Bis(triphenylphosphine)palladium(II) dichloride, …
A series of isolated enzymes having key metabolic functions have been found to be inhibited by simple and complex palladium salts. The strongest inhibition (i value for palladium(II) chloride = 0.16 µmol/litre) was found for creatine kinase, an important enzyme of energy metabolism.
Bis(triphenylphosphine)palladium chloride is a ..
Many palladium-organic complexes have an antineoplastic potential similar to that of -dichloro-2,6-diaminopyridine-platinum(II) (-platinum, an anticancer drug).
The chemical nature and thermodynamics of palladium minerals and aqueous species suggest that palladium is mobile as hydroxide, chloride and bisulfide complexes, depending on pH, oxygen fugacity, ligand concentration and temperature. Hydroxide complexes appear to predominate over chloride complexes at near-neutral to basic pH, even at high chlorinities (5 mol Cl-/litre). The data suggest that the predominant inorganic form of palladium in fresh waters may be the neutral hydroxide species. Bisulfide complexing ([Pd(HS)4]2-) and mixed bisulfide-hydroxide complexes may be important under similar pH conditions. In seawater (near pH 8), it is currently not clear whether the chloride or the hydroxide complex will predominate (Wood, 1991). The dominant chloride species is PdCl42-. Complexes of palladium with carbonate, bicarbonate, phosphate, sulfate and fluoride ions are predicted to be weak (Mountain & Wood, 1987, 1988).
Bis(triphenylphosphine)palladium chloride - Wikipedia
The dimerization of isoprene is complicated as dimerization can afford a number of isomeric octatrienes depending on whether the two isoprene units couple in a head-to-head, head-to-tail or tail-to-tail fashion. The reaction of isoprene in acetone catalyzed by 1 (100-110 °C, 6-8 h) is reported to afford exclusively the tail-to-tail coupling product, 2,7-dimethyl-1,3,7-octatriene (2, R = Me, 75% yield) (). 2-Ethyl-buta-1,3-diene reacts similarly to give 2,7-diethyl-1,3,7-octatriene (2, R = Et, 75% yield). The reaction with 2,3-dimethyl-buta-1,3-diene catalyzed by 1 is not as efficient and gives a 2:3 mixture of 2,3,6,7-tetramethyl-1,3,7-octatriene and 2,3,7-tetramethyl-6-methylene-1,7-octadiene in 75% combined yield but at low conversion (10%). Other palladium catalyst systems dimerize isoprene in a manner quite similar to 1. For example, good yields of 2,7-dimethyl-1,3,7-octatriene are obtained from the dimerization of isoprene using dibromo(diphos)palladium(II)/sodium phenoxide in the presence of phenol (89%), or alternatively, using di(acetylacetonate)palladium(II)/triphenylphosphine system in the presence of -methoxybenzaldehyde (89%). In contrast, the dimerization of isoprene by the cationic (methallyl)palladium(II) complex, [Pd(cod)(methallyl)]PF, in the presence of 1 equiv of tricyclohexylphosphine affords predominantly the tail-to-head isoprene dimer, (,) ,6-dimethyl-1,3,6-octatriene (72% yield).
Bis(triphenylphosphine)palladium(II) chloride (15.2% …
Many of the adverse effects of palladium compounds are mediated by binding to (see section 6.6) and inhibiting enzymes. Studies with a number of isolated enzymes from different animal systems and with distinct metabolic functions demonstrated that Pd2+ compounds had a high inhibition potential (Table 26). The strongest inhibition was found for creatine kinase (i value of 0.16 µmol/litre for palladium(II) chloride), an important enzyme of energy metabolism. In this case, inhibition was accompanied by a marked increase in electrophoretic mobility of the enzyme, possibly indicating conformational changes (Liu et al., 1979b). Another study suggests as a mechanism of inhibition the replacement of Fe2+ with Pd2+ at the active site of prolyl hydroxylase and the formation of strong complexes (Rapaka et al., 1976).
Bis(triphenylphosphine)palladium(II) chloride | 13965 …
Bis(triphenylphosphine)(maleic anhydride)palladium(0) (1) catalyzes dimerization of 1,3-butadiene in aprotic solvents such as benzene (120 °C, 7 h, 64%), THF (115 °C, 7 h, 82%), and acetone (115 °C, 7 h, 86%) to give predominantly ()-1,3,7-octatriene (2, R = H) (). Surprisingly, it is reported that bis(triphenylphosphine)(dimethylfumarate)palladium(0), bis(triphenylphosphine)(-benzoquinone)palladium(0), and tetrakis (triphenylphosphine)palladium(0), are almost completely ineffective under similar reaction conditions. However, 1,3-butadiene can also be efficiently dimerized by a variety of other catalyst systems, including via complementary reaction modes; for example, an aminophosphinite-modified nickel(0) catalyst gives the isomeric 1,3,6-octatriene in 95% yield.