Activation of H-H, HO-H, C(sp 2 )-H, C(sp 3 )-H, and RO-H Bonds by Transition-Metal Frustrated Lewis Pairs Based on M/N (M = Rh, Ir) Couples.

Reaction of the dimers [(Cp*MCl) 2 (μ-Cl) 2 ] (Cp* = η 5 -C 5 Me 5 ) with Ph 2 PCH 2 CH 2 NC(NH( p -Tolyl)) 2 ( H 2 L ) in the presence of NaSbF 6 affords the chlorido complexes [Cp*MCl(κ 2 N , P - H 2 L )][SbF 6 ] (M = Rh, 1 ; Ir, 2 ). Upon treatment with aqueous NaOH, solutions of 1 and 2 yield the corresponding complexes [Cp*M(κ 3 N , N' , P - HL )][SbF 6 ] (M = Rh, 3 ; Ir, 4 ) in which the ligand HL presents a fac κ 3 N , N' , P coordination mode. Treatment of THF solutions of complexes 3 and 4 with hydrogen gas, at room temperature, results in the formation of the metal hydrido-complexes [Cp*MH(κ 2 N , P - H 2 L )][SbF 6 ] (M = Rh, 5 ; Ir, 6 ) in which the N( p -Tolyl) group has been protonated. Complexes 3 and 4 react with deuterated water in a reversible fashion resulting in the gradual deuteration of the Cp* group. Heating at 383 K THF/H 2 O solutions of the complexes 3 and 4 affords the orthometalated complexes [Cp*M(κ 3 C , N , P - H 2 L -H )][SbF 6 ] [M = Rh, 7 ; Ir, 8 , H 2 L -H = Ph 2 PCH 2 CH 2 NC(NH( p -Tolyl))(NH(4-C 6 H 3 Me))], respectively. At 333 K, complexes 3 and 4 react in THF with methanol, primary alcohols, or 2-propanol giving the metal-hydrido complexes 5 and 6 , respectively. The reaction involves the acceptorless dehydrogenation of the alcohols at a relatively low temperature, without the assistance of an external base. The new complexes have been characterized by the usual analytical and spectroscopic methods including the X-ray diffraction determination of the crystal structures of complexes 1 - 5 , 7 , and 8 . Notably, the chlorido complexes 1 and 2 crystallize both as enantiopure conglomerates and as racemates. Reaction mechanisms are proposed based on stoichiometric reactions, nuclear magnetic resonance studies, and X-ray crystallography as well as density functional theory calculations.