A mechanistic study on complexes of type mer-[Cr(CO)₃(η²-L–L)(σ-L–L)](where L–L = Ph₂PCH₂PPh₂, Ph₂PNHPPh₂, or Ph₂PNMePPh₂) using spectroscopic and convolutive electrochemical techniques

Abstract

The new complexes rner-[Cr(CO),(q'-L-L) (0-L-L)] [where L-L = Ph,PCH,PPh, (dppm), Ph,P-NHPPh, (dppa) or Ph,PNMePPh, (dppma)] were synthesized by treating [Cr(CO),(C,H,)] (C,H, = cyclohepta-l,3,5-triene) with the appropriate diphosphine. The complexes were characterized by i.r. and by 31P-{1H} and "H-{,lP} n.m.r. spectroscopy. The electrochemical and chemical oxidation of these complexes was investigated and the products identified by electrochemical techniques and by e.s.r. and i.r. spectroscopy. The one-electron oxidation of mer-[Cr( CO),(q2-L-L) (0-L-L)] gives the 17-electron chromium(i) complex mer-[Cr(CO),(q2-L-L)(o-L-L)] +. These chromium(i) complexes have only limited stability and have been shown to follow two reaction pathways, disproportionation (electron transfer) as in equation (i) and intramolecular displacement of CO as in equation (ii). The rates of these reactions increase markedly from L-L = dppm to dppa or dppma. A second one-electron oxidation process [equation (iii)] has been observed but the dications are very unstable and decompose to give solvated Cr2+, free diphosphine, and CO gas.

Data Analysis and Evaluation of the Electrochemical Parameters for the Et Process via Convolutive Voltammetry and Digital Simulation

“…On the other hand, when α = 0.3 the values of Ψ cover the range 0.130 -4.04x10 -5 in case of variation ∆E p from 217. 4 It was found that the value of the heterogeneous rate constant (k s ) of Pb 2+ ion in 0.1M KNO 3 calculated from the working curve established in this work equals (2.25x10 -2 cm.s -1 ) which compare well with the value (2.10x10 -2 cm.s -1 ) reported in literature 10 confirming the accuracy of our method. Also the value of k s for the system Fe 3+ / Fe 2+ calculated in this work (3.41x10 -4 cm.s -1 ) compare well with the value established in literature (3.0 x 10 -4 cm.s -1 ).…”

“…[2][3][4][5][6][7] The electrochemical parameters used for generating the theoretical cyclic voltammograms of the electrochemical reaction …”

Electrochemical Studies and Extraction of Chemical and Electrochemical Parameters of Zn(ii) Ion at Mercury Electrode via Convolutive Voltammetry and Digital Simulation Methods

“…EC mechanism, the backward direction of I 1 convolution does not return to the initial value. 30 On the other hand, in case of a reversible chemical reaction preceeding charge transfer, i.e. CE mechanism, the limiting convoluting current I lim does not produce the plateau value at low scan rate, Fig It was found that, the values of cathodic peak potential, E pc shift towards more cathodic values, with increasing the sweep rate, also, the peak separation (ΔE p ) values increase with increasing the sweep rate.…”

“…[24][25][26][27] The shape of the I 1 -E curve exhibit important feature for the identification of the nature of the electrode process. For a simple rapid charge transfer, the shape of The convolution of the current data with an inverse square root of time, I 1 is defined as: [24][25][26][27][28][29][30] ( 2) where I 1 is the convoluted current at the total elapsed time and i(u) is the experimental current at time u.…”

Voltammetric studies of the electrochemical behaviour of salicylidene-2-aminopyridine at a hanging-mercury-drop-electrode

“…Convolution and deconvolution procedures were carried out according to the method described earlier (10). The convolution logarithmic analysis was carried out on the basis of the following general equations ' and ~r e s h stock solution of tetraethylammonium perchloia;e (TEAP) (0.1 mol dm-3) in dimethylformamide (DMF) was prepared.…”