Contribuição ao estudo da dissociação de complexos de ferro (II) com a-Duminas não simetricas

AUTOR(ES)

Matthieu Tubino

DATA DE PUBLICAÇÃO

1975

RESUMO

In this work, we studied the kinetics of the acid decomposition of the tris-(2-pyridil, a-metil, metilimine) iron (II), Fe(PMM)3, complex in hydrochloric acid solutions, in the concentration range 2 x :10 M to 2.00 M in at temperatures of 52.85 , 56.66 and 61.23 °C. The rate of the pseudo first order reaction was determined by the measurement of the transmittance change, with time, at the maximum absorption (558 mm) of the complex. The acid dependence of the pseudo first order rate constant was interpreted in terms of the mechanism for chelate dissociation, postulated by Basolo and coworkers. The curves of the experimental constants versus acid concentration were separated, at each temperature, into two curves which represent the two possible ways of dissociation, according to the proposal of Vichi and Krumholz for the dissociation of complexes of iron (lI) with unsymmetrical diimines. In order to determine the separated curves a program was elaborated, in FORTRAN IV language, which gave an agreement of about 1.5% between the experimental and calculated curves. A study of the acid decomposition of the complex tris-(2-pyridil,a-metil. imine) iron (II), Fe(PMH)3, was also attempted without success due to the irreproducibility of the rate constants. Using the results of this work and of the literature, a correlation between the energies of the d - p* transitions and the rata constants of decomposition of the complexes was attempted. The interpretation was made in terms of the influence of electronic and steric effects on the rates of dissociation.

ASSUNTO(S)

ferro

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