Electrochemical Investigation of Potassium Heptacyanorhenate(III) in Aqueous Solution

Abstract

The electrochemistry of potassium heptacyanorhenate(lI1) in aqueous solution was studied by cyclic and by rotating disk voltammetry at planar microelectrodes. The results are consistent with a single, reversible electron transfer: Re(CN): + e*Re(CN)$-with Eb = 643 mV us. NHE. A single protonation equilibrium is observed:Re(CN);-+ HC&Re(CN),H3-with pK = 1.31 determined from combined voltammetric and pH data. TheRe-CN bond appears to be kinetically inert, and none of the cyano complexes in other oxidation states of Re claimed in the literature was found in the potential range -2 V to + I V.Introduction. ~ Cyano complexes of rhenium in the oxidation states 0 to VI have been claimed since more than thirty years [l] [2], and the literature is summarized in a review by Gr@h 131. In a more recent paper by Grij'th et al. [4], the existence of many of these species has been questioned, and only two of them, uiz. Re (CN

New Cyanometalate Building Units: Synthesis and Characterization of [Re(CN)7]3- and [Re(CN)8]3-

“…In contrast, [Re(CN) 7 ] 4- rapidly oxidizes in air . The cyclic voltammogram of 1 in acetonitrile displays a [Re(CN) 7 ] 3-/4- redox couple centered at E 1/2 = −1.06 V (Δ E p = 140 mV) versus Cp 2 Fe 0/1+ …”

trans-Dichloro{P,P′-[3,3′-oxybis(m-phenylenemethylene)]bis(diphenylphosphine)}palladium(II)

“…Compound (I) was prepared according to the published method of Marty et al (1987). Crystals were obtained by slow evaporation of a chloroform solution.…”

New Diphosphane Ligands Based on Bisphenol A Backbones − Synthesis and Coordination Chemistry

“…Furthermore, the silicon derivative 4 was synthesized in good yield starting from 4-bromoanisole and dichlorodimethylsilane via a modified two-step route. Compounds 1Ϫ4 were characterized by 1 H, 13 C, and 31 P NMR spectroscopy, as well as by elemental analysis. We have previously reported this synthetic route, focussing on the synthesis and catalytic applicability of a ligand derived from 1,2-diphenylbenzene as the backbone.…”

“…Marty trans-coordinated PdCl 2 complex using 3,3Ј-oxybis[(diphenylphosphanyl)methyl]benzene, which is structurally related to compounds 1Ϫ4. [13] From the reaction of 2 with [PdClCH 3 (cod)] as a starting material, only a singlet at δ ϭ 25.0 ppm was observed in the 31 P NMR spectrum. In the 1 H NMR spectrum, a broad triplet was present at δ ϭ Ϫ0.05 ppm and a singlet at δ ϭ 3.8 ppm was seen in the 13 C NMR spectrum.…”

“…[13] From the reaction of 2 with [PdClCH 3 (cod)] as a starting material, only a singlet at δ ϭ 25.0 ppm was observed in the 31 P NMR spectrum. In the 1 H NMR spectrum, a broad triplet was present at δ ϭ Ϫ0.05 ppm and a singlet at δ ϭ 3.8 ppm was seen in the 13 C NMR spectrum. These observations are clear indications that a trans-coordinated species is present, either monomeric or dimeric.…”