Crystal structures of Ph3AsCl2 and beta-Ph3AsBr2

Colourless single crystals of Ph3AsCl2, as well as of beta-Ph3AsBr2 were ob tained from acetonitrile solutions and were suitable for X-ray structure de terminations. Ph3AsCl2: Space group P2(1)2(1)2(1), Z = 4, lattice dimensions at -90 degre es C: a = 1247.9(2), b 1267.5(1), c = 1033.4(1) pm, R-1 = 0.0484. beta-Ph3A sBr2: Space group P1, Z = 4, lattice dimensions at -80 degrees C: a = 949.1 (1), b = 1159.7(1), c = 1693.7(2) pm, alpha = 98.32(1)degrees, beta = 103.6 4(1)degrees, gamma = 109.44(1)degrees R1 = 0.0628. The structures consist o f Ph3AsX2 molecules (X = Cl, Br) with trigonal-bipyramidal coordination of the arsenic atom with the halogen atoms in the axial positions.