Electronic Structure of Lone Pairs. III. H2S2, H2O2, N2H4, and Diimides

The electronic structure, the electronic transition, and the interaction of lone pairs of H2S2, H2O2, and N2H4 for several dihedral angles are studied by the semi-empirical ASMO SCF method, and their dependencies on the dihedral angle is discussed. Also, the interaction of the lone pairs of diimides, N2H2, N2F2, and (CH3)2N2, the relative stability of the cis forms and of their trans form, and the electronic transition energies of these molecules are calculated. The stable forms of N2H2 and (CH3)2N2 are calculated to be of the trans form, but that of N2H2 is the cis form. An energy component analysis of these compounds has been made. The main factor in the lack of stability of the cis form of N2H2 is shown to be the core-core repulsion term, Vnn. On the other hand, in H2S2 and N2H4 not only the Vnn term but also the electrostatic interaction term, ,jΣ(2Jij−Kji), contributes to their instability.