Addition of C-C and C-H bonds by pincer-iridium complexes

A combined experimental and computational study

David A. Laviska, Changjian Guan, Thomas J. Emge, Miles Wilklow-Marnell, William W. Brennessel, William D. Jones, Karsten Krogh-Jespersen, Alan S Goldman

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

We report that pincer-ligated iridium complexes undergo oxidative addition of the strained C-C bond of biphenylene. The sterically crowded species (tBuPCP)Ir (RPCP = κ3-1,3-C6H3(CH2PR2)2) initially reacts with biphenylene to selectively add the C(1)-H bond, to give a relatively stable aryl hydride complex. Upon heating at 125 °C for 24 h, full conversion to the C-C addition product, (tBuPCP)Ir(2,2′-biphenyl), is observed. The much less crowded (iPrPCP)Ir undergoes relatively rapid C-C addition at room temperature. The large difference in the apparent barriers to C-C addition is notable in view of the fact that the addition products are not particularly crowded, since the planar biphenyl unit adopts an orientation perpendicular to the plane of the RPCP ligands. Based on DFT calculations the large difference in the barriers to C-C addition can be explained in terms of a "tilted" transition state. In the transition state the biphenylene cyclobutadiene core is calculated to be strongly tilted (ca. 50°-60°) relative to its orientation in the product in the plane perpendicular to that of the PCP ligand; this tilt results in very short, unfavorable, non-bonding contacts with the t-butyl groups in the case of the tBuPCP ligand. The conclusions of the biphenylene studies are applied to interpret computational results for cleavage of the unstrained C-C bond of biphenyl by (RPCP)Ir.

Original languageEnglish
Pages (from-to)16354-16365
Number of pages12
JournalDalton Transactions
Volume43
Issue number43
DOIs
Publication statusPublished - Nov 21 2014

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Iridium
Ligands
Discrete Fourier transforms
Hydrides
Heating
Hydrogen
Temperature
diphenyl

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Medicine(all)

Cite this

Laviska, D. A., Guan, C., Emge, T. J., Wilklow-Marnell, M., Brennessel, W. W., Jones, W. D., ... Goldman, A. S. (2014). Addition of C-C and C-H bonds by pincer-iridium complexes: A combined experimental and computational study. Dalton Transactions, 43(43), 16354-16365. https://doi.org/10.1039/c4dt02043j

Addition of C-C and C-H bonds by pincer-iridium complexes : A combined experimental and computational study. / Laviska, David A.; Guan, Changjian; Emge, Thomas J.; Wilklow-Marnell, Miles; Brennessel, William W.; Jones, William D.; Krogh-Jespersen, Karsten; Goldman, Alan S.

In: Dalton Transactions, Vol. 43, No. 43, 21.11.2014, p. 16354-16365.

Research output: Contribution to journalArticle

Laviska, DA, Guan, C, Emge, TJ, Wilklow-Marnell, M, Brennessel, WW, Jones, WD, Krogh-Jespersen, K & Goldman, AS 2014, 'Addition of C-C and C-H bonds by pincer-iridium complexes: A combined experimental and computational study', Dalton Transactions, vol. 43, no. 43, pp. 16354-16365. https://doi.org/10.1039/c4dt02043j
Laviska DA, Guan C, Emge TJ, Wilklow-Marnell M, Brennessel WW, Jones WD et al. Addition of C-C and C-H bonds by pincer-iridium complexes: A combined experimental and computational study. Dalton Transactions. 2014 Nov 21;43(43):16354-16365. https://doi.org/10.1039/c4dt02043j
Laviska, David A. ; Guan, Changjian ; Emge, Thomas J. ; Wilklow-Marnell, Miles ; Brennessel, William W. ; Jones, William D. ; Krogh-Jespersen, Karsten ; Goldman, Alan S. / Addition of C-C and C-H bonds by pincer-iridium complexes : A combined experimental and computational study. In: Dalton Transactions. 2014 ; Vol. 43, No. 43. pp. 16354-16365.
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