A Valence Bond Description of Dizwitterionic Dithiolene Character in an Oxomolybdenum–Bis(dithione) Complex

A Valence Bond Description of Dizwitterionic Dithiolene Character in an Oxomolybdenum–Bis(dithione) Complex:

Abstract

Metallodithiolene non-innocence is explored in an oxomolybdenum–bis(dithione) complex, [Mo⁴⁺O(iPr₂Pipdt)₂Cl][PF₆] (where Pipdt is N,N′-piperazine-2,3-dithione), which has a piperazine ring as an integral part of the dithiolene ligand. The title complex displays spectroscopic features that are unusual for a formally reduced Mo^IV–dithiolene complex, namely a low-energy metal-to-ligand charge-transfer band with appreciable intensity and C–C and C–S stretching frequencies that are markedly different from those of oxomolybdenum complexes coordinated to dianionic dithiolene ligands. The electronic structure of the ligand has been described in valence bond terms as a resonance hybrid of dithione and dizwitterionic dithiolene structures.

Metallodithiolene non-innocence is explored in [Mo⁴⁺O(iPr₂Pipdt)₂Cl][PF₆] (Pipdt: N,N′-piperazine-2,3-dithione), which possesses a piperazine ring as an integral part of the dithiolene ligand and displays unusual spectroscopic features for a formally reduced Mo^IV–dithiolene complex. The electronic structure of the ligand can be described in valence bond terms as a resonance hybrid of dithione and dizwitterionic dithiolene.