play a key role in solubility of other compounds. When a complex ion is formed it can alter the concentrations of its components in the solution. For example:

 * Ag$+ (aq)$ + 2NH3 Ag(NH3)$+ 2$

 * AgCl(s) + H2O(l) Ag$+ (aq)$ + Cl$− (aq)$

If these reactions both occurred in the same reaction vessel, the solubility of the silver chloride would be increased by the presence of NH4OH because formation of the Diammine argentum(I) complex consumes a significant portion of the free silver ions from the solution. By Le Chatelier's principle, this causes the equilibrium reaction for the dissolving of the silver chloride, which has silver ion as a product, to shift to the right.

This new solubility can be calculated given the values of Kf and Ksp for the original reactions. The solubility is found essentially by combining the two separate equilibria into one combined equilibrium reaction and this combined reaction is the one that determines the new solubility. So Kc, the new solubility constant, is denoted by:
 * $$K_c = K_{sp} K_f$$

<!--==Specific metal complexes==

Mercury
The speciation, solubility, mobility, and toxicity of mercury within aquatic environments are strongly influenced by its complexation with inorganic and organic ligands; most notable is mercury’s interaction with dissolved organic matter (DOM). As a result, the speciation of mercury depends on the concentration of each ligand and the stability constants of mercury complexes they form. For mercury, important inorganic ligands include hydroxide, chloride, and sulfide. However, complexation by natural organic compounds often controls the biogeochemical cycling of mercury. For example, complexation with DOM may limit the availability of Hg2+ for conversion to methylmercury or enhance the formation of elemental mercury (Hg0) from Hg2+, further lowering the availability of Hg2+ for conversion to methylmercury.

Mercury binding to dissolved organic matter is evaluated in terms of the stability constants of Hg-DOM complexes. The complexation reaction between Hg2+ and an organic ligand is assumed to take the following form:

Hg2+ + Ln− → 2 HgL(2-n)+

where K, the stability constant, is equal to:

K= [HgL(2-n)]/[Hg2+][Ln−].

Metal cations bind to the acid sites in organic matter, the most common of which include carboxylic acids, phenols, amines, alcohols, and thiols. Mercury is classified as a type B metal and shows a preference for ligands of sulfur, the less electronegative halides, and nitrogen, over ligands containing oxygen. Therefore, mercury is expected to preferentially bind with thiol and other sulfur-containing functional groups which, despite their relatively low abundance in DOM, far exceed the amount of mercury available in aquatic environments. Previous research has shown that binding of Hg2+ by organic ligands does not occur immediately when both are present; instead, complexation tends to follow a pseudo-first-order rate constant with exponential decay. Predicting mercury speciation due to Hg-DOM complexes is difficult due to organic matter heterogeneity, electrostatic effects, and the variation in stability constants; however, recent studies have shown conditional stability constants for mercury binding to be in the range of 1022 – 1028. Competitive ligand exchange (CLE) experiments, in which Hg binding to natural organic ligands is measured in the presence of an added ligand whose complexation with Hg2+ is well characterized, is used to determine the concentrations and apparent stability constants of natural mercury complexes. One such experiment used both chloride and thiosalicyclic acid (TSA) as competing ligands; estimated conditional stability constants ranged from 1026.1 to 1026.9 for chloride competition and 1027.3 to 1029.2 for TSA competition. This study showed that lower concentrations of binding sites with higher stability constants are more important for Hg speciation than higher concentrations of weaker binding sites.

Conditional stability constants vary with pH due to competition with protons for binding sites. They also vary with salinity and, contrary to what may be expected, are generally lower in freshwater than seawater. In seawater, organic complexes must have very high K values in order to compete with chloride for mercury complexation. In freshwater systems, hydroxide is the most common inorganic ligand, yet its concentration is low enough that organic ligands do not need to have a high K value to compete for mercury complexation. In both environments, organic compounds dominate mercury complexation.

In examining the role of DOM in mercury speciation under sulfidic environments, we see that inorganic sulfide also plays an important role within anoxic environments due to the very strong binding of sulfide with mercury. HgS$0 (aq)$, Hg(S2H)−, Hg(SH)$0 2$, and HgS(s) are likely to be the most important species. Recent studies however, have shown that stability constants of Hg-DOM complexation are higher than those for mercury sulfide complexation. These results then imply that organic matter can out complete sulfide for the complexation of mercury within anoxic environments.

DOM has been shown to affect the bioaccumulation of mercury via photochemical reduction and methylation. Reduction of Hg2+ to Hg0 by sunlight is a commonly occurring process, yet is enhanced in the presence of DOM. Conversely, photolysis of dissolved organic carbon (DOC) can produce radical oxygen species including hydroxyl radicals (−OH), which in turn have been shown to oxidize Hg0 to Hg2+. Conversion of ionic mercury (especially Hg2+) to methyl mercury is an important process, as methyl mercury is a neurotoxin and has been show to bioaccumulate within the food chain. Mercury methylation is a microbially mediated process wherein bacteria assimilate neutrally charged mercury species through passive diffusion. Complexation with DOC limits this uptake mechanism as the DOC molecules are too large to pass through cell membranes; however, at low pH, DOC is less negatively charged and therefore less likely to complex mercury, thereby making mercury more available for methylation. Additionally, DOM-mediated reduction of Hg2+ to Hg0 would further limit the availability of mercury for methylation by leading to the mercury volatilization. Direct methylation of mercury can also occur by reaction with humic and fulvic acids in DOM. -->

Application of coordination compounds
As metals only exist in solution as coordination complexes, it follows then that this class of compounds is useful in a wide variety of ways.

Bioinorganic chemistry
In bioinorganic chemistry and bioorganometallic chemistry, coordination complexes serve either structural or catalytic functions. An estimated 30% of proteins contain metal ions. Examples include the intensely colored vitamin B12, the heme group in hemoglobin, the cytochromes, the chlorin group in chlorophyll, and carboxypeptidase, a hydrolytic enzyme important in digestion. Another complex ion enzyme is catalase, which decomposes the cell's waste hydrogen peroxide. Synthetic coordination compounds are also used to bind to proteins and especially nucleic acids (e.g. anticancer drug cisplatin).

Industry
Homogeneous catalysis is a major application of coordination compounds for the production of organic substances. Processes include hydrogenation, hydroformylation, oxidation. In one example, a combination of titanium trichloride and triethylaluminium gives rise to Ziegler–Natta catalysts, used for the polymerization of ethylene and propylene to give polymers of great commercial importance as fibers, films, and plastics.

Nickel, cobalt, and copper can be extracted using hydrometallurgical processes involving complex ions. They are extracted from their ores as ammine complexes. Metals can also be separated using the selective precipitation and solubility of complex ions. Cyanide is used chiefly for extraction of gold and silver from their ores.

Phthalocyanine complexes are an important class of pigments.

Analysis
At one time, coordination compounds were used to identify the presence of metals in a sample. Qualitative inorganic analysis has largely been superseded by instrumental methods of analysis such as atomic absorption spectroscopy (AAS), inductively coupled plasma atomic emission spectroscopy (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS).

title: Coordination complex