Electronic structures of trithiapentalene analogues

Abstract

The electronic structures of trithiapentalene analogues are studied by ab initio molecular orbital methods and density functional theory. Calculation of the normal vibration frequencies for substituted trithiapentalenes with C2v symmetry indicates that σ-substituted trithiapentalene structures with C2v symmetry are more destabilized than by substitution with the π-type group. CiLC-IRC analysis of the electronic structures for trithiapentalene analogues is performed for the pathway between the C2v and Cs structures for 1,6,6aλ4-trithiapentalene and 1,6-dithia-6aλ4-oxapentalene, and it is found that the diradical states in both compounds are a critical factor in determining the stability of the structures with C2v symmetry. Furthermore, the electronic state of 1,6,6aλ4-trithiapentalene with C2v symmetry has less diradical character than that of 1,6-dithia-6a-oxapentalene.