Polymer-supported carbene complexes of palladium: Well-defined, air-stable, recyclable catalysts for the Heck reaction

N-Heterocyclic dicarbene chelate complexes of formula [cis-CH2{N(H)C=C(H)N( R)C}(2)PdX2] (X = Br, I; R=(CH2)(n)OH; n = 2, 3) have been prepared and str ucturally characterized (for X=I, n=2). The complexes were immobilized on a functionalized polystyrene support (Wang resin) through one of the oxygen centres. The complexes efficiently catalyze the Heck reaction of activated and non-activated arylbromides, are recyclable under aerobic conditions and exhibit hardly any leaching, which is in line with our theoretical investi gations on ligand dissociation energies related to Pd-0 and Pd-II centres.