ScotCHEM lecture -Dihydrogen and Polyfunctional Ligands: Coordination Chemistry and Catalysis

More than 30 years ago, the proof by neutron diffraction that dihydrogen could be coordinated to a metal center without H-H bond breaking was published by Gregory Kubas and collaborators. The sigma dihydrogen complexes were born. Nearly at the same time, the concept of agostic interactions was established by Maurice Brookhart and Malcolm Green. Since then, many new complexes displaying agostic interactions or sigma coordination modes have been prepared, and applications in energy and catalysis have emerged. If we want to control activity and selectivity issues, it is necessary to gain knowledge on the properties of this unique class of complexes which involves one (or in some cases two) three-centers, two-electron bonds. In this context, this lecture will provide a few answers to the following points. How far can we define the hydrogen interaction with the metal center? Nowadays, we have access to a large variety of characterization techniques. Some of them might require sophisticated levels and be cost or/and time expensive. Can we bypass them? How can we combine catalytic in situ monitoring, stoichiometric experiments, and various techniques to decipher the mechanism of a complex catalytic system?