Table of Contents
Metal-Based Drugs
Volume 6 (1999), Issue 4-5, Pages 261-269
http://dx.doi.org/10.1155/MBD.1999.261

[AU(DIEN)Cl]Cl2: Exchange Phenomena Observed by H1 and C13 NMR Spectroscopy

1Department of Chemistry, Birkbeck College, University of London, 29 Gordon Square, London WC1H OPP, UK
2Department of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ, UK

Received 15 September 1998; Accepted 9 October 1998

Copyright © 1999 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The solution behaviour of the square-planar gold(III) complex [Au(dien)Cl]Cl2 (dien = 1,5- diamino-3-azapentane) was investigated by H1 and C13 NMR spectroscopy. We have found that H1 NMR spectra of [Au(dien)Cl]Cl2 are characterised by exchange behaviour over the whole pH range, and some exchange effects are also seen in C13 NMR spectra of the deprotonated hydroxo derivative of the complex in alkaline solution. An exchange rate of > 378 s-1 was determined from H1 NMR spectra at pH2 (coalescence temperature 40C° ). In slightly acidic solutions of the complex, H1 chemical shifts are in accordance with the known deprotonation of the central amine group of the complexed diethylenetriamine ligand. In C13 NMR spectra, two separate sets of resonances are observed for the chloro and the hydroxo complex of gold(III) diethylenetriamine. The hydroxo complex [Au(dien-H)OH]+ shows exchange effects in C13 NMR spectra. Variable temperature studies show the carbon atoms next to the central secondary amine to be inequivalent and each present in two different environments that are in intermediate to fast exchange on the NMR time-scale.