Bis(N-heterocyclic carbene) dipalladium complexes: synthesis, solid-state conformational studies and solution behaviour

Journal Publication ResearchOnline@JCU
Willans, Charlotte E.;Anderson, Kirsty M.;Paterson, Martin J.;Junk, Peter C.;Barbour, Leonard J.;Steed, Jonathan W.
Peter Junk
Abstract

New palladium(II) bis(N-heterocyclic carbene) (NHC) complexes have been prepared via metallomacrocyclic AgI ligand transfer agents. Reaction of 1,4-bis(3-isopropylimidazolium)xylene (1a) hexafluorophosphate with Ag2O gives a AgI macrocyclic NHC complex in which two silver ions are sandwiched between two dipodal ligands (2a). The NHC moieties adopt a cisoid conformation relative to one another. Upon transfer to palladium to give [{PdCl2(MeCN)}2(bis-NHC)] (3a) the NHC ligands in the complexes adopt a mixture of cisoid and transoid conformers in the solid state, which have been characterized by X-ray crystallography. In CD3CN solution the cisoid and transoid conformers interconvert and exhibit resonances for a single averaged form.DFT calculations indicate an interconversion barrier of 56 kJ mol–1. In CDCl3 solution two different isomers are observed which have been assigned to isomers of a chloride-bridged dimer (4a) following dissociation of the acetonitrile ligands.

Journal

European Journal of Inorganic Chemistry

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Volume

2009

ISBN/ISSN

1099-0682

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Issue

19

Pages Count

9

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Publisher

Wiley

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EISSN

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DOI

10.1002/ejic.200900219