139168-06-2Relevant academic research and scientific papers
Oxidative degradation of the ascorbate anion in the presence of platinum and palladium. Formation and structures of platinum and palladium oxalate complexes
Arendse, Malcolm J.,Anderson, Gordon K.,Rath, Nigam P.
, p. 2495 - 2503 (2008/10/08)
The reactions of [Pt(NO3)2(dppm)] (dppm = bis(diphenylphosphino)methane) and cis-[Pt(NO3)2(PEt3)2] with sodium ascorbate are described. Complexes containing O,O-coordinated ascorbate ligand
Carbon-sulfur bond-forming reductive elimination involving sp-, sp2-, and sp3-hybridized carbon. Mechanism, steric effects, and electronic effects on sulfide formation
Mann, Grace,Baranano, David,Hartwig, John F.,Rheingold, Arnold L.,Guzei, Ilia A.
, p. 9205 - 9219 (2007/10/03)
Palladium thiolato complexes [(L)Pd(R)(SR')], within which L is a chelating ligand such as DPPE, DPPP, DPPBz, DPPF, or TRANSPHOS, R is a methyl, alkenyl, aryl, or alkynyl ligand, and R' is an aryl or alkyl group, were synthesized by substitution or proton-transfer reactions. All of these thiolato complexes were found to undergo carbon-sulfur bond-forming inductive elimination in high yields to form dialkyl sulfides, diaryl sulfides, alkyl aryl sulfides, alkyl alkenyl sulfides, and alkyl alkynyl sulfides. Reductive eliminations forming alkenyl alkyl sulfides and aryl alkyl sulfides were the fastest. Eliminations of alkynyl alkyl sulfides were slower, and elimination of dialkyl sulfide was the slowest. Thus the relative rates for sulfide elimination as a function of the hybridization of the palladium-bound carbon follow the trend sp2 > sp >> sp3. Rates of reductive elimination were faster for cis-chelating phosphine ligands with larger bite angles. Kinetic studies, along with results from radical trapping reactions, analysis of solvent effects; and analysis of complexes with chelating phosphines of varying rigidity, were conducted with [Pd(L)(S-tert-butyl)(Ar)] and [Pd(L)(S- tert-butyl)(Me)]. Carbon-sulfur bond-forming reductive eliminations involving both saturated and unsaturated hydrocarbyl groups proceed by an intramolecular, concerted mechanism. Systematic changes in the electronic properties of the thiolate and aryl groups showed that reductive elimination is the fastest for electron deficient aryl groups and electron rich arenethiolates, suggesting that the reaction follows a mechanism in which the thiolate acts as a nucleophile and the aryl group an electrophile. Studies with thiolate ligands and hydrocarbyl ligands of varying steric demands favor a migration mechanism involving coordination of the hydrocarbyl ligand in the transition state.
Influence of ligands and anions on the rate of carbon monoxide insertion into palladium-methyl bonds in the complexes (P-P)Pd(CH3)Cl and [(P-P)Pd(CH3)(L)]+SO3CF3- (P-P = dppe, dppp, dppb, dppf; L = CH3CN, PPh3)
Dekker, Guido P. C. M.,Elsevier, Cornelis J.,Vrieze, Kees,Van Leeuwen, Piet W. N. M.
, p. 1598 - 1603 (2008/10/08)
The preparation of the neutral complexes (P-P)Pd(CH3)Cl (P-P = 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), 1,4-bis(diphenylphosphino)butane (dppb), 1,1′-bis-(diphenylphosphino)ferrocene (dppf)) and the ionic complexes [(P-P)Pd(CH3)(CH3CN)]+SO3CF 3- (P-P = dppe, dppp, dppb, dppf) is described. The ionic dppb complex was formed as a mixture of monomeric and oligomeric forms, which can be attributed to the length and the flexibility of the backbone of the ligand. The rate of CO insertion into the Pd-CH3 bond in these complexes has been studied. The rate was found to decrease in the order dppb ≈ = dppp > dppf for the neutral complexes with half-life times ranging from 18 to 36 min at 235 K and 25 bar of CO. The dppe complex reacted much slower with a half-life time of 170 min at 305 K. The rate of carbonylation of the Pd-CH3 bond in the cationic complexes was at least 10 times higher than those of the analogous neutral complexes, the order being dppb ≈ dppp ≈ dppf > dppe with half-life times a half-life time of 2.5 min was measured. Carbonylation of the ionic PPh3-coordinated complex [(dppp)Pd(CH3)(PPh3)]+-SO3CF 3- was at least 2.5 times slower than that of the analogous CH3CN-coordinated cationic complex.
