TRANSITION METAL BOROHYDRIDE COMPLEXES .3. STRUCTURE OF OCTAHYDROTRIBORATOBIS(TRIPHENYLPHOSPHINE)COPPER(I)

The crystal and molecular structure of octahydrotriboratobis(triphenylphosphine)copper(I) has been determined by a threedimensional X-ray crystallographic analysis. The colorless compound crystallizes in the monoclinic system, space group P21/c, with unit cell dimensions a = 11.378 (5) Å, b = 20.66 (1) Å, c = 18.13 (1) Å, β = 127.05 (5)°, and Z = 4. From ~2800 independent observable reflections collected by diffractometer, the structure was solved and has been refined by least-squares techniques to a final value for the discrepancy index, R, of 0.078. The crystal is composed of monomers in which the copper atom is coordinated to two triphenylphosphine ligands (Cu-P = 2.281 ± 0.007 Å, P-Cu-P = 120.0 ± 0.1°) and to two hydrogen atoms on different boron atoms of the B3H8- group (Cu-H = 1.84 ± 0.05 Å; H-Cu-H = 103 ± 2°). These structural features correlate well with results found for other bis(triphenylphosphine)copper(I) complexes and for the octahydrotriborate group in the (OC)4Cr(B3H8)- anion. The geometries of the free and coordinated B3H8- ion are shown to be comparable. The infrared spectra of L2Cu(B3H8) complexes, where L is triphenylphosphine, triphenylarsine, or diphenylmethylphosphine, are discussed with reference to the known Cu-B3H8 attachment. © 1969, American Chemical Society. All rights reserved.