Renewable energy and sustainable fertilizer production are closely connected to small molecule activation. Such processes are accomplished in Nature, for instance, by the photosystem, hydrogenase enzymes and nitrogenase. Especially the homogeneous reduction of molecular nitrogen under ambient conditions turned out to be a hard problem and has become a holy grail in inorganic chemistry and homogeneous catalysis. The theoretical study of these processes is feasible with the tools provided by quantum chemistry. Clearly, accuracy of contemporary quantum chemical approaches is still an issue, but new challenges arise as the reduction of small molecules bound to a transition metal fragment turns out to produce a combinatorial problem. If the transferred hydrogen species are produced by strong acids and reductants, numerous structures need to be considered for a complete description of a catalytic cycle that may eventually form ammonia. The number and order of transferred protons and electrons as well as the spin state of the metal complexes produced are a priori unknown. All combinations need to be investigated if experimental data does not rule out some of them. Hydrogenation of the ligand environment of the metal fragment also requires special attention for predictive theoretical investigations as this can lead to decomposition reactions. This talk elaborates on potential obstacles and cures at the examples of homogeneous dinitrogen reduction and also for the oxygen inhibition of [FeFe] hydrogenases.

How predictive is quantum chemistry for small molecule activation? Catalytic dinitrogen fixation and the degradation of [FeFe] hydrogenase by oxygen

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.