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Bis(N‐heterocyclic carbene) Dipalladium Complexes: Synthesis, Solid‐State Conformational Studies and Solution Behaviour
Author(s) -
Willans Charlotte E.,
Anderson Kirsty M.,
Paterson Martin J.,
Junk Peter C.,
Barbour Leonard J.,
Steed Jonathan W.
Publication year - 2009
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200900219
Subject(s) - chemistry , carbene , conformational isomerism , acetonitrile , dimer , palladium , ligand (biochemistry) , dissociation (chemistry) , hexafluorophosphate , solid state , crystallography , stereochemistry , medicinal chemistry , molecule , ionic liquid , organic chemistry , catalysis , biochemistry , receptor
New palladium(II) bis(N‐heterocyclic carbene) (NHC) complexes have been prepared via metallomacrocyclic Ag I ligand transfer agents. Reaction of 1,4‐bis(3‐isopropylimidazolium)xylene ( 1a ) hexafluorophosphate with Ag 2 O gives a Ag I 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 [{PdCl 2 (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 CD 3 CN 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 CDCl 3 solution two different isomers are observed which have been assigned to isomers of a chloride‐bridged dimer ( 4a ) following dissociation of the acetonitrile ligands. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)