Structural studies of binuclear suiphido-bridged complexes of tungsten. Preparation and X-ray crystal structures of [S2W(µ-S)2W(NNMe2)2(PPh3)] and [{W(SBut)2(PMe2Ph)}2(µ-S)2]·CH2Cl2

Abstract

The reaction of [NBuⁿ ₄]₂[WS₄] with [WCl(NNMe₂)₂(PPh₃)₂]Cl yields the asymmetric binuclear complex [S₂W(µ-S)₂W(NNMe₂)₂(PPh₃)](1). Complex (1) crystallizes in space group Cc, with a= 15.389(2), b= 10.292(4), c= 18.406(2)Å, β= 90.43(1)°, and Z= 4; final R= 0.061 based on 4 091 reflections collected, 2 116 used. One tungsten is trigonally pyramidally co-ordinated with two NNMe₂ groups in the equatorial plane and one axial and one equatorial bridging sulphide with a W–W separation of 3.024(1)Å. The reaction of cis-[W(N₂)₂(PMe₂Ph)₄] with Bu^tSH gives the symmetric binuclear complex [{W(SBu^t)₂(PMe₂Ph)}₂(µ-S)₂](2). Complex (2) crystallises in space group P, with a= 9.654(4), b= 10.331(4), c= 13.288(5)Å, α= 78.09(1), β= 69.36(1), γ= 82.49(1)°, and Z= 1; final R= 0.071 based on 4 732 reflections collected, 2 310 used. The centre of symmetry imposes planarity on the W₂S₂ system with a W–W distance of 2.736(2)Å. Each tungsten has distorted trigonal-bipyramidal geometry with bridging sulphide and phosphorus in the apical sites.