title: Synthesis and characterisation of benzyl phosphino-thioether and -thiolato Pd(II) complexes and their applications in Suzuki coupling reactions.
abstract: The synthesis of the benzyl phosphinothioether derivatives Ph(2)PCH(2)CH(Et)SR and their corresponding palladium complexes are reported, where R = CH(2)Ph, R = CH(2)-3,5-Me-C(6)H(3) and R = 1-CH(2)C(10)H(7)(5). Crystallographic data obtained for the complexes Pd(3)Cl(2) and Pd(4)Cl(2) show intra- and inter-molecular pi-pi interactions between the aromatic rings on the P and S substituents, and NOE experiments for Pd(4)Cl(2) show that these interactions persist in solution. The performance of the phosphinothioether palladium complexes in aryl-aryl cross-coupling reactions is compared with that of the corresponding complex of the parent phosphinothiolato ligand Ph(2)PCH(2)CH(Et)S(-)(1). High turnover numbers up to 2000000 are reported for the coupling of bromobenzene, using the palladium dimer [Pd(1)I](2) as the catalyst precursor. Kinetic studies show a linear dependence of the reaction on catalyst loading. The effect of other variables on the cross-coupling reaction, such as temperature, solvent and base, is also reported.
authors.affiliation: School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, UKCF10 3AT. dervisia@cf.ac.uk
authors.forename: Athanasia
authors.initials: A
authors.lastname: Dervisi
authors.forename: Despina
authors.initials: D
authors.lastname: Koursarou
authors.forename: Li-Ling
authors.initials: LL
authors.lastname: Ooi
authors.forename: Peter N
authors.initials: PN
authors.lastname: Horton
authors.forename: Michael B
authors.initials: MB
authors.lastname: Hursthouse