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Palladium(II) complexes containing mono-, bi- and tridentate carbene ligands. Synthesis, characterisation and application as catalysts in C-C coupling reactions

Citation

Magill, AM and McGuinness, DS and Cavell, KJ and Britovsek, GJP and Gibson, VC and White, AJP and Williams, DJ and White, AH and Skelton, BW, Palladium(II) complexes containing mono-, bi- and tridentate carbene ligands. Synthesis, characterisation and application as catalysts in C-C coupling reactions, Journal of Organometallic Chemistry, 617, (1) pp. 546-560. ISSN 0022-328X (2001) [Refereed Article]

DOI: doi:10.1016/S0022-328X(00)00720-8

Abstract

Palladium complexes of functionalised heterocyclic carbene complexes have been synthesised. Treatment of imidazolium salts with Ag 2 O yields Ag I (carbene) 2 complexes, which act as carbene transfer agents when reacted with palladium salts. In this manner, [Pd(Me)(1-(2-ethylpyridyl)-3-methylimidazolin-2-ylidene)Cl] 2 (4a) and Pd(Me)(1-benzyl-3-methylimidazolin-2-ylidene) 2 Cl (4c) have been prepared from PdMeCl(cod) (cod=1,5-cyclooctadiene) and the appropriate silver complex. Similarly, the reaction of a Ag(carbene) 2 complex with PdCl 2 (MeCN) 2 gives Pd(1-benzyl-3-methylimidazolin-2-ylidene) 2 Cl 2 (4b). The tridentate carbene complex [Pd(Me)(1,3-di(2-picolyl)imidazolin-2-ylidene)]BF 4 (6a) is synthesised via the in situ reaction of the imidazolium salt with Ag 2 O, followed by PdMeCl(cod) and AgBF 4 , whilst [PdCl{1,3-bis(diisopropyl-2-ethylamino)imidazolin-2-ylidene}]BF 4 (6c) is synthesised in an identical manner from PdCl 2 (MeCN) 2 . The chelated complexes [1,1′-dimethyl-3,3′-(1,2-xylylene)diimidazolin-2,2′-diylidene] Pd(II) dibromide (5a), [1,1′-dimethyl-3,3′-(1,3-xylylene)diimidazolin-2,2′-diylidene] Pd(II) dibromide (5b) and Pd(imidazoliophane)Br 2 (5c) have been synthesised via the reaction of the appropriate imidazolium salt with Pd(OAc) 2 . X-ray crystal structures of the imidazolium salt, 1,3-di(2-picolyl)imidazolium chloride (1f) and the complex [Pd(Me)(tetramethylimidazolin-2-ylidene) 2 Cl] (2) are reported. Complex 2 shows square planar coordination with the two carbene ligands trans to each other. The carbene ligands are inclined at 65.3° to the coordination plane. Several complexes proved to be highly stable and efficient catalysts for intermolecular Heck and Suzuki coupling reactions, giving turnover numbers of up to 980 000 (Heck) and 177 500 (Suzuki). © 2001 Elsevier Science B.V.

Item Details

Item Type:Refereed Article
Research Division:Chemical Sciences
Research Group:Other Chemical Sciences
Research Field:Organometallic Chemistry
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Chemical Sciences
Author:Magill, AM (Miss Alison Magill)
Author:McGuinness, DS (Dr David McGuinness)
Author:Cavell, KJ (Professor Kingsley Cavell)
ID Code:22487
Year Published:2001
Web of Science® Times Cited:307
Deposited By:Chemistry
Deposited On:2001-08-01
Last Modified:2011-08-03
Downloads:0

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