Six- and seven-co-ordinate complexes of molybdenum(II) and tungsten(II) with thioether ligands. Crystal structures of [WI2(CO)3{4-MeC6H4S(CH2)2SC6H4Me-4}] and [WI2(CO)2{MeS(CH2)2S(CH2)2SMe-S,S′,S″}

Abstract

Reaction of [MI2(CO)3(NCMe)2](M = Mo or W) with a slight excess of RS(CH2)2SR (R = Ph, 4-MeC6H4 or 4-FC6H4) in CH2Cl2 at room temperature gave [MI2(CO)3{RS(CH2)2SR}]. The molecular structure of [WI2(CO)3{4-MeC6H4S(CH2)2SC6H4Me-4}] has been determined by X-ray crystallography. It shows that the tungsten has essentially capped-octahedral geometry with a carbonyl ligand in the unique capping position. Low-temperature 13C NMR studies on the tungsten complexes suggest that their structures in solution are similar to the solid-state structure found. Reaction of [WI2(CO)3(NCMe)2] with 2 equivalents of PhS(CH2)2SPh in CH2Cl2 afforded [WI(CO)3{PhS(CH2)2SPh-S}{PhS(CH2)2SPh-S,S′}]I which was reduced by LiBun to cis-[W(CO)2{PhS(CH2)2SPh-S.S′}2]. Equimolar quantities of [MI2(CO)3(NCMe)2](M = Mo or W) and MeS(CH2)2S(CH2)2SMe reacted in CH2Cl2 to give [MoI2(CO)2{MeS(CH2)2S(CH2)2SMe-S,S″,S″}] and [WI2(CO)3{MeS(CH2)2S(CH2)2SMe-S,S″}]. The latter was converted in CHCl3 into [WI2(CO)2{MeS(CH2)2S(CH2)2SMe-S,S″,S″}], the molecular structure of which is essentially a capped octahedron with a carbonyl ligand in the unique capping position.