A computational investigation of the role of the iridium dihydrogen pincer complex in the formation of the cyclic pentamer (NH 2BH 2) 5

Kamalika Ghatak, Kumar Vanka

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Computational studies with density functional theory (DFT) and MP2 have been done to investigate the interaction between the iridium dihydrogen pincer complex: (POCOP)IrH 2 (where POCOP=η 3-1,3(OPtBu 2) 2C 6H 3) and NH 2BH 2, the immediate product of ammonia borane (NH 3BH 3) dehydrogenation. A mechanism has been proposed for an oligomerisation process at the metal centre that involves competition between (i) insertion of an NH 2BH 2 molecule into the (NH 2BH 2) n chain and (ii) termination of the chain leading to the formation of the cyclic (NH 2BH 2) n oligomer. The calculated ΔG 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 (NH 2BH 2) 5 would be formed during NH 3BH 3 dehydrogenation by the (POCOP)IrH 2 catalyst, agreeing with experimental findings. The mechanistic understanding gained has implications for the facile regeneration of ammonia borane.

Original languageEnglish (US)
Pages (from-to)18-29
Number of pages12
JournalComputational and Theoretical Chemistry
Volume992
DOIs
StatePublished - Jul 15 2012
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

Keywords

  • Ammonia borane
  • Hydrogen storage
  • Iridium pincer ligand catalyst
  • Mechanistic studies
  • Oligomerisation cycle

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