In: Dalton Transactions, 2008, p. 6242 - 6249
Palladation of C2-protected diimidazolium salts with Pd(OAc)₂ afforded complexes comprising C4-bound N-heterocyclic dicarbene ligands. The reactivity of these complexes towards Lewis acids (AgBF₄, AgOAc) and Brønsted acids (H₂SO₄, H₃PO₄, HOAc) revealed that abnormal C4 bonding of the carbenes markedly increases the nucleophilicity of the coordinated palladium center as compared to C2...
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In: ChemPhysChem, 2008, vol. 9, no. 13, p. 1829-1831
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In: Organometallics, 2008, vol. 27, no. 13, p. 3161–3171
Direct metalation of C2-protected diimidozolium salts with RhCl₃ or [RhCl(cod)]₂ and KI afforded a series of new rhodium(III) complexes with abnormally C4-bound, cis-chelating NHC ligands. The complexes were isolated as dimetallic species containing two (μ²-I)₃-bridged rhodium(III) centers. In the presence of coordinating ligands such as CH₃CN, PPh₃, or dppe, the dimeric...
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In: Organometallics, 2006, vol. 25, no. 23, p. 5648 -5656
A series of new piano-stool iron(II) complexes comprising mono- and bidentate chelating N-heterocyclic carbene ligands [Fe(cp)(CO)(NHC)(L)]X have been prepared and analyzed by spectroscopic, electrochemical, crystallographic, and theoretical methods. Selectively substituting the L site with a series of ligands going from carbene to pyridine to CO suggests that CO is the strongest π...
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In: Chimia, 2008, vol. 62, no. 4, p. 253-255
Imidazolium-derived palladium dicarbene complexes have been synthesized which feature either normal C(2) carbene bonding or abnormal C(4) bonding. Comparison of the reactivity of these complexes, in particular towards Lewis acids (H⁺, Ag⁺), indicate consistently that C(4)-bound carbenes are stronger donors than their C(2)-bound analogs. As a consequence of this electronic impact, palladium...
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In: Journal of Organometallic Chemistry, 2007, vol. 692, no. 26, p. 5709-5716
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In: Chemical Communications, 2008, p. 3601-3610
This feature article summarizes the progress achieved thus far in using C4-bound imidazolylidenes as a new class of ligands for transition metals. Since the discovery of this unusual carbene bonding mode in 2001, various rational routes towards complexes containing C4-bound carbenes have evolved. These advances allowed for studying the impact of this new type of ligand on the transition metal...
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In: Angewandte Chemie International Edition, 2007, vol. 46, no. 33, p. 6293 - 6296
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In: Chemical Communications, 2006, p. 4495-4497
Oxidative addition of pyridyl-functionalised 4-iodoimidazolium salts to palladium(0) gives catalytically active complexes in which the N-heterocyclic carbene is bound to the palladium(II) centre in a non-classical bonding mode via C(4).
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In: Chemical Communications, 2005, no. 37, p. 4705-4707
Pyridinium salts similar to those used as ionic liquid solvents readily undergo palladation in the presence of a base, thus giving palladium-pyridylidene N-heterocyclic carbene complexes that are active catalysts for Suzuki-type cross-coupling reactions.
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