Palladium diphenyl-2-pyridylphosphine complexes

Abstract

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.