103Rh NMR spectroscopy and its application to rhodium chemistry

Rhodium is used for a number of large processes that rely on homogeneous rhodium-catalyzed reactions, for instance rhodium-catalyzed hydroformylation of alkenes, carbonylation of methanol to acetic acid and hydrodesulfurization of thiophene derivatives (in crude oil). Many laboratory applications in organometallic chemistry and catalysis involve organorhodium chemistry and a wealth of rhodium coordination compounds is known. For these and other areas, Rh-103 NMR spectroscopy appears to be a very useful analytical tool. In this review, most of the literature concerning Rh-103 NMR spectroscopy published from 1989 up to and including 2003 has been covered. After an introduction to several experimental methods for the detection of the insensitive Rh-103 nucleus, a discussion of factors affecting the transition metal chemical shift is given. Computational aspects and calculations of chemical shifts are also briefly addressed. Next, the application of Rh-103 NMR in coordination and organometallic chemistry is elaborated in more detail by highlighting recent developments in measurement and interpretation of Rh-103 NMR data, in relation to rhodium-assisted reactions and homogeneous catalysis. The dependence of the Rh-103 chemical shift on the ligands at rhodium in the first coordination sphere, on the complex geometry, oxidation state, temperature, solvent and concentration is treated. Several classes of compounds and special cases such as chiral rhodium compounds are reviewed. Finally, a section on scalar coupling to rhodium is provided. Copyright (C) 2004 John Wiley Sons, Ltd.