Question

The corresponding CoH(PF₃)₄ complex is observed to be readily deprotonated whereas the triphenylphosphite complex (CoH{P(OPh)₃}₄) is not. Explain this reactivity difference.

Answer 1

The deprotanation capability of a metal complex is mainly depends on the stability of charged metal complex formed after deprotanation.

In the first complex the ligand PF3 is a good pi accepting ligand. This pi accepting ability is mainly attributed to high electronegative flourine atoms which makes the ligand better electron pulling ability. So after deprotanation, the negative charge on the complex is stabilized by these PF3 ligands.

But in the second complex the negative charge is not stabilized by P(OPh)3 ligands, which are not a good pi accepting ligands. So the negative charged complex is not very stable as like first complex.