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.