BIMETALLIC MU-OXO COMPLEXES FORMED BY COORDINATION OF THE OXO LIGANDS OF CP2MO=O AND CP2W=O TO RHODIUM(I) AND IRIDIUM(I) CENTERS

The μ-oxo complexes [Cp2M=O—M′ (PPh3)2(CO)]+ (M = Mo, W; Mʹ = Rh, Ir) have been prepared by solvent displacement from [Mʹ(CO)(PPh3)2(CH3CN)]+ by the oxo ligand of Cp2M═O. Crystallographic analysis of the salt [Cp2Mo═O—Rh- (PPh3)2(CO)[BF4]·½C3H6O·½C5H12[P21/c, a = 17.288 (4) Å, b = 13.729 (3) Å, c = 23.168 Å, β = 110.49 (2)°, V= 5151 (2) Å3, Z = 4, R(F) = 6.85%, Rw(F) = 7.42% for 5095 reflections with Fo ≥ 4σ(Fo)] has shown the complex to consist of a square-planar Rh center ligated by the CO, two PPh3 ligands, and the μ-oxo ligand of the Cp2Mo=O moiety. The Mo—O—Rh linkage is nearly linear (Mo—O—Rh = 167.1 (4)°), and the complex appears best described as having a dative interaction of the oxo ligand with the unsaturated Rh center. Spectroscopic data imply similar structures for the other complexes in this series. 1H NMR studies show that the Cp2M═O units of these complexes rapidly exchange with CD3CN solvent and with excess Cp2M=O on the 1H NMR time scale. © 1990, American Chemical Society. All rights reserved.