A Study Of Some Nickel Ii And Cobalt Ii Coordination Complexes With Acetanilides

Author : Gordon G. Hammes
Publisher :
ISBN 13 :
Total Pages : 5 pages
Book Rating : 4.:/5 (227 download)

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Download or read book Relaxation Spectra of Some Nickel (ii) and Cobalt (ii) Complexes written by Gordon G. Hammes and published by . This book was released on 1962 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The rate constants for the formation and dis sociation of Ni(II) and Co(II) complexes with one, two and three glycine, diglycine, or imida zole molecules were determined by the temperature jump technique. The approximate time scale of the reactions studied ranged from 0.1 to 500 msec. The rate-determining step of the complex building reaction, following initial formation of an ion pair, is the dissociation of a water molecule from the inner hydration sphere of the metal ion. The measured rate constants can be normalized with respect to electrostatic and steric factors by dividing out the calculated ion-pair equilibrium constant. The rate constant of dissociation thus obtained is characteristic of a given metal ion, and, in nearly all the re actions studied, was 20 to 25 times greater for Co(II) than for Ni(II). The difference in acti vation energies corresponding to this rate ratio is of the order of magnitude predicted on the basis of crystal-field theories. For glycine, these normalized rate constants tend to increase in reactions involving the higher complexes, in dicating a loosening of the hydration shell due to the fact that the glycine is bound to the metal via the negatively charged carboxyl group. These rate constants are independent of the number of ligands bound if the bonding takes place via uncharged groups. (Author).