Crystal structure of tetraethylammonium bis(tetracarbonylmolybdenum)-tetrathiotungstate, [Et4N](2)[(OC)(4)MoS2WS2Mo(CO)(4)] and synthesis, infrared spectra, Mo-95 NMR spectra and cyclic voltammetry of new linear trinuclear Mo(W)-S carbonyl clusters containing mixed-valence metal atoms [(OC)(4)MS2M ' SM(CO)(4)](2-) (M, M ' = Mo or W)

Four trinuclear molybdenum(tungsten)-sulfur carbonyl cluster compounds, [Et 4N](2)[(OC)(4)MoS2MoS2Mo(CO)(4)] (1), [Et4N](2)[(OC)(4)WS2WS2W(CO)(4)] (2), [Et4N](2)[(OC)(4)MoS2WS2Mo(CO)(4)] (3), [Et4N](2)[(OC)(4)WS2MoS2W(CO)(4)] (4) have been prepared by both reaction of [M(CO)(4)(S2CNEt2)](-) with M'S- 4(2-) in MeOH and reaction of MeCN solution of M(CO)(6) with M'S-4(2-) in M eOH (M = Mo, W: M' = Mo, W). These complexes has been characterized by rout ine elemental analysis and spectroscopy and the structures of 1 and 3 have been determined by X-ray crystallography. The structure study reveals that the anion of 3 contains a heteronuclear MoW-S trimetallic core, [MoS2WS2Mo] (2-), consisting of two perpendicular rhombic MoS2W units sharing a tungste n atom. The Mo-W bond distances are 3.028(2) and 3.031(2) Angstrom and the Mo-W-Mo angle is 176.04(5)degrees. The average bond lengths of W-S and Mo-S are 2.21 and 2.54 Angstrom, respectively. The X-ray. structure, IR, CV (cy clic voltammetry) and Mo-95 NMR studies on these four cluster complexes ind icated that these cluster complexes possess wide separated oxidation states of metal atoms and exhibit the charge transfer, M-L-->(MS4)-S-H (M-L repre sents a low-valance metal atom and M-H a high valence metal atom), between the two different valence metallic centers in the cluster complexes. It has been found that the charge transfer, M-L --> (MS4)-S-H, in the complexes a re: 1>4, 3>2, 1>3, 4>2, 1>2 and 3 similar to 4 implying the electron-donati on ability of low-valence metal atoms in the complexes is Mo-o > W-o and th e electron-accepted ability of the high valence metal atoms in the complexe s is Mo-VI > W-VI. (C)1998 Elsevier Science Ltd. All rights reserved.