CATIONIC BINUCLEAR A-FRAME COMPLEXES OF RHODIUM(I) AND IRIDIUM(I)

The reaction of bis(diphenylphosphino)methane (DPM) or bis(diphenylarsino)methane (DAM) with an equimolar amount of [Rh(CO)2Cl2]- under CO in the presence of sodium tetraphenylborate yields the binuclear A-frame complexes [Rh2(CO)2(f³-CO)(M-Cl)(L2)2]B(C6H5)4 (L2 = DPM, DAM). Both complexes readily lose CO in solution to give [Rh2(CO)2(³-Cl)(L2)2]B(C6H5)4. Exchange studies using 13CO show that both terminal and bridging CO ligands are labile and that CO exchange and the interconversion of di-and tricarbonyl complexes occur via a bridge-terminal exchange process. Reaction of DPM with [RhCl(c-C8H12)]2 under CO yields [Rh2(CO)2(³-CO)(³-Cl)(DPM)2][Rh(CO)2Cl2]. Sulfur dioxide adds readily and reversibly to [Rh2(CO)2(³-Cl)(L2)2]B(C6Hs)4 to give [Rh2(CO)2(³-SO2)(³-Cl)(L2)2]B(C6H5)4 and on prolonged reaction [Rh2Cl2³-SO2)(DPM)2] is obtained. Reaction of [IrCl(c-C8H12)]2 with DPM and CO produced [Ir2(CO)2(³-CO)(³-Cl)(DPM)2] [Ir(CO)2Cl2] which on treatment with CO and sodium tetraphenylborate yielded [Ir2-(CO)2(³-CO)2Cl(DPM)2]B(C6H5)4. The infrared and 1H, 13C, and 31P NMR spectra of the complexes are discussed. © 1979, American Chemical Society. All rights reserved.