Question

the pi-complexes are known for the transition metals only.explain.

Answer 1

because no other elements other than transition elements have vacant d orbitals

Answer 2

Hey !!

Transition metals have vacant d-orbitals in their atoms or ions into which the electron pairs can be donated by ligands containing π - electrons.

Example :- C₆H₆ , CH₂ = CH₂ etc.

This dπ - pπ bonding is possible.

Good luck !!