Reactivity studies of [Pd2(μ-X)2(PBut3)2] (X = Br, I) with CNR (R = 2,6-dimethylphenyl), H2 and alkynes

Improved syntheses for the dimeric compounds [Pd2(μ-X)2(PBut3)2] (X = Br, I) have been developed and the X-ray crystal structure for the dimer with X = 1 is reported. The reactions of these dimers with CNR (R = 2,6-dimethylphenyl), H2 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 [Pd3(μ-X){ν2-C4(CO2R)4}2][PBut3)Me]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.