Computational investigation of the role of the iridium dihydrogen pincer complex in the formation of the cyclic pentamer (NH2BH2)(5)

TitleComputational investigation of the role of the iridium dihydrogen pincer complex in the formation of the cyclic pentamer (NH2BH2)(5)
Publication TypeJournal Article
Year of Publication2012
AuthorsGhatak, K, Vanka, K
JournalComputational and Theoretical Chemistry
Volume992
Pagination18-29
Date PublishedJUL
ISSN2210-271X
KeywordsAmmonia borane, Hydrogen storage, Iridium pincer ligand catalyst, Mechanistic studies, Oligomerisation cycle
Abstract

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.

DOI10.1016/j.comptc.2012.04.020
Type of Journal (Indian or Foreign)

Foreign

Impact Factor (IF)

1.139

Divison category: 
Physical and Materials Chemistry