Synthesis and chemistry of diphenyl-2-pyridyIphosphine complexes of palladium(o). X-Ray characterisation of Pd(Ph2Ppy)2-(η2-DMAD) and fra/w-Pd(Ph2Ppy)2(PhC=CH2)(CF 3CO2)

Article abstract of DOI:10.1039/a908050c

The zerovalent complexes Pd(Ph₂Ppy)₃1 and Pd(Ph₂Ppy)₂(dba) 2, where Ph₂Ppy is diphenyI-2-pyridylphosphine and dba = /;ww, /ra-dibenzylideneacetone, have been synthesized and characterised. Reactions of 1 with alkynes have been studied and the dimethyl acetylenedicarboxylate complex Pd(Ph₂Ppy)₂(η²-DMAD) 3, where DMAD is dimethyl acetylenedicarboxylate, isolated and structurally characterised. The complexes /ra;w-Pd(Ph₂Ppy)₂(PhO=CH₂)X, X = CF₃CO₂^- 4 or Cl^- 5, and //w;s-Pd(Ph₂Ppy)₂{CO(CH₃)C=CH₂}Cl 6 result from oxidative addition of phenylacetylene/CF₃CO₂H, phenylacetylene/Et₃NHCl and methacryloyl chloride respectively to 1, and the crystal structure of 4 is presented. The alkenyl ligand is bound to palladium through the a carbon in 4. Insertions into the M-C bond of the vinyl complexes have been studied. No isolable insertion product is obtained with carbon monoxide although the complex is active for the catalytic alkoxycarbonylation of phenylacetylene to 2-phenylpropenoate. Propadiene inserts into the Pd-C bond in 4 to give the cationic rc-allyl complex [Pd(Ph₂Ppy)₂{η³-C₃H ₄C(Ph)=CH₂}][CF₃CO₂] 7. The complex Pd(Ph₂Ppy)₃ is found to catalyse the vinylation of Ph2Ppy to the corresponding 2-propenylphosphonium trifluoromethanesulfonate. The Royal Society of Chemistry 2000.