Synthesis, properties and structural features of molybdenum(V) oxide trichloride complexes with neutral chalcogenoether ligands.

Complexes of oxotrichloromolybdenum(v) with neutral group 16 donor ligands, [MoOCl3(L-L)] (L-L = RS(CH2)2SR, R = iPr, Ph; MeS(CH2)3SMe; MeSe(CH2)2SeMe; MeSe(CH2)3SeMe), [{MoOCl2(EMe2)}2(μ-Cl)2] (E = S, Se, Te), [(MoOCl3)2{o-C6H4(EMe)2}]n (E = Se or Te) and [(MoOCl3)2{MeTe(CH2)3TeMe}]n, have been obtained by reaction of the ligands with [MoOCl3(thf)2] or MoOCl3 in either CH2Cl2 or toluene, and characterised by microanalysis, IR and UV-visible spectroscopy and magnetic measurements. The telluroethers are the first examples containing Mo in a positive oxidation state. X-ray crystal structures are reported for the six-coordinate fac-[MoOCl3{MeS(CH2)3SMe}], mer-[MoOCl3{iPrS(CH2)2SiPr}] and mer-[MoOCl3{MeSe(CH2)2SeMe}], as well as the six-coordinate chloride-bridged dimers, [{MoOCl2(SMe2)}2(μ-Cl)2] and [{MoOCl2(SeMe2)}2(μ-Cl)2]. The structure of the mixed-valence decomposition product, [MoIVCl{o-C6H4(TeMe)2}2(μ-O)MoVOCl4], was also determined. In toluene solution MoOCl4 is reduced by MeS(CH2)3SMe to produce the Mo(v) complex, [MoOCl3{ MeS(CH2)3SMe}]. Crystal structures of the previously unknown diphosphine analogue, [MoOCl3{Me2P(CH2)2PMe2}], and the mixed-valence derivative [MoIVCl{Me2P(CH2)2PMe2}2(μ-O)MoVOCl4] are also reported for comparison and help to clarify earlier contradictory literature reports. In contrast to the dimeric EMe2 complexes, [{MoOCl2(EMe2)}2(μ-Cl)2], PMe3 forms the monomeric complex, fac-[MoOCl3(PMe3)2].