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Iridium Hydride Complexes with Cyclohexyl-Based Pincer Ligands : Fluxionality and Deuterium Exchange

Polukeev, Alexey V. LU ; Marcos, Rocío; Ahlquist, Mårten S G and Wendt, Ola F. LU (2016) In Organometallics 35(16). p.2600-2608
Abstract

Two hydride compounds with aliphatic pincer ligands, (PCyP)IrH2 (PCyP = {cis-1,3-bis[(di-tert-butylphosphino)methyl]cyclohexane}- (1) and (PCyP)IrH4 (2), have been studied, with emphasis on features where such systems differ from arene-based analogues. Both compounds reveal relatively rapid exchange between α-C-H and Ir-H, which can occur via formation of carbene or through demetalation, with nearly equal barriers. This observation is confirmed by deuterium incorporation into the α-C-H position. Complex 1 can reversibly add an N2 molecule, which competes with the α-agostic bond for a coordination site at iridium. The hydrogen binding mode in tetrahydride 2 is discussed on the basis of NMR and... (More)

Two hydride compounds with aliphatic pincer ligands, (PCyP)IrH2 (PCyP = {cis-1,3-bis[(di-tert-butylphosphino)methyl]cyclohexane}- (1) and (PCyP)IrH4 (2), have been studied, with emphasis on features where such systems differ from arene-based analogues. Both compounds reveal relatively rapid exchange between α-C-H and Ir-H, which can occur via formation of carbene or through demetalation, with nearly equal barriers. This observation is confirmed by deuterium incorporation into the α-C-H position. Complex 1 can reversibly add an N2 molecule, which competes with the α-agostic bond for a coordination site at iridium. The hydrogen binding mode in tetrahydride 2 is discussed on the basis of NMR and IR spectra, as well as DFT calculations. While the interpretation of the data is somewhat ambiguous, the best model seems to be a tetrahydride with minor contribution from a dihydrido-dihydrogen complex. In addition, the catalytic activity of 1 in deuterium exchange using benzene-d6 as a deuterium source is presented.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Organometallics
volume
35
issue
16
pages
9 pages
publisher
The American Chemical Society
external identifiers
  • scopus:84983607565
  • wos:000381899600005
ISSN
0276-7333
DOI
10.1021/acs.organomet.6b00324
language
English
LU publication?
yes
id
7d64175b-e110-46e6-90fa-f91e28e80791
date added to LUP
2016-12-02 14:10:42
date last changed
2017-09-17 09:33:34
@article{7d64175b-e110-46e6-90fa-f91e28e80791,
  abstract     = {<p>Two hydride compounds with aliphatic pincer ligands, (PCyP)IrH<sub>2</sub> (PCyP = {cis-1,3-bis[(di-tert-butylphosphino)methyl]cyclohexane}<sup>-</sup> (1) and (PCyP)IrH<sub>4</sub> (2), have been studied, with emphasis on features where such systems differ from arene-based analogues. Both compounds reveal relatively rapid exchange between α-C-H and Ir-H, which can occur via formation of carbene or through demetalation, with nearly equal barriers. This observation is confirmed by deuterium incorporation into the α-C-H position. Complex 1 can reversibly add an N<sub>2</sub> molecule, which competes with the α-agostic bond for a coordination site at iridium. The hydrogen binding mode in tetrahydride 2 is discussed on the basis of NMR and IR spectra, as well as DFT calculations. While the interpretation of the data is somewhat ambiguous, the best model seems to be a tetrahydride with minor contribution from a dihydrido-dihydrogen complex. In addition, the catalytic activity of 1 in deuterium exchange using benzene-d<sub>6</sub> as a deuterium source is presented.</p>},
  author       = {Polukeev, Alexey V. and Marcos, Rocío and Ahlquist, Mårten S G and Wendt, Ola F.},
  issn         = {0276-7333},
  language     = {eng},
  month        = {08},
  number       = {16},
  pages        = {2600--2608},
  publisher    = {The American Chemical Society},
  series       = {Organometallics},
  title        = {Iridium Hydride Complexes with Cyclohexyl-Based Pincer Ligands : Fluxionality and Deuterium Exchange},
  url          = {http://dx.doi.org/10.1021/acs.organomet.6b00324},
  volume       = {35},
  year         = {2016},
}