The bio-organometallic chemistry of active site iron in hydrogenases

The recent X-ray crystal structure determinations of several hydrogenase enzymes have engaged the organometallic community owing to the presence of CN- and CO ligands bound to iron in the active sites. This review focuses primarily on the structural features of these metalloproteins and discusses synthetic efforts to develop small molecule models of the active sites. Specific attention is given to the use of infrared spectroscopy as an additional tool to probe different enzyme states. In addition, structurally dissimilar complexes which show some ability to facilitate either dihydrogen uptake or production, are reviewed as possible functional models. Insights from earlier work with metal hydride chemistry and recent theoretical studies are discussed in terms of functional mechanistic proposals. (C) 2000 Elsevier Science S.A. All rights reserved.