Redox-controlled interconversion between trigonal prismatic and octahedral geometries in a monodithiolene tetracarbonyl complex of tungsten

The monodithiolene compound [W(S2C2Me2)(CO)4], 1, is an unusual example of a trigonal prismatic compound with multiple π-acid ligands. This geometry arises in part from a HOMO−LUMO configuration interaction (both b1), which is lost if the geometry is changed to octahedral. One-electron reduction of 1, which induces a change to octahedral geometry, involves two-electron reduction of tungsten and one-electron oxidation of dithiolene ligand. The properties of 1 (W(ll), d4) are contrasted with those of [W(Me2pipdt)(CO)4], (W(0), d6)