STRUCTURAL CHARACTERIZATION OF THE RU(III)BENZONITRILE COMPLEXES (BU4N)[RUCL4(C6H5CN)2] AND [RUCL3(C6H5CN)3]

Tetrabutylammonium trans-bis-(benzonitrile)tetrachlororuthenate(III), C12H28N+.-[RuCl4(C7H5N)2]-, M(r) = 691.60, monoclinic, P2(1)/c, a = 15.627 (2), b = 13.936 (2), c = 17.319 (1) angstrom, beta = 113.66 (1)-degrees, V = 3454.7 angstrom 3, Z = 4, D(x) = 1.330 Mg m-3, lambda(Mo K-alpha) = 0.71069 angstrom, mu = 0.78 mm-1, F(000) = 1436, T = 298 K, R = 0.039 for 4478 observed reflections. There are two independent anions to the asymmetric unit, each with 1BAR symmetry. In one molecule Ru-Cl = 2.356 (2) and 2.348 (1) angstrom and Ru-N = 2.024 (3) angstrom; in the other Ru-Cl = 2.354 (1) and 2.356 (1) angstrom and Ru-N = 2.002 (3) angstrom. mer-Tris(benzonitrile)trichlororuthenium(III) hemibenzonitrile solvate, [RuCl3-(C7H5N)3].0.5C7H5N, M(r) = 568.36, triclinic, P1BAR, a = 9.981 (5), b = 10.895 (5), c = 11.563 (5) angstrom, alpha = 80.86 (5), beta = 87.60 (5), gamma = 88.64 (5)-degrees, V = 1240.2 angstrom 3, Z = 2, D(x) = 1.522 Mgm-3, lambda(Mo K-alpha) = 0.71069 angstrom, mu = 0.96 mm-1, F(000) = 568, T = 298 K, R = 0.050 for 1892 observed reflections. Ru-Cl = 2.322 (3), 2.326 (4) and (trans to nitrile) 2.293 (3) angstrom; Ru-N = 2.011 (8), 2.009 (8) and (trans to Cl) 2.060 (9) angstrom. We conclude from these and related structures that packing forces rather than electronic-pi-back-bonding effects determine the orientation of the benzonitrile ligands.