3H2

We want to address fundamental issues involving a unique class of complexes, the dihydrogen complexes. Dihydrogen complexes in which dihydrogen is coordinated to a transition metal centre without H-H bond breaking represent an ideal class in terms of binding strength midway between metal hydrides and physisorption. We propose to investigate the following challenging targets: 1) Establish, in the solid state, the properties of complexes bearing one or more H2 ligands, to understand the synergy between H2 and the transition metal for a better control of the hydrogen transfer processes that ideally should be reversible. 2) Explore synthetic strategies to obtain the first complex bearing three dihydrogen ligands, and evaluate the potential of such a high number of dihydrogen coordinated to a metal center. The concept that increasing the number of dihydrogen ligands for a better hydrogen release has to be demonstrated. 3) Evaluate the properties of dihydrogen and poly-dihydrogen complexes as doping agents for attractive metal hydrides. Mechanistic investigations aimed at determining the key interactions for a reversible hydrogen release will be conducted. Thermodynamics and kinetics will be studied by a variety of techniques including calorimetric and thermal analysis, neutron diffraction techniques and DFT calculations. Major breakthroughs are expected from our strategy based on a consortium bringing together teams with complementary and unique expertise. Future applications could be expected in the areas of energy, hydrogen storage, and catalysis.