Synthesis of chloro(trimethylphosphine)tris(trimethylsilylmethyl)tungsten(IV); synthesis and molecular structure of di-µ-chloro-bis[dicarbonyl(trimethylphosphine)(1—2-η-trimethylsilylmethylcarbonyl)tungsten(II)]

Abstract

The interaction of [MgCl(CH₂SiMe₃)] or [Mg(CH₂SiMe₃)₂] with [WCl₄(PMe₃)₂] yields the five-co-ordinate paramagnetic tungsten(IV) alkyl [WCl(CH₂SiMe₃)₃(PMe₃)] which reacts with carbon monoxide to give an η²-acyl dimeric complex [{WCl(1—2-η-COCH₂SiMe₃)(CO)₂(PMe₃)}₂]. The crystal structure of the latter has been determined from three-dimensional X-ray diffraction data collected by counter methods. It crystallizes in the monoclinic space group P2₁/c, isomorphous with the molybdenum analogue, with a= 8.420(3), b= 10.449(3), c= 19.300(4)Å, β= 90.59(2)°, and Z= 2. The final R value was 0.016 for 1 218 independent observed reflections. The molecule exists as a chloride-bridged dimer with an η²-acyl linkage. The tungsten–carbon(acyl) bond length is 2.029(7)Å and the tungsten–oxygen(acyl) distance is 2.289(5)Å.