STRUCTURE OF TRANS-[OSH(ETA-2-H2)(PPH2CH2CH2PPH2)2][BF4]

Bis[1,2-bis(diphenylphosphino)ethane](eta(2)-dihydrogen)hydridoosmium(II) tetrafluoroborate, [OsH(C26H24P2)2(H2)][BF4], M(r) = 1076.9, monoclinic, P2(1)/n, a = 17.711 (3), b = 16.937 (3), c = 15.982 (4) angstrom, beta = 102.85 (2)-degrees, V = 4674 (3) angstrom 3, Z = 4, D(m) = 1.54 (flotation in CCl4/C6H12), D(x) = 1.53 g cm-3, graphite-monochromated Mo K-alpha radiation, lambda = 0.71073 angstrom, mu = 29.2 cm-1, F(000) = 2160, T = room temperature, R = 0.049, wR = 0.054, for 4642 observed independent reflections. The crystal structure consists of an OsH(eta-2-H2)(dppe)2 cation and a disordered BF4 anion. The 1,2-bis(diphenylphosphino)ethane ligands (dppe) coordinate to the Os atom creating an apparent pseudo-square-planar complex, if the H- and eta(2)-H2 ligands are disregarded. A hydride ligand has been located in one of the two remaining coordination sites associated with an octahedral coordination geometry although the Os-H1 distance refined to an unacceptably long value of 2.26 (7) angstrom. Electron density believed to be associated with the eta(2)-H2 ligand has been located trans to the hydride ligand at approximately 1.7 angstrom from the Os atom. All attempts to refine the eta(2)-H-2 ligand were unsuccessful.