Crystal structures of o-phenylenediarsine oxychloride (a redetermination) and o-phenylenediarsine oxybromide

Abstract

The crystal structures of the title compounds have been established by X-ray diffraction at 295 K, being refined by full-matrix least-squares to residuals of 0.054 (0.051) respectively 2715 (469) reflections with I > σ(I)]. Crystals are monoclinic, space group C2/c, the compounds being isomorphous. Oxychloride: a = 14.534(4), b = 8.337(2), c = 7.653(1)Ǻ, β = 106.48(1)°. Oxybromide: a = 14.884(4), b = 8.360(2), c = 7.726(1)Ǻ, β = 105.30(1)°, Z = 4. With the exception-of the arsenic- halogen distance, the geometries of the two molecules are identical within the limits of error: for the oxychloride As-O-As, 121.8(3); Cl- As-O,98.03(6); Cl-As-C, 97.2(2); O-As-C, 92. 9(2)° ; As-O, 1.787(3); As-C, 1.941(5) Ǻ. As-Cl is 2.222(2) and As-Br 2.381(2) Ǻ.