SYNTHESIS AND STRUCTURE OF W2CL4(MU-DPPM)(2)(ETA(2)-MU-CH3CN)

A new ditungsten compound with a bridging ligand in a novel geometry, W2Cl4(mu-dppm)(2)(eta(2)-mu-CH3CN) where dppm is bis(diphenylphosphino )methane, has been prepared from a quadruply bonded starting material. The structure of this compound is an example of a dinuclear tungsten compound with an eta(2)-mu-bonded acetonitrile. The use of acetonitril e as a solvent during the preparation of the known compound W2Cl4(mu-d ppm), results in the incorporation of an acetonitrile molecule in a br idging position with the C-N of this ligand perpendicular to the W-W a xis. The bridging acetonitrile is no longer linear. The angle formed b y the three-atom chain of acetonitrile, C-C-N, is 116.3(7)degrees with a C-N bond distance of 1.303(8) Angstrom. The W-W bond distance is 2. 4981(10) Angstrom, significantly longer than the distance of 2.269(1) Angstrom observed in the parent compound W2Cl4(mu-dppm). Crystallograp hic data for this compound is as follows: P2(1)/c with a=12.577(5), b= 18.644(8), c=27.024(8) Angstrom, beta=95.98(2)degrees, V=6302(4) Angst rom(3) and Z=4.