On the charge distribution in complexes

Abstract

Dipole moment, X-ray photoelectron (X-p.e.) spectroscopic, and electrochemical measurements are evaluated as means of determining charge distribution in complexes. The first is of limited value because of the inability to determine individual bond moments. X-P.e. spectroscopy is of most general application but limited by lack of sensitivity. Redox measurements can only be interpreted clearly where there are no π-bonding ligands. The data are consistent with tertiary phosphines and chloride ions being good electron donors, chlorine and nitrogen atoms being strongly electron withdrawing, and the so-called electron-donor ligands N₂, CO, and NO (even formal NO⁺) being, in fact, electron withdrawing. On the other hand the formally anionic hydride ligand is very strongly electron donating, being only slightly negative in its complexes.