Electronic Structure of Monodithiolated IronOxotungsten Heterometallic Complexes: Integer-Spin FeW Assembly

Abstract

Fe-W heterometallic complexes, in which an FeX2 (X = Cl, SPh) moiety is attached to monodithiolene oxotungsten through a sulfide bridge, that is, [Ph4P]2[Cl2Fe(S)2WOS2] (1), [Ph4P]2[Cl2Fe(S)2WOS2(DMED)] (2, DMED = dimethylethylenedicarboxylate), [Ph4P]2[Cl2Fe(S)2WO(tdt)] (3, tdt = toluenedithiolate), [Ph4P]2[(SPh)2Fe(S)2WO(tdt)] (4), and [Ph4P]2[Cl2Fe(S)2WO(edt)] (5, edt = ethanedithiolate), are reported. Mössbauer and EPR spectroscopy, magnetism, electrochemistry, and electronic structural analysis based on DFT and TD-DFT calculations show the transfer of electron from the iron center to the tungsten center, thus resulting in a ferromagnetically coupled Fe(III) W(V) unit, along with antiferromagnetic intermolecular interactions, from the starting Fe(II) and W(VI) compounds. A net spin of a S = 3 ground state, which arises from ferromagnetically coupled Fe(III) and W(V) atoms, displays a rare X-band EPR in normal mode at g ≈ 7 in the solid state.