United atom models for polyatomic ligands. Part III. Hydrogen and methyl derivatives and the pseudohalides

Abstract

The United Atom model is applied to simple hydrogen and methyl substituted anions of Group V and VI and to some pseudohalide ions. The electronic structures deduced using the criteria of Part 1 generally in the absence of experimental data show that in most cases the highest occupied orbital has π-like symmetry and is localized on the substituents. The ligands is capable of side-on σ donation with such an orbital alone or end-on π bond donation in conjunction with the next highest lying σ donor orbital. The bridging ability of these ligands requires the use of the σ orbital and one π lobe and is highly dependent on the bonding nature of the π orbital and the symmetry of the ligand. Lewis π acidity is unimportant in the simple anions but can occur in the pseudohalides.