Some Considerations About Bond Indices in Non-orthogonal Bases and the MO Calculation of Valence and Oxidation Number

In order to guarantee the desired invariance properties of bond indices, we show the importance of expliciting the tensor character of the matrices concerned, so as to deal with a contraction in the tensor sense between a covariant index and a contravariant one. A straightforward definition of oxidation numbers is proposed. IEH calculations of valence and oxidation numbers for some appropriate examples are performed: they emphasize the role of "secondary" bonds in N and C-containing compounds; the hydrogen behaviour in half-bonds and strong H-bonds is satisfactorily accounted for; valence and oxidation number values are assigned to Fe, Co and Ni in a few complexes.