CRYSTAL AND MOLECULAR STRUCTURE OF HEXAKIS(THIOUREA)NICKEL(2) BROMIDE

The crystal structure of hexakis(thiourea)nickel(II) bromide, Ni[SC(NH2)M2]6Br2, has been determined by three-dimensional X-ray diffraction techniques from 1219 reflections measured at ambient temperature with an automatic diffractometer. The compound crystallizes in the monoclinic space group I2/c with a = 16.703 ± 0.005 Å, b = 8.979 ± 0.002 Å, c = 16.909 ± 0.002 Å, β = 92.8 ± 0.1°, = 1.80 g/cm3, and Dc = 1.78 g/cm8 for four molecules per unit cell. The structure, including hydrogen atoms, was refined by least-squares methods to aconventional R of 0.053. The structure consists of Ni[SC(NH2)2]6 molecular ions and Br- ions. The nickel atom is located on a centerof symmetry and is coordinated to sixsulfur atoms in a distorted octahedral (D3d, trigonal antiprism, if the NH2 groups are disregarded) local environment. The orientation of the thiourea groups relative to the nickel atom is such that each sulfur atom uses an sp2 orbital to form the metal-sulfur bond. The three independent Ni-S distances are 2.503, 2,517, and 2.498 Å (all ±0.006 Å) and the Ni-Br distance is 6.190 ± 0.004 Å. The three independent S-C distances are 1.752, 1.737, and 1.697 (all±0.013 Å), not significantly different from the 1.720 ± 0.009 Å found in free thiourea. The C-N distances are likewise not significantly different from the 1.340 (6) A of free thiourea. The thiourea groups are all planar well within experimental error. © 1969, American Chemical Society. All rights reserved.