Homoleptic chelating N-heterocyclic carbene complexes of palladium and nickel
作者:Wolfgang A. Herrmann、Jürgen Schwarz、Michael G. Gardiner、Michael Spiegler
DOI:10.1016/s0022-328x(98)00980-2
日期:1999.2
Homoleptic, dicationic nickel(II) complexes with two cis-chelating N-heterocycliccarbene ligands have been prepared via high yielding, air-stable procedures. Homoleptic and heteroleptic dicationic tetra(carbene) palladium(II) analogues are accessible by the reaction of [cis-CH2}2Pd(OAc)2] with one diazolium diiodide salt precursor or by reacting [cis-CH2}2PdI2] with two equivalents of NaOAc and
Synthesis and structural analysis of palladium biscarbene complexes derived from bisimidazolium ligand precursors
作者:Marion Heckenroth、Antonia Neels、Helen Stoeckli-Evans、Martin Albrecht
DOI:10.1016/j.ica.2005.10.045
日期:2006.4
The palladation of potentially chelating bisimidazolium ligand precursors with palladium acetate gives bridging bimetallic, chelating monometallic, and homoleptic tetracarbene complexes. The coordination mode of the biscarbene ligand has been identified by spectroscopic analysis and crystallographic characterization of representative complexes, including the first example of a biscarbene A-frame structure. Substantial concentrations of free acetate favor the formation of tetracarbene over biscarbene palladium complexes, while in the absence of a base, the concentration of reactants influences the selectivity for bridging bimetallic versus chelating monometallic species. Preliminary kinetic and mechanistic studies indicate that chelating biscarbene palladium acetate complexes are intermediates in the formation of the homoleptic tetracarbene complexes. Probably due to the high trans effect of the biscarbene ligand, such complexes are more efficient palladating agents for bisimidazolium salts than palladium acetate. (c) 2005 Elsevier B.V. All rights reserved.
Metal Complexes of N-Heterocyclic Carbenes—A New Structural Principle for Catalysts in Homogeneous Catalysis
作者:Wolfgang A. Herrmann、Martina Elison、Jakob Fischer、Christian Köcher、Georg R. J. Artus
DOI:10.1002/anie.199523711
日期:1995.11.17
Chelating N-heterocyclic carbene ligands in palladium-catalyzed heck-type reactions
作者:Wolfgang A. Herrmann、Claus-Peter Reisinger、Michael Spiegler
DOI:10.1016/s0022-328x(97)00736-5
日期:1998.4
Synthesis and structural characterization of mixed carbene-carboxylate complexes of palladium(II)
作者:Han Vinh Huynh、Duc Le Van、F. Ekkehardt Hahn、T.S.Andy Hor
DOI:10.1016/j.jorganchem.2004.02.033
日期:2004.5
1′-dimethyl-3,3′-methylenediimidazoline-2,2′-diylidene} palladium(II) bis(pentafluoropropionate) (3) and 1,1′-dimethyl-3,3′-methylenediimidazoline-2,2′-diylidene} palladium(II) bis(heptafluorobutyrate) (4) were obtained. All three complexes were fully characterized by 1H-, 13C- and 19F NMR spectroscopy as well as ESI mass spectrometry. X-ray crystalstructure analyses of complexes 3 and 4 reveal mononuclear