75170-81-9Relevant academic research and scientific papers
Arene transition metal complexes in reactions with nucleophilic reagents XIX. Transannular substituent effects in arene-chromium and iron complexes
Litvak, V.V.,Kun, P. P.,Shteingarts, V. D.
, p. 219 - 234 (2007/10/02)
As a result of coordination of chlorobenzene derivatives with the (η-C6H6)Cr+ fragment, the rate of methoxydechlorination was found to increase 14 fold.The effects of the transannular substituent on the rate of methoxydechlorination of (η-C6H5Cl)(η-C6H5X)Cr+A- complexes (1) and on the dissociation constants of (η-C6H5CO2H)(η-C6H5X)Crn acids n = 0 (2), 1+ (3) has been studied.A strong effect of X in the above reaction series has been found, which is defined by the linear correlation equations using the ?p, ?0 and ?R constants for complexes 1, 2 and 3 respectively.The arene-chromium and -iron complexes show a general tendency to increase the mesomeric contribution to the transannular substituent effect with an increase in the electron deficiency in the framework transmitting this effect.Comparison of the effects of X in complexes 1, 2 and 3 leads to the conclusion that there is an intermediate-like transition state in the methoxyde-chlorination of complexes 1, apparently proceeding with intermediate formation of metallorganic analogues of Meisenheimer complexes.
ELECTROCHEMICAL AND ESR KINETICS STUDIES OF ELECTRON TRANSFER IN THE SYSTEM BIS(η6-ARENE)CHROMIUM(0)/BIS(η6-ARENE)CHROMIUM(I)
Li, T. T.- T.,Brubaker, C.H.
, p. 223 - 234 (2007/10/02)
The self-exchange rates and activation parameters in the (η6-arene2Cr0/(η6-arene)2CrI systems (where arene = toluene, benzene, methoxylbenzene, biphenyl, ethylbenzoate and chlorobenzene) have been measured by the ESR line broadening technique in DMSO solvent.The one-electron reduction was investigated by cyclic voltammetry for the series of substituted complexes of (η6-arene)2CrI.A linear correlation was obtained between the measured E1/2 values and the sum of Hammett parameters, Σ?m.For a series of solvents, a linear relationship between log k (the exchange rate constant of (biph)2Cr0/+1) and (1/n2-1/Ds) where n2 and Ds are the optical and static dielectric constants of the solvent medium, respectively, has been observed.This linearity is predicted by Marcus treatment for outer-sphere electron transfer process.A correlation of the oxidation stability of sandwich compounds with their gas-phase ionization potentials is evident from a linear relationship between the oxidation half-potentials E1/2 (or sum of Hammett Σ?m values) and the gas-phase ionization potentials.
