Chemistry / Chem 2390 · Procedure · 60–90 seconds
Naming a Coordination Compound
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Naming a coordination compound means naming the ligands alphabetically with multiplying prefixes, following them with the metal's name and a Roman numeral oxidation state determined by balancing the ligand charges against the coordination sphere's overall charge, and adding the suffix -ate to the metal name if the complex is an anion.
In [Cr(H2O)4Cl2]Cl, the coordination sphere carries a 1+ charge to balance the outer chloride; with four neutral water ligands and two 1− chloride ligands inside the brackets, +1 = −2 + x gives chromium an oxidation state of 3+, so the full name is tetraaquadichlorochromium(III) chloride.
Forgetting that ligands outside the coordination sphere's brackets do not count toward the oxidation-state balance, and including them anyway, gives an oxidation state that does not match the complex's actual charge.