@article {2521, title = {Inactivity of iridium-triphenylphosphine complexes for catalytic imine hydrogenation: formation of neutral, dihydrido-ortho-metallated species}, journal = {Reaction Kinetics and Catalysis Letters}, volume = {98}, number = {2}, year = {2009}, note = {ISI Document Delivery No.: 519XSTimes Cited: 0Cited Reference Count: 32Marcazzan, Paolo James, Brian R.}, month = {Dec}, pages = {193-204}, type = {Article}, abstract = {Reactions of cis,trans,cis-[Ir(H)(2)(PPh3)(2)(MeOH)(2)]PF6 in MeOH with the imines Ph(R{\textquoteright})C=NR under 1 atm H-2 precipitate the neutral, Ir(III)-dihydrido complexes [Ir(H)(2){RN=C(R{\textquoteright})(o-C H-6(4))}(PPh3)(2)], where R = alkyl or benzyl, and R{\textquoteright} = Ph, H, or Me; the dihydrides are well characterized through elemental analysis, NMR and IR data and, in one case, with the imine Ph2C=NCH2Ph, an X-ray structure. These products are formed via intermediate ortho-metallated species, exemplified by [Ir(H){PhCH2N=CPh(o-C H-6(4))}(PPh3)(2)(MeOH)]PF6 in the case of the Ph2C=NCH2Ph reaction; the intermediate then reacts with H-2 (via net heterolytic cleavage: H-2 -> H- + H+) to give the neutral dihydride and HPF6 as co-product. The {\textquoteright}unique{\textquoteright} imine PhCH=NPh, under the same conditions, does not form a dihydride and instead is readily catalytically hydrogenated to PhCH2N(H)Ph; remarkably, we have shown previously that this imine is {\textquoteright}unique{\textquoteright} within the corresponding Rh system in that no catalytic hydrogenation occurs because the amine product {\textquoteright}poisons{\textquoteright} the Rh centre by coordination through the N-phenyl ring.}, keywords = {CHEMISTRY, DIHYDROGEN, H-2, Hydrido-complexes, IMINE HYDROGENATION, Ortho-metallation, PROTONS, TRANS-INFLUENCE, xx Iridium phosphine complexes}, isbn = {0133-1736}, url = {://000271803800001}, author = {Marcazzan, P. and James, Brian R.} }