Reactivity studies of [Pd2(μ-X)2(PBu3t)2] (X = Br, I) with CNR (R=2,6-dimethylphenyl), H2 and alkynes

Improved syntheses for the dimeric compounds [Pd-2(mu-X)(2)(PBu3t)(2)] (X = Br, I) have been developed and the X-ray crystal structure for the dimer with X = I is reported. The reactions of these dimers with CNR (R = 2,6-dimethylphenyl), H-2 and a series of terminal and substituted alkynes are also reported. The dimer with X = Br is an initiator for the catalytic polymerisation of phenylacetylene. The product of the dimers with disubstituted alkynes results in the synthesis of trimeric species with formula [Pd-3(mu-X)(4){eta(2)-C-4(CO2R)(4)}(2)][(PBu3Me)-Me-t](2) (X = Br, I; R = Me, Et). The X-ray crystal structure of one of these compounds (when R = Et and X = I) is presented, demonstrating that the palladium dimers assist the C-C coupling of the alkynes. (C) 2000 Elsevier Science S.A. All rights reserved.