Showing papers by "Penny A. Chaloner published in 2004"

Insertion reactions of SO2 into Pd–OR bonds: preparation of alkyl sulfito complexes of palladium(II)

Abstract: Mononuclear palladium–hydroxo complexes of the type [Pd(N–N)(C6F5)(OH)] [(N–N = 2,2′-bipyridine (bipy), 4,4′-dimethyl-2,2′-bipyridine (Me2bipy), or N,N,N′,N′-tetramethylethylenediamine (tmeda) react with SO2 (1 atm) at room temperature in alcohol (methanol, ethanol, propanol or isopropanol) to yield alkyl sulfito palladium complexes [Pd(N–N)(C6F5)(SO2OR)] (R = Me, Et, Pr or iPr). Similar alkyl sulfito complexes [Pd(N–N)(C6F5)(SO2OR)] (N–N = bis(3,5-dimethylpyrazol-1-yl)methane); R = Me or Et) are obtained when [Pd(N–N)(C6F5)Cl] is treated with KOH in the corresponding alcohol ROH and SO2 is bubbled through the solution. The reaction of [Pd(bipy)(C6F5)(OH)] with SO2 in tetrahydrofuran gives [Pd(N–N)(C6F5)(SO2OH)]. The X-ray diffraction study of [Pd(tmeda)(C6F5)(SO2OPr)] has established the sulfur coordination of the propyl sulfito ligand.

Condensation reactions of monomeric hydroxo palladium complexes with active methyl and methylene compounds

Abstract: Heating a suspension of the monomeric hydroxo palladium complex of the type [Pd(N–N)(C6F5)(OH)] (N–N = bipy, Me2bipy, phen or tmeda) in methylketone (acetone or methylisobutylketone) under reflux affords the corresponding ketonyl palladium complex [Pd(N–N)(C6F5)(CH2COR)]. On the other hand, the reaction of the hydroxo palladium complexes [Pd(N–N)(C6F5)(OH)] (N–N = bipy, phen or tmeda) with diethylmalonate or malononitrile yields the C-bound enolate palladium complexes [Pd(N–N)(CHX2)(C6F5)] (X = CO2Et or CN), and the reaction of [Pd(N–N)(C6F5)(OH)] (N–N = bipy or phen) with nitromethane gives the nitromethyl palladium complexes [Pd(N–N)(CH2NO2)(C6F5)]. [Pd(tmeda)(C6F5)(OH)] catalyses the cyclotrimerization of malononitrile. The crystal structures of [Pd(bipy)(C6F5)(CH2COMe)]·½Me2CO, [Pd(tmeda)(C6F5){CH(CO2Et)2}], [Pd(tmeda)(C6F5){CH(CN)2}] and [Pd(tmeda)(C6F5)(CH2NO2)]·½CH2Cl2 have been established by X-ray diffraction.