Substituted metal carbonyls. XX. Unexpected formation of two diphenylphosphine complexes from the oxidation of pentacarbonylrhenate by chlorodiphenylphosphine. Crystal and molecular structures of eq-Re2(CO)9(PPh2H) and cis-ReCl(CO)4(PPh2H)

Abstract

Oxidation of [Re(CO)5]- by a molar equivalent of PPh2Cl at ca. -70°C yielded three dinuclear complexes, Re2(μ-Cl)(μ-PPh2)(CO)8 (1), Re2(CO)9(PPh2H) (2) and Re2(μ-H)(μ-PPh2)(CO)8 (3), as major products. When PPh2Cl was present in two-fold excess, only 2 and ReCl(CO)4(PPh2H) (4) were isolated. All the complexes were characterized by IR and NMR (1H and 31P) spectroscopy. The crystal structures of 2 and 4 were determined by single-crystal X-ray diffraction analyses. Crystal data: ReCl(CO)4(PPh2H), space group P21/c, a = 11.358(1), b = 10.365(1), c = 14.765(3) Å, β = 96.07(1)°, final R = 0.022 for 1891 observations; Re2(CO)9(PPh2H), space group P21/a, a = 12.709(1), b = 12.072(2), c = 15.462(2) Å, β = 92.14(1), final R = 0.029 for 2093 observations. Complex 2 is the first structurally characterized Re2(CO)9(PR3) complex with the phosphine substituent at the equatorial site. The complex Re2(η-PPh2)2(CO)8 was not detected and there is no evidence of direct nucleophilic attack of the rhenate on chlorodiphenylphosphine. © 1992.