COORDINATION CHEMISTRY OF FUNCTIONAL PHOS PHANES .3. RHODIUM AND IRIDIUM COMPLEXES WITH 2-(DIPHENYLPHOSPHANYL)PHENOLATO AND 2-(DIPHENYLPHOSPHANYL)THIOPHENOLATO LIGANDS

Treatment of trans-MCl(CO)(PPh(3))(2) (M = Rh, Ir) with the sodium der ivatives of the ortho-substituted bidentate hybrid ligands 2-Ph(2)PC(6 )H(4)XH ('PXH'; X = O, S) smoothly produced the chelate complexes M(CO )(PPh(3))('eta(2) = PX'), M/X = Rh/O (1a), Ir/O (2a), Rh/S (1b), Ir/S (2b), of which the rhodium compound 1a was fully characterized by sing le-crystal X-ray analysis. Complexes 1 and 2 reacted with SO2 to give adducts containing reversibly bound SO2 ligands, M(SO2)(CO)(PPh(3))('e ta(2)-PX'), M/X = Rh/O (3a), Ir/O (4a), Rh/S (3b), Ir/S (4b). Oxidativ e addition of H-2 to iridium complexes 2a and 2b reversibly formed cis -dihydrides, IrH2(CO)(PPh(3))('eta(2)-PO') (5a) and IrH2(CO)(PPh(3))(' eta 2-PS') (5b), respectively. The ring-opened derivative IrHCl2(CO)(P Ph(3))('eta(1)-POH') (6a) was formed on combination of 2a with HCl, in CDCl3, between -60 and +20 degrees C. In solution, 6a proved to be st able only in the presence of excess HCl and otherwise slowly transform ed by elimination of HCl and ring-closure into IrH(Cl)(CO)(PPh(3))('et a(2)-PO') (7a). NMR spectroscopy and X-ray crystallography showed 6a t o exist as Ir-'POH' rotamers in which the OH group is hydrogen-bonded to either the chloro ligand trans to Ir-H or both the chloro and the h ydride ligand of the cis-H-Ir-Cl moiety. Ring-opening protonation of t he thiolate function did not occur in reactions of iridium complex 2b with HCl or CF3CO2H, giving IrH(Y)(CO)(PPh(3))('eta 2-PS') with Y = Cl (7b) or OC(O)CF3 (8b).