Crystal and Molecular Structure of [2,3-Bis(dimethylarsino)-1,1,1,4,4,4,-hexafluorobut-2-ene-As, As]tricarbonyldiiodotungsten(II)

Abstract

Crystals of the title compound, Me2AsC(CF3):C(CF3)AsMe2WI2(CO)3, are monoclinic, a = 15.37(2), b = 9.529(1), c = 15.967(3) Å, β = 112.03(2)°, Z = 4, space group P21/c. The structure was determined by Patterson and Fourier syntheses and refined by full-matrix least-squares procedures to a final R of 0.069 for 1823 observed (of a total of 2778) reflexions. The tungsten atom is seven-coordinate with a distorted capped octahedral environment, the capping group being a carbonyl (W—C, 1.94(3) Å). The capped face consists of the two remaining carbonyl groups (W—C, 1.97(4) and 2.00(4) Å) and one of the arsenic atoms from the bidentate ligand (W—As, 2.556(3) Å). The uncapped face contains the two iodine atoms (W—I, 2.848(2) and 2.856(2) Å) and the remaining arsenic atom (W—As, 2.618(3) Å), this bond length (trans to CO), being significantly longer (by 0.062 Å) than the other (trans to I) W—As distance.