Crystal and molecular structure of W(eta/sup 2/-HC double bond COAlCl/sub 3/)(CO)(PMe/sub 3/)/sub 3/Cl, a product of the coupling of methylidyne and carbonyl ligands on tungsten

A single-crystal x-ray diffraction analysis has been performed on the title complex, which was prepared by Holmes and Schrock through AlCl/sub 3/-promoted coupling of W(CH)(PMe/sub 3/)/sub 4/Cl with carbon monoxide. The complex crystallizes in the centrosymmetric monoclinic space group P2/sub 1//c with a = 10.420 (2) A, b = 12.896 (2) A, c = 19.319 (4) A, ..beta.. = 105.880 (15)/sup 0/, V = 2497.1 (9) A/sup 3/, rho(calcd) = 1.73 g cm/sup -3/ for Z = 4, and mol wt = 650.0. Automated four-circle diffractometer intensity data (Syntex P2/sub 1/) were used to solve the structure; refinement led to R/sub F/ = 3.2% and R/sub wF/ = 3.0% for all 4423 unique reflections with 4.0/sup 0/ < 2 theta < 50.0/sup 0/ (Mo K..cap alpha.. radiation). The octahedral coordination environment about the central tungsten atom consists of three meridional PMe/sub 3/ ligands, a terminal carbonyl, a chloride, and an eta/sup 2/-HC double bond COAlCl/sub 3/ ligand. The last is oriented parallel to the carbonyl ligand and is best described as a substituted acetylene with an acetylenic carbon-carbon linkage of 1.316 (6) A and short tungsten-carbon distances of 2.034 (4) and 2.009 (5) A. The aluminum-oxygen distance is 1.751 (3)more » A; this value represents a significantly stronger Al-O interaction than has been observed in other structures containing Al-O (carbonyl; acyl) linkages.« less