COORDINATION-CHEMISTRY OF FUNCTIONAL PHOSPHANES .6. RHODIUM AND IRIDIUM COMPLEXES WITH 2-(DIPHENYLPHOSPHANYL)PHENYLAMIDO LIGANDS

Treatment of trans-[MCl(CO)(PPh3)(2)] (M = Rh, Ir) with the lithium sa lts of the bidentate hybride ligands 2-Ph2PC6H4N(R)H ['PN(R)H'; R = H, Me] produced the chelate complexes [M(CO)(PPh3)('PNR')] [M/NR = Rh/NH (1a), Ir/NH (2a), Rh/NMe (1b), Ir/NMe (2b)] containing the CO ligand and the NR substituent in mutual trans-arrangement. 2b was shown by si ngle-crystal X-ray diffraction to possess an amido-nitrogen atom in a trigonal-planar environment. Oxidative addition of H-2 to 2b reversibl y formed cis-[IrH2(CO)(PPh3)('PNMe')] (3), in which H-2 has added perp endicular to the N-Ir-CO axis. While both 1a,b and 2a,b proved to be c ompletely unreactive toward CO2 at ambient temperature and pressure, r eactions of 1a and 2a/b with sulfur dioxide reversibly formed pentacoo rdinate SO2 adducts, [M(SO2)(CO)(PPh3)('PNR')] [M/NR = Rh/NH (4a), Ir/ NH (5a), Ir/NMe (5b)] with M-S-bonded pyramidal MSO2 units as establis hed by an X-ray structure analysis of 5a. Complex 5b reacted with diox ygen to form the sulfato compound [Ir(O2SO2)(CO)(PPh3)('PNMe')] (6). C ombination of 2a with HCl in CHCl3 at -60 degrees C resulted in proton ation of both the iridium and the nitrogen atom to give an ionic chela te complex, [IrHCl(CO)(PPh3)('PNH2')]Cl (7), containing one of its NH groups hydrogen-bonded to Ir-Cl. Ring opening of the chelate structure with formation of [IrHCl2(CO)(PPh3)(PPh2C6H4N(Me)H-o)] (8) was observ ed in the analogous reaction of 2b with hydrogen chloride. NMR spectro scopy showed 8 to exist in CDCl3 solution as a mixture of three Ir-PPh 2C6H4N(Me)H-o rotamers, stabilized by intramolecular -N(Me)H ... CIIr hydrogen bonding.