01930nas a2200217   4500008004100000022001400041245013700055210006900192260007300261300001000334490000800344520107200352653001901424653002101443653003501464653002401499653002601523100002101549700001701570856012501587       2012                        eng d  a2210-271X00aComputational investigation of the role of the iridium dihydrogen pincer complex in the formation of the cyclic pentamer (NH2BH2)(5)0 aComputational investigation of the role of the iridium dihydroge  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcJUL  a18-290 v9923 a<p>Computational studies with density functional theory (DFT) and MP2 have been done to investigate the interaction between the iridium dihydrogen pincer complex: (POCOP)IrH2 (where POCOP = eta(3)-1,3(OPt-Bu-2)(2)C6H3) and NH2BH2, the immediate product of ammonia borane (NH3BH3) dehydrogenation. A mechanism has been proposed for an oligomerisation process at the metal centre that involves competition between (i) insertion of an NH2BH2 molecule into the (NH2BH2)(n) chain and (ii) termination of the chain leading to the formation of the cyclic (NH2BH2)(n) oligomer. The calculated Delta G values show that the competition favours insertion over termination for the cases n = 1 to n = 4 but favours termination for n = 5. The computational studies therefore indicate that the cyclic pentamer (NH2BH2)(5) would be formed during NH3BH3 dehydrogenation by the (POCOP)IrH2 catalyst, agreeing with experimental findings. The mechanistic understanding gained has implications for the facile regeneration of ammonia borane. (C) 2012 Elsevier B.V. All rights reserved.</p>10aAmmonia borane10aHydrogen storage10aIridium pincer ligand catalyst10aMechanistic studies10aOligomerisation cycle1 aGhatak, Kamalika1 aVanka, Kumar  uhttps://library.ncl.res.in/content/computational-investigation-role-iridium-dihydrogen-pincer-complex-formation-cyclic-0