Which of the following types of square planer complexes has maximum number of geometric isomer ?
where Mn is central metal, A, B, C and D are different monodentate ligands, and AB is an unsymmetrical bidentate ligand.

Options

A. `MA_(2)B_(2)`
B. `MA_(2)BC`
C. MABCD
D. `M(AB)_(2)`

Answer

C

Explanation

Geometric isomerism arises in heteroleptic complexes due to different possible geometric arrangements of the ligands. Square planer complex of the type MABCD exits as three isomers. Their space arrangements are obtained by fixing the position of one ligand such as A and placing any one of the remaining three ligands one by one at the opposite end on the same axis:

Two of these are cis and one is trans. Each of the other type of square planer complex has just two geometric isomers: one cis and one trans-