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Structural variation, dynamics, and catalytic application of palladium(II) complexes of di-N-heterocyclic carbene-amine ligands

Houghton, Jennifer, Dyson, Gavin, Douthwaite, Richard E., Whitwood, Adrian C. and Kariuki, Benson M. (2007) Structural variation, dynamics, and catalytic application of palladium(II) complexes of di-N-heterocyclic carbene-amine ligands. Dalton Transactions. pp. 3065-3073. ISSN 1477-9234

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Abstract

A series of palladium(II) complexes incorporating di-NHC-amine ligands has been prepared and their structural, dynamic and catalytic behaviour investigated. The complexes [trans-(k(2)-(CN)-C-tBu(Bn)CN(Bn)C-tBu)PdCl2] (12) and [trans-(kappa(2)-(CN)-C-Mes(H)C-Mes)PdCl2] (13) do not exhibit interaction between the amine nitrogen and palladium atom respectively. NMR spectroscopy between - 40 and 25 degrees C shows that the di-NHC-amine ligand is flexible expressing C-s symmetry and for 13 rotation of the mesityl groups is prevented. In the related C-1 complex [(kappa(3)-(CN)-C-tBu(H)C-tBu)PdCl][CI] (14) coordination of NHC moieties and amine nitrogen atom is observed between -40 and 25 degrees C. Reaction between 12 - 14 and two equivalents of AgBF4 in acetonitrile gives the analogous complexes [trans-(kappa(2)-(CN)-C-tBu(Bn)C-tBu)PdCl2] (12) and [trans-(kappa(CN)-C-2Mes(H)C-Mes)PdCl2] (13) do not exhibit interaction between the amine nitrogen and palladium atom respectively. NMR spectroscopy between -40 ans 25 degrees C shows the di-NHC-amine ligand is flexible expressing C-s symmetry and for 13 rotation of the mesityl groups is prevented. In the related C-1 complex [kappa(3)-(CN)-C-tBu(H)C-tBu)PdCI][CI] (14) coordination of NHC moieties and amine nitrogen atom is observed between -40 and 25 degrees C.Reaction between 12-14 and two equivalents of AgBF4 in acetonitrile gives the analogous complexes [trans-(kappa(2)-(CN)-C-tBu(H)(CPd)-Pd-tBu(MeCN)(2)][BF4](2) (15), [trans-(kappa(CN)-C-2Mes(H)C-Mes)Pd(MeCN)(2)[BF4](2 (16)) and [(kappa(3)-(CN)-C-tBu(H)C-tBu)Pd(MeCN)][BF4](2) (17) indicating that ligand structure determines amine coordination. The single crystal X-ray structures of 12, 17 and two ligand imidazolium salt precursors C-tBu(H)N(Bn)C(H) (tBu)][CI](2) (2) and [C-tBu(H) N(H)C(H)(tBu)][BPh4](2) (4) have been determined. Complexes 12-14 and 15-17 have been shown to be active precatalysts for Heck and hydroamination reactions respectively.

Item Type: Article
Copyright, Publisher and Additional Information: © The Royal Society of Chemistry 2007. In accordance with the publisher's embargo, an author produced version of this paper will be freely available from July 2008.
Keywords: C Coupling reactions, Bis(carbene)pyridine complexes, Intramolecilar hydroamination, Efficient catalysts, Metal-complexes, Heck reaction, Olefins, Amination, Phosphines, Oligomerization
Academic Units: The University of York > Chemistry (York)
Depositing User: Ms Diana Hilmer
Date Deposited: 15 Oct 2007 17:00
Last Modified: 17 Oct 2013 14:14
Published Version: http://dx.doi.org/10.1039/b703248j
Status: Published
Refereed: Yes
Related URLs:
URI: http://eprints.whiterose.ac.uk/id/eprint/3386

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