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^IIIW^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.