13965-91-8Relevant articles and documents
Sythesis and Molecular Structure of , and the Isolation of (1-) in Thionyl Chloride
Dell'Amico, Daniela Belli,Calderazzo, Fausto,Marchetti, Fabio,Merlino, Stefano
, p. 2257 - 2260 (1982)
A high-yield synthesis of by treatment of with the stoicheiometric amount of CO in COCl2 is described.The crystal and molecular structure of the tetranuclear compound has been solved by X-ray diffraction methods.It is triclinic, space group P1, with a = 7.015(4), b = 6.830(2), c = 6.684(4) Angstroem, α = 94.4(1), β = 107.5(1), γ = 88.4(1)deg, and Z = 1, and has been refined to R = 0.11 for 989 ' observed ' reflections.The structure consists of discrete molecules with square-planar gold(III) and almost linear gold(I) centres in a chair-like arrangement.The solid compound has a high reactivity towards CO.The platinum(IV) derivative (1-) has been isolated in SOCl2 from the reaction of(1-) with chlorine.
Competitive oxidation and protonation of aqueous monomethylplatinum(II) complexes: A comparison of oxidants
Weinberg, David R.,Labinger, Jay A.,Bercaw, John E.
, p. 167 - 172 (2007)
[PtII(CH3)Cl3]2- (1), generated at 95°C in situ from Cs2[PtIV(CH3) 2Cl4] in an aqueous solution of high chloride concentration and [H+] = 0.2 M, undergoes competitive oxidation versus protonation (kox/kH+) with several oxidants. A first-order dependence on oxidant concentration was determined for both CuCl2 and FeCl3 oxidations of 1, and kox/k H+ was determined to be 191 ± 24 and 14 ± 3. CuCl 2 was shown to catalyze the oxidation of 1 by dioxygen; however, [PtIICl4]2- was also oxidized under these conditions. Anion 1, generated in a mixture of platinum(II) salts, [Cp 2CoIII]2{[PtIICl4] + 1 + [PtII(CH3)2Cl2] (4)}· xNaCl (5), also undergoes competitive oxidation and protonation at room temperature in D2O when in the presence of oxidants. Increasing chloride decreases the ratio kox/kH+ for 1 when Na2[Pt IVCl6] is used as the oxidant, but when CuCl2 is used as the oxidant, added chloride increases kox/kH+. The one-electron oxidants, Na2[IrCl6] and (NH 4)2[Ce(NO3)6], were also shown to oxidize 1.
Kinetics and mechanism for reduction of halo- and haloam(m)ine platinum(IV) complexes by L-ascorbate
Lemma, Kelemu,House, Donald A.,Retta, Negussie,Elding, Lars I.
, p. 98 - 108 (2002)
Reduction of the model platinum(IV) complexes cis-[PtCl4(NH3)2] (1), trans-[PtCl4(NH3)2] (2), trans-[PtCl2(en)2]2+ (3), trans-[PtBr2(NH3)4]2+ (4), [PtCl6]2- (5), and [PtBr6]2- (6) with L-ascorbic acid (H2Asc) in 1.0 M aqueous medium at 25°C in the region 1.75≤pH≤7.20 has been investigated using stopped-flow spectrophotometry. The redox reactions follow the rate law: -d[Pt(IV]/dt=k[H2Asc]tot[Pt(IV)] where k is a pH-dependent second-order rate constant and [H2Asc]tot, the total concentration of ascorbic acid. The pH-dependence of k is attributed to parallel reduction of Pt(IV) by the protolytic species HAsc- and Asc2-. Analysis of the kinetics data reveals that the ascorbate anion Asc2- is up to seven orders of magnitude more reactive than HAsc- while H2Asc is unreactive. Electron transfer from HAsc-/Asc2- to the Pt(IV) compounds is suggested to take place by a mechanism involving a reductive attack on any one of the mutually trans-halide ligands by Asc2- and/or HAsc- forming a halide-bridged activated complex. The rapid reduction of these complexes supports the assumption that ascorbate Asc2- might be an important reductant at physiological conditions for anticancer active Pt(IV) pro-drugs capable of undergoing reductive trans elimination. The parameters ΔH≠ and ΔS≠ for reduction of Pt(IV) with Asc2- have been determined from the study of the temperature dependence of k.
Oxidation of Zeise's salt by [PtCl6]2-: A mechanistic model for hydrocarbon oxidation
Luinstra, Gerrit A.,Wang, Lin,Stahl, Shannon S.,Labinger, Jay A.,Bercaw, John E.
, p. 755 - 756 (1994)
Oxidation of [PtCl3(C2H4)]- by [PtCl6]2- proceeds via a (β-hydroxyethyl)PtII intermediate; its oxidation to the (β-hydroxyethyl)PtIV product involves electron, not alkyl, transfer.
The thermal effects of platinum(II) and palladium(II) complexes with 2-acetyl pyridine and pyridine-2-carbaldehyde N(4)-ethyl-thiosemicarbazones in membrane bilayers
Kovala-Demertzi,Vidjeluc,Demertzis,Siapi,Mavromoustakos
, p. 53 - 58 (2004)
Platinum(II) and palladium(II) complexes with 2-acetyl pyridine and pyridine-2-carbaldehyde N(4)-ethyl-thiosemicarbazones, HAc4Et and HFo4Et respectively were synthesized and found to exhibit a cytotoxic potency in a very low micromolar range and to be able to overcome the cisplatin resistance of A2780/Cp8 cells. The biologically active complexes Pd(Fo4Et)2 (1), Pd(Ac4Et)2 (2), Pt(Fo4Et)2 (3) and Pt(Ac4Et)2 (4) were tested for their perturbation in model membrane bilayers. The aim was to investigate if there is a possible relation between their mechanism of action in membranes with their biological activity. Indeed, it was found that complexes of deprotonated HAc4Et, (2) and (4), are more perturbing than complexes of deprotonated HFo4Et, (1) and (3).
