Chemistry - Coordination Chemistry Question with Solution | TestHub

The question asks to identify heteroleptic complexes that exhibit d$\pi$-$\pi$* interaction. This interaction involves the donation of electron density from a filled d-orbital of the metal to an empty $\pi$* antibonding orbital of the ligand. This is a type of back-bonding.

Let's analyze the options:

A. Sodium nitroprusside: Na₂[Fe(CN)₅NO]. The NO ligand is a strong $\pi$-acceptor, having empty $\pi$* orbitals that can accept electron density from the metal's d-orbitals, thus showing d$\pi$-$\pi$* interaction. It is heteroleptic as it has two different types of ligands (CN⁻ and NO).

B. Potassium ferricyanide: K₃[Fe(CN)₆]. The CN⁻ ligand is a $\pi$-acceptor, but the complex is homoleptic (all ligands are CN⁻). The question specifically asks for heteroleptic complexes.

C. Zeise's salt: K[PtCl₃(C₂H₄)]. The ethene (C₂H₄) ligand has empty $\pi$* orbitals that can accept electron density from the Pt d-orbitals, forming a d$\pi$-$\pi$* interaction (synergic bonding). It is heteroleptic as it has two different types of ligands (Cl⁻ and C₂H₄).

D. Wilkinson's catalyst: [RhCl(PPh₃)₃]. The PPh₃ (triphenylphosphine) ligand is a $\pi$-acceptor due to its empty d-orbitals (d$\pi$-d$\pi$ interaction), not $\pi$* orbitals. While it is heteroleptic, the interaction type is different.

Therefore, Sodium nitroprusside and Zeise's salt show d$\pi$-$\pi$* interaction and are heteroleptic.

The final answer is $\boxed{A,C}$