SYNTHESIS AND MOLECULAR-STRUCTURE OF [(ME(3)SI)(2)P(ME(2)GA)(2)PME](2) - A PHOSPHINOGALLANE CONTAINING A P-P BOND

The Me(3)Ga-PMe(3) Lewis acid-base adduct has been prepared by reactio n of Me(3)Ga with PMe(3) in toluene and characterized by H-1 NMR, P-31 NMR, melting point, elemental analyses (C and H), and single crystal X-ray diffraction. The adduct, possessing approximate C-3v symmetry, c rystallizes in the orthorhombic space group Pnma (No. 62) with unit ce ll parameters a = 12.704(2) Angstrom, b = 11.1736(9) Angstrom, c = 7.8 059(6) Angstrom, D-calcd = 1.14 g/cm(3), and V = 1114 Angstrom(3) for Z = 4. Refinement converged at R = 0.048, R(w) = 0.062 for 482 observe d reflections. The Ga-P distance in Me(3)Ga-PMe(3) is 2.455(4) Angstro m. Reaction of Me(3)Ga-PMe(3) with tris(trimethylsilyl)phosphine (P(Si Me(3))(3)) in toluene affords the novel phosphinogallane [(Me(3)Si)(2) P{Me(2)Ga}(2)PMe](2), which has been characterized by H-1 NMR, P-31 NM R, elemental analyses (C and H), IR, and single crystal X-ray diffract ion. This complex resides about a center of symmetry and crystallizes in the triclinic space group P $($) over bar$$ 1 (No. 2) with unit cel l parameters a = 9.983(2) Angstrom, b = 11.628(2) Angstrom, c = 9.859( 1) Angstrom, alpha = 94.06(1)degrees, beta = 106.69(1)degrees, gamma = 91.98(2)degrees, D-calcd = 1.29 g/cm(3), and V = 1091 Angstrom(3), fo r Z = 1. Refinement converged at R = 0.074, R(w) = 0.092 for 1133 obse rved reflections. The mean Ga-P distance in the title compound is 2.44 (4) Angstrom. This bicyclic phosphinogallane consists of two fused pla nar Ga2P3 five-membered rings sharing a common base with a P-P distanc e of 2.25(3) Angstrom.