Q.Classify the complexes as cationic, anionic or neutral. Na₄[Fe(CN)₆], Co(NH₃)₆Cl₂, Cr(H₂O)₂(C₂O₄)₂ ³⊖, PtCl₂(en)₂ and Cr(CO)₆.

Coordination complexes are classified along two entirely independent axes. The first axis is by the TYPES of ligands present: a homoleptic complex has its metal ion bound to only ONE type of ligand throughout (e.g. [Co(NH3)6]3+, every ligand is NH3), while a heteroleptic complex has its metal ion surrounded by MORE THAN ONE type of ligand (e.g. [Co(NH3)4Cl2]+, which carries both NH3 and Cl- ligands together). The second axis is by the SIGN OF THE NET CHARGE carried specifically by the coordination sphere itself, considered alone inside its square brackets: a cationic complex has a positively charged coordination sphere (e.g. [Zn(NH3)4]2+, or the [Co(NH3)5Cl]2+ sphere inside [Co(NH3)5Cl]SO4); an anionic complex has a negatively charged coordination sphere (e.g. [Ni(CN)4]2-, or the [Fe(CN)6]3- sphere inside K3[Fe(CN)6]); and a neutral complex has neither -- its coordination sphere already carries zero net charge and therefore …