22542-10-5Relevant articles and documents
Synthesis and Reactions of Platinum(III) Complexes with Protoporphine Ligands in Mixtures of Acetic and Sulfuric Acids
Lomova,Andrianova
, p. 283 - 287 (2003)
Unusual stable platinum complexes (Cl)PtIIIPwere obtained by the reaction of K2[PtCl6] with porphyrin H2P (full methyl ethers of proto-, meso-, deutero-, and hematoporphyrin) in a 1:2 molar ratio in boiling pyridine. The forms of existence, kinetics and mechanism of dissociation of metal porphyrins in AcOH-(0.3-2.1) M H2SO 4 mixtures were studied at 300-330 K. The reaction has first-order with respect to metal porphyrin, low E values (21-48 kJ/mol), and negative ΔS≠ values (-145- to -224 J mol-1 K -1). The dependence of the formal first-order rate constants on H2SO4 concentration is linear at low values of this latter (up to 1.5 M). The mechanism of the electron density redistribution produced by functional substitution in β positions of the macroring was studied to establish that the character of the dependence of the dissociation rate on the macroring nature is determined by restricted π-electron density transfer from the metal atom to a coordinated N atom.
Single-crystal nanowires of platinum can be synthesized by controlling the reaction rate of a polyol process
Chen, Jingyi,Herricks, Thurston,Geissler, Matthias,Xia, Younan
, p. 10854 - 10855 (2004)
Platinum nanowires of ～100 nm in length and 5 nm in diameter have been synthesized by reducing H2PtCl6 with ethylene glycol in the presence of poly(vinyl pyrrolidone) (PVP) and a trace amount of Fe3+ or Fe2+. The wires were generated at the final stage of the synthesis, which involved the formation of several intermediate species. The Fe3+ or Fe2+ ions had dual functions in the synthesis: they induced aggregation of Pt nanoparticles into larger structures that served as the nucleation sites, and they greatly reduced the reaction rate and supersaturation level to induce anisotropic growth. The reaction mechanism was studied by X-ray photoelectron spectroscopy (XPS) and UV-vis spectral analysis. The Pt nanowires could be readily separated from the surfaces of the agglomerates by sonication and obtained as pure samples by centrifugation. Copyright
Electron transfer. 144. Reductions with germanium(II)
Babich, Olga A.,Gould, Edwin S.
, p. 4119 - 4122 (2008/10/08)
Solutions 0.2-0.4 M in Ge(II) and 6 M in HCl, generated by reaction of Ge(IV) with H3PO2, are stable for more than 3 weeks and can be diluted 200-fold with dilute HCl to give GeCl3- preparations to be used in redox studies. Kinetic profiles for the reduction of Fe(III) by Ge(II), as catalyzed by Cu(II), implicate the odd-electron intermediate, Ge(III), which is formed from Cu(II) and Ge(II) (k = 30 M-1 s-1 in 0.5 M HCl at 24 °C) and which is consumed by reaction with Fe(III) (k = 6 x 102 M-1 s-1). A slower direct reaction between Ge(II) and Fe(III) (k = 0.66 M-1 s-1) can be detected in 1.0 M HCl. The reaction of Ge(II) with I3- in 0.01-0.50 M iodide is zero order in oxidant and appears to proceed via a rate-determining heterolysis of a Ge(II)-OH2 species (k = 0.045 s-1) which is subject to H+-catalysis. Reductions of IrCl62- and PtCl62- by Ge(II) are strongly Cl--catalyzed. The Ir(IV) reaction proceeds through a pair of 1e- changes, of which the initial conversion to Ge(III) is rate-determining, whereas the Pt(IV) oxidant probably utilizes (at least in part) an inner-sphere Pt(IV)-Cl-Ge(II) bridge in which chlorine is transferred (as Cl+) from oxidant to reductant. The 2e- reagent, Ge(II), like its 5s2 counterpart, In(I), can partake in 1e- transactions, but requires more severe constraints: the coreagent must be more powerfully oxidizing and the reaction medium more halide-rich.
