Chemistry - Coordination Chemistry Question with Solution | TestHub

Coordination Isomerism: All given options are binuclear complexes (anionic and cationic parts) that can exchange ligands; thus, all satisfy this condition.

Magnetic Property: We must find the complex where both metal centers have no unpaired electrons ($n=0$).

(A) Cr³⁺ ($d^3$) and (B) Ni²⁺ ($d^8$ in tetrahedral/octahedral) are paramagnetic.

(D) Cu²⁺ ($d^9$) is paramagnetic.

(C) $[Pt(N{H}_3{)}_4][PtC{l}_4]$ contains Pt²⁺ ($d^8$). Since Pt is a $5d$ metal, it always forms square planar complexes with a large crystal field splitting, pairing all electrons.

Therefore, Option C is the only fully diamagnetic complex.