Iron piano-stool complexes containing NHC ligands outfitted with pendent arms: synthesis, characterization, and screening for catalytic transfer hydrogenation
Abstract
Catalysis is a fundamental technology that is widely used in the food, petrochemical, pharmaceutical, and agricultural sectors to produce chemical products on an industrial scale. Well-defined molecular organometallic species are a cornerstone of catalytic methodology, and the activity and selectivity of these complexes can be modulated by judicious choice of metal and
surrounding ligands. Catalysts containing precious metals such as Pd, Rh, Ir, and Ru are typically very efficient, as related reactions require extremely low catalyst loadings. However, precious metals have very limited availability and are
subsequently rather expensive. In addition, complexes of these metals can be toxic. Accordingly, a vast body of recent research has focused on the use of “cheap metals for noble tasks.”1 One particularly attractive target is iron,2 since it is the second-most abundant metal (after aluminum) in the Earth’s crust.3 Moreover, iron is present in a number of metalloproteins and complexes of iron are relatively nontoxic. The availability of multiple oxidation states makes iron even more lucrative for
redox transformations.