Coordination Chemistry of Functional Phosphanes, VI. Rhodium and Iridium Complexes with 2‐(Diphenylphosphophanyl)phenylamido Ligands

Treatment of trans‐[MCl(CO)(PPH3)2] (M = Rh, Ir) with the lithium salts fof 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 single‐crystal X‐ray diffraction to possess an amido‐nitrogen atom in a trigonal‐planar environment. Oxidative addition of H2 to 2b reversibly formed cis‐[IrH2(CO)(PPh3)(‘PNMe’)] (3), in which H2 has added perpendicular to the N–Ir–CO axis. While both 1a,b and 2a, b proved to the completely unreactive toward CO2 at ambient temperature and pressure, reactions of 1a and 2a/b with sulfur dioxide reversibly formed pentacoordinate 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 established by an X‐ray structure analysis of 5a. Complex 5b reacted with dioxygen to form the sulfato compound [Ir(O2SO2)(CO)(‘PNMe’)] (6). Combination of 2a with HCl in CHCl3 at −60°C resulted in protonation of both the iridium and the nitrogen atom to give an ionic chelate 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 observed in the analogous reaction of 2b with hydrogen chloride. NMR spectroscopy showed 8 to exist in CDCl3 solution as a mixture of three Ir–PPh2C6H4N(Me)H‐o rotamers, stabilized by intramolecular –N(Me)H —ClIr hydrogen bonding.