Highly efficient and selective epoxidation of alkenes by photochemical oxygenation sensitized by a ruthenium(II) porphyrin with water as both electron and oxygen donor
Funyu, Shigeaki,Isobe, Takehiko,Takagi, Shinsuke,Tryk, Donald A.,Inoue, Haruo
, p. 5734 - 5740 (2003)
Visible light irradiation of a reaction mixture of carbonyl-coordinated tetra(2,4,6-trimethyl)-phenylporphyrinatoruthenium(II) (RuIITMP(CO)) as a photosensitizer, hexachloroplatinate(IV) as an electron acceptor, and an alkene in alkaline aqueous acetonitrile induces selective epoxidation of the alkene with high quantum yield (Φ = 0.6, selectivity = 94.4% for cyclohexene and Φ = 0.4, selectivity = 99.7% for norbornene) under degassed conditions. The oxygen atom of the epoxide was confirmed to come from a water molecule by an experiment with H218O. cis-Stilbene was converted into its epoxide, cis-stilbeneoxide, without forming trans-stilbeneoxide, trans-Stilbene, however, did not exhibit any reactivity. Under neutral conditions, an efficient buildup of the cation radical of RuIITMP(CO) was observed at the early stage of the photoreaction, while an addition of hydroxide ion caused a rapid reaction with the cation radical to promote the reaction with reversion to the starting RuIITMP(CO). A possible involvement of a higher oxidized state of Ru such as RuIV, RuV, RuVI through a dismutation of the RuIII species was excluded by an experiment with RuVITMP(O)2. Decarbonylation of the Ru complex was also proven to be invalid. A reaction mechanism involving an electron transfer from the excited triplet state of RuIITMP(CO) to hexachloroplatinate(IV) and subsequent formation of OH--coordinated RuIII species, leading to an oxo-ruthenium complex as the key intermediate of the photochemical epoxidation, was postulated.
Transition metal-catalyzed oxidation of l-asparagine by platinum(IV) in acid medium: a kinetic and mechanistic study
Asghar, Basim H.,Altass, Hatem M.,Fawzy, Ahmed
, p. 587 - 594 (2015)
Abstract Kinetic investigations of Pt(IV) oxidation of l-asparagine catalyzed by transition metals with different valencies, namely Ag(I), Pd(II), Cr(III) and Zr(IV), were studied spectrophotometrically in sulfuric acid medium at constant ionic strength and temperature. The reaction was first order in [Pt(IV)], while the orders with respect to the concentrations of Asn, sulfuric acid and transition metal were less than unity over the concentration range studied. The rate constants decreased with increasing ionic strength and dielectric constant, while increasing temperature enhanced the rate. The order of catalytic efficiency was: Ag(I) > Cr(III) > Pd(II) > Zr(IV). A mechanism involving the formation of a complex between the catalyst and substrate is proposed. Oxidation by Pt(IV) is suggested to take place by an inner-sphere mechanism in which Pt(IV) is reduced to Pt(II) on the catalyst-bound substrate in a one-step two-electron transfer process. The oxidation products of Asn were identified as α-formyl acetamide, ammonium ion and carbon dioxide. The rate law associated with the reaction mechanism was deduced. Activation parameters of the reactions were evaluated and discussed.
Kinetics and mechanism of the reductive elimination of oxiranes from "platinahydrins" (Platinum β-hydroxyethyl complexes)
Lintvinenko,Chanysheva,Beskrovnaya,Yanat'Eva,Zamashchikov
, p. 18 - 24 (2010)
The β-hydroxyethyl platinum(IV) derivatives with the general formula [Cl5PtIV-CH2CH(OH)R]2-, where R = H (1) or CH2Cl (2), are fairly stable in aqueous solution at pH 7. In neutral and weakly alkali
C-H activation by aqueous platinum complexes: A mechanistic study
Luinstra, G. A.,Wang, L.,Stahl, S. S.,Labinger, J. A.,Bercaw, J. E.
, p. 75 - 92 (1995)
Detailed mechanistic studies are reported on the oxidation of alkanes by aqueous 2-/2- to alcohols plus alkyl chlorides, via proposed (alkyl)PtII and (alkyl)PtIV intermediates.Reactions of 2- with RI (R = CH3, CH2CH2OH) in water yield 2-, which were isolated as their NMe4 salts.Kinetic rate laws of their decomposition in aqueous chloride solution to ROH and RCl support SN2 displacement by Cl- or H2O as the mechanism of the last step. erythro- and threo-2- are obtained by oxidation of - respectively, and react with Cl- with inversion of stereochemistry at carbon, consistent with the SN2 mechanism. 2- is also obtained by oxidation of Zeise's salt with 2-.Kinetics indicate that attack of water on coordinated ethylene to give a β-hydroxyethyl group precedes oxidation of PtII to PtIV, rather than the reverse order, and that this reaction is a model for the oxidation of (alkyl)PtII to (alkyl)PtIV during alkane functionalization. 195Pt isotopic labeling demonstrates that the oxidation is not accompanied by transfer of the β-hydroxyethyl group from one Pt center to another. Keywords: Platinum; C-H activation
Kinetics and mechanism of the inner-sphere reduction of hexachloroplatinate(IV) by dithionite in acetate buffer
Pal, Biswajit,Gupta, Kalyan K. Sen
, p. 671 - 678 (2013/01/15)
The kinetics of reduction of hexachloroplatinate( IV) by dithionite have been examined spectrophotometrically in sodium acetate-acetic acid buffer medium in the temperature range 288-303 K. The reaction is first order in both platinum(IV) species and dith
