Question

Synergic effect in coordination compounds

Answer 1

π backbonding, also called π backdonation, is a concept from chemistry in which electrons move from an atomic orbital on one atom to an appropriate symmetry antibonding orbital on a π-acceptor ligand. ... Electrons from the metal are used to bond to the ligand, in the process relieving the metal of excess negative charge.

Answer 2

$\pi \: \: is \: \: \: backdonation$