RHENIUM DIHYDROGEN COMPLEXES AND LONG H-H INTERACTIONS - X-RAY-DETERMINED SINGLE-CRYSTAL STRUCTURES OF RECL(ETA(2)-H2)(PH2PCH2CH2PPH2)2 THFAND [REO2(PH2PCHCHPPH2)2][REO4]

Reduction of ReCl5 in tetrahydrofuran under Ar with 4 equiv of Na in t he presence of bidentate tertiary phosphines (L2) yields complexes of the form ReCl(eta2-H-2)(L2)2, L2 = PPh2CH2CH2PPh2 (1), and L2 = PPh2CH CHPPh2 (2). A similar reduction of ReCl5 in the presence of the monode ntate ligand PMe2Ph affords mixtures of ReH3(PMe2Ph)4 and the cation [ ReH4(PMe2Ph)4]+. The metal-bonded H atoms in complexes 1 and 2 display T1 (min) times of 43 (5) and 29(4) ms, respectively, at 200 MHz. This suggests a long H-H interaction. The single-crystal X-ray structures of complexes 1.THF and [ReO2(PPh2CHCHPPh2)2][ReO4] (3) are reported. C rystal data: compound 1.THF, monoclinic, space group P2(1)/c, a = 11.4 72(4) angstrom, b = 13.468(2) angstrom, c = 17.339(5) angstrom, beta = 96.02(1)-degrees, V = 2664.1(4) angstrom3, Z - 2, R - 0.041 (R(w) = 0 .058) for 288 parameters and 2323 unique data having F(o) > 3sigma(F(o )2); compound 3, triclinic, space group, P1BAR, a = 9.946(1) angstrom, b = 11.744(3) angstrom, c = 12.506(2) angstrom, alpha = 70.59(2)-degr ees, beta = 73.46(1)-degrees, gamma = 65.72(1)-degrees, V - 1237.0(3) angstrom3, Z = 1, R = 0.038 (R(w) = 0.055) for 310 parameters and 2582 unique data having F(o) > 3sigma(F(o)2). The geometries of 2 and the cation in 3 are those of distorted octahedra with the Re atoms situate d on inversion points. In 1, there is 50% disorder between the trans C l- and the eta2-H-2 (not located) ligands. Important distances for 1: Re-Cl at 2.574(6) angstrom and, Re-P(1) and Re-P(2) at 2.388(5) and 2. 399(3) angstrom, respectively, with a P(1)-Re-P(2) angle of 80.3(1)-de grees. Core distances for 3: Re-O(101) at 1.788(6) angstrom and Re-P(1 ) and Re-P(2) at 2.476(2) and 2.473(2) angstrom, respectively, with a P(1)-Re-P(2) angle at 81.18(8)-degrees. The tetrahedral anion in 3, [R eO4]-, is located near an inversion point and was refined at 50% occup ancy. Here Re-O bond distances range from 1.60(7) to 1.77(2) angstrom.