For our complex ion, Co(en)2Cl2+, the coordination number is also six. 2 electron pairs are donated to the Co3+ion by each chloride ion, Cl-, ligand. The remaining 4 electron pairs are donated by the two Ethylenediamine ligands, the Ethylenediamine ligand being bidentate;forming two bonds to the metal per “en”.
Because each “en” ligand in our Complex
is bidentate,two different Isomers of our Complex are possible; a cis form and a trans form. These are pictured below