Dihydrogen/dihydride or tetrahydride? an experimental and computational investigation of pincer iridium polyhydrides

Travis J. Hebden, Karen I. Goldberg, Michael D. Heinekey, Xiawei Zhang, Thomas J. Emge, Alan S Goldman, Karsten Krogh-Jespersen

Research output: Contribution to journalArticle

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Abstract

The iridium pincer complexes (PCP)IrH4 (1; PCP = [ 3-1, 3-(CH2PtBu2)2C 6H3]) and (POCOP)IrH4 (2; POCOP = [κ 3-1, 3-(OPtBu2)2C6H 3]) have proven to be effective catalyst precursors for dehydrogenation of alkanes. The complex (POCOP)IrH2 has also been applied successfully as a catalyst for release of H2 from ammonia borane. Investigation of the "tetrahydride" forms of these complexes by solution NMR methods suggests their formulation as dihydrogen/dihydride species. This is in contrast to the solid state structure of 1, determined by neutron diffraction (at 100 K), which indicates a compressed tetrahydride structure with only weak H-H interactions. Complex 1 (C24H 47IrP2) crystallizes in the space group P42, tetragonal, (Z = 2) with a = 11.7006 (19) Å, c = 9.7008(27) Å, and V = 1328.1(5) Å 3. Electronic structure calculations on 1 and 2 indicate that the global minima on the potential energy surfaces in the gas phase are tetrahydride structures; however, the dihydrogen/dihydride forms are only slightly higher in energy (1-3 kcal/mol). A dihydrogen/dihydride species is calculated to be the global minimum for 2 when in solution. The barriers to interconversion between the tetrahydride and dihydrogen/dihydride species are almost negligible.

Original languageEnglish
Pages (from-to)1733-1742
Number of pages10
JournalInorganic Chemistry
Volume49
Issue number4
DOIs
Publication statusPublished - Feb 15 2010

Fingerprint

Iridium
dihydrides
iridium
Boranes
Potential energy surfaces
Catalysts
Alkanes
Dehydrogenation
Neutron diffraction
Ammonia
Electronic structure
Gases
Nuclear magnetic resonance
catalysts
boranes
dehydrogenation
alkanes
neutron diffraction
ammonia
potential energy

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Physical and Theoretical Chemistry

Cite this

Hebden, T. J., Goldberg, K. I., Heinekey, M. D., Zhang, X., Emge, T. J., Goldman, A. S., & Krogh-Jespersen, K. (2010). Dihydrogen/dihydride or tetrahydride? an experimental and computational investigation of pincer iridium polyhydrides. Inorganic Chemistry, 49(4), 1733-1742. https://doi.org/10.1021/ic902163w

Dihydrogen/dihydride or tetrahydride? an experimental and computational investigation of pincer iridium polyhydrides. / Hebden, Travis J.; Goldberg, Karen I.; Heinekey, Michael D.; Zhang, Xiawei; Emge, Thomas J.; Goldman, Alan S; Krogh-Jespersen, Karsten.

In: Inorganic Chemistry, Vol. 49, No. 4, 15.02.2010, p. 1733-1742.

Research output: Contribution to journalArticle

Hebden, TJ, Goldberg, KI, Heinekey, MD, Zhang, X, Emge, TJ, Goldman, AS & Krogh-Jespersen, K 2010, 'Dihydrogen/dihydride or tetrahydride? an experimental and computational investigation of pincer iridium polyhydrides', Inorganic Chemistry, vol. 49, no. 4, pp. 1733-1742. https://doi.org/10.1021/ic902163w
Hebden, Travis J. ; Goldberg, Karen I. ; Heinekey, Michael D. ; Zhang, Xiawei ; Emge, Thomas J. ; Goldman, Alan S ; Krogh-Jespersen, Karsten. / Dihydrogen/dihydride or tetrahydride? an experimental and computational investigation of pincer iridium polyhydrides. In: Inorganic Chemistry. 2010 ; Vol. 49, No. 4. pp. 1733-1742.
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