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The zerovalent complexes Pd(Ph2Ppy)31 and Pd(Ph2Ppy)2(dba) 2, where Ph2Ppy is diphenyl-2-pyridylphosphine and dba = trans,trans-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 trans-Pd(Ph2Ppy)2(PhC[double bond, length half m-dash]CH2)X, X = CF3CO2−4 or Cl−5, and trans-Pd(Ph2Ppy)2{CO(CH3)C[double bond, length half m-dash]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 α 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 π-allyl complex [Pd(Ph2Ppy)2{η3-C3H4C(Ph)[double bond, length half m-dash]CH2}][CF3CO2] 7. The complex Pd(Ph2Ppy)3 is found to catalyse the vinylation of Ph2Ppy to the corresponding 2-propenylphosphonium trifluoromethanesulfonate.

The alkoxycarbonyl complexes Pd(Ph2Ppy)2(CO2R)(OAc) where Ph2Ppy is 2-pyridyldiphenylphosphine and R = Me 1, Et 2, i-Pr 3 have been prepared from Pd(OAc)2 and Ph2Ppy in ethanol solution under an atmosphere of CO. Increasing the CO pressure favours the formation of palladium carbonyl species. In the presence of 2 mol equivalents of CF3CO2H, the complex Pd(Ph2Ppy)2(CO2CH3)(CF3CO2) 4 is isolated from methanol. Pd(Ph2Ppy)2(CO2CH3)Cl 5 has been obtained by the reaction of Pd(Ph2Ppy)2Cl2 with NaOCH3 in the presence of CO. 1 and 5 have been crystallographicaly characterised as trans isomers, a geometry confirmed for all the complexes by 13C NMR. The reactivity of the complexes toward alkynes and propadiene has been investigated and the π-allyl complex [Pd(Ph2Ppy)2{η3-C3H4C(CH3)[double bond, length half m-dash]CH2}][O2CCF3] 8 isolated and structurally characterised.

The stoichiometric reaction of diphenyl-2-pyridylphosphine (Ph2PC5H4N-2) and palladium(II) acetate afforded the palladium(I) dimer [Pd2(µ-Ph2PC5H4N)2(OAc)2] 1. Attempts to isolate the monomer, [Pd(µ-Ph2PC5H4N)2(OAc)2], from 2∶1 stoichiometry reactions (Ph2PC5H4N∶Pd), resulted only in the isolation of 1. When >3 mole equivalents of Ph2PC5H4N were used the zerovalent palladium complex [Pd(Ph2PC5H4N)3] was isolated. Other palladium(I) dimers with carboxylic or sulfonic anionic ligands have been prepared by a metathesis reaction of the co-ordinated acetates. The complexes 1 and [Pd2(µ-Ph2PC5H4N)2(O2CCF3)2] 2 have been structurally characterised as head-to-tail dimers. The mononuclear complex [Pd(Ph2PC5H4N)2(O2CCF3)2] has been obtained by reaction of Ph2C5H4N with [Pd(CH3CN)2(O2CCF3)2]. Complex 1 reacts with dimethyl acetylenedicarboxylate to give [Pd2(µ-Ph2PC5H4N)2(OAc)2(µ-MeO2CCCCO2Me)], while attempts to isolate an A-frame carbonyl complex were unsuccessful.