X-ray absorption spectroscopy in coordination chemistry

X-ray absorption spectroscopy (XAS) is one of the premier tools for investi gating the local structural environment of metal ions. XAS can be divided i nto X-ray absorption near edge structure (XANES), which provides informatio n primarily about geometry and oxidation state, and extended X-ray absorpti on tine structure (EXAFS) which provides information about metal site ligat ion. One of the key attractions of XAS is that it can be used regardless of the physical form of the sample,and in particular it can be used to study non-crystalline materials. Consequently, XAS has come to be widely utilized by the biochemistry and materials science communities. Recently, however, it has become clear that there are numerous questions of interest to coordi nation chemists that can be addressed using XAS. In this contribution, the physical basis of XAS is reviewed, the advantages and limitations of the te chnique are discussed, and several examples of the applications of XAS to c oordination chemistry are presented. The prospects for future applications of XAS are summarized. (C) 1999 Elsevier Science S.A. All rights reserved.