Evidence for a Chelate-Induced Changeover in the Substitution Mechanism of Aquated Copper(II). Volume Profile Analyses of Water Exchange and Complex-Formation Reactions - Research portal of Justus Liebig University Giessen:

Journal article

Evidence for a Chelate-Induced Changeover in the Substitution Mechanism of Aquated Copper(II). Volume Profile Analyses of Water Exchange and Complex-Formation Reactions

Authors list: Powell, DH; Merbach, AE; Fabian, I; Schindler, S; Vaneldik, R

Publication year: 1994

Pages: 4468-4473

Journal: Inorganic Chemistry

Volume number: 33

Issue number: 20

ISSN: 0020-1669

DOI Link: https://doi.org/10.1021/ic00098a011

Publisher: American Chemical Society

Abstract:
The substitution behavior of aquated Cu(II) ions is strongly affected by the presence of the tren (2,2',2''-triaminotriethylamine) chelate. The kinetics and mechanism of solvent (water) exchange and of a series of complex-formation reactions of Cu(tren)H2O2+ were studied in detail at pressures up to 200 MPa using O-17 NMR and T-jump techniques. The water exchange rate on the pentacoordinate Cu(tren)H2O2+, k(ex)(298) = (2.39 +/- 10.09) x 10(6) s(-1), is over 3 orders of magnitude slower than on the hexacoordinate CU(H2O)(6)(2+). The reported volumes of activation strongly support the operation of an associative interchange (I-a) mechanism, viz. -4.7 +/- 0.2 cm(3) mol(-1) for water exchange and between -4.7 and -10 cm(3) mol(-1) for complex-formation and reverse aquation reactions involving pyridine and substituted pyridines. The latter results are used to construct volume profiles for the complex-formation reactions that further illustrate the volume collapse that occurs in going to the transition state for both reactions. The results are discussed with reference to earlier data reported in the literature. It is concluded that a chelate such as tren can induce a mechanistic changeover on labile aquated metal ions.

Authors/Editors

- Uni.-Prof. Dr. Siegfried Adolf Schindler

Citation Styles

Harvard Citation style: Powell, D., Merbach, A., Fabian, I., Schindler, S. and Vaneldik, R. (1994) Evidence for a Chelate-Induced Changeover in the Substitution Mechanism of Aquated Copper(II). Volume Profile Analyses of Water Exchange and Complex-Formation Reactions, Inorganic Chemistry, 33(20), pp. 4468-4473. https://doi.org/10.1021/ic00098a011

APA Citation style: Powell, D., Merbach, A., Fabian, I., Schindler, S., & Vaneldik, R. (1994). Evidence for a Chelate-Induced Changeover in the Substitution Mechanism of Aquated Copper(II). Volume Profile Analyses of Water Exchange and Complex-Formation Reactions. Inorganic Chemistry. 33(20), 4468-4473. https://doi.org/10.1021/ic00098a011