Dihydrogen (H₂) chemistry has recently gained major importance in conjunction with the advent of hydrogen technology and its potential application as a future energy carrier. The fuel cell technology has contributed to these developments. Application of certain types of fuel cells has not only become possible by solving many technological problems on the one hand, but also by use of sophisticated hydrogen chemistry. However, various aspects of hydrogen chemistry related to technology remained to be solved, such as with hydrogen storage and appropriate chemical hydrogen transformations. Development of chemical transformations for a second generation approach to build new types of fuel cells, which would allow to avoid noble metal chemistry, needs to be addressed. Circumventing noble metal mediated H₂ chemistry remains a major hurdle for industrial applications.

A conceptually new, basic research approach to hydrogen chemistry has been chosen to solve most if not all of the fundamental chemical problems. Respective chemical transformations comprise of processes involving hydrogenations/dehydrogenations and transfer hydrogenations occurring as 1,2-additions/1,2-eliminations or type II dyotropic rearrangements. Under ambient conditions proper hydrogen reactivity requires support from mediating reaction centres, which normally turn out to be catalytic reaction centres showing repetitive turnovers of the molecules. For decades related research focussed on developments of Wilkinson type transition metal catalyses with the characteristics of oxidative addition of H₂ to the transition metal centres as the prominent H₂ related reaction steps occurring with its formal homolytic splitting. Major drawbacks of this chemistry are however the quite limiting conditions of a “must” to use noble metal catalysts and the strong preference of Wilkinson type catalysts for reactions with mostly relatively unpolar or less polar unsaturated molecules.

These drawbacks are envisaged to be overcome by further developments and utilizations of recently emerged aspects of hydrogenation/dehydrogenation and transfer hydrogenation catalysts splitting the H₂ molecule formally in a heterolytic fashion. Hydrogenations using heterolytic splitting of H₂ are cumulatively denoted as “ionic hydrogenations” and are to the main part also transition metal catalyzed. Only very recently a new type of heterolytic H₂ splitting was discovered with main group element compounds and respective “ionic hydrogenation” chemistry was also found to exist. It is denoted as “metal-free”.  Transfer hydrogenations are also related to “ionic hydrogenations“ operating on the basis of simultaneously occurring double H transfers, but do not involve hydrogen directly. The catalytic potential of these transfer hydrogenations has yet not fully been exploited. In summary this means that comprehensive chemical developments for “ionic hydrogenations” and transfer hydrogenations are lacking and were therefore taken as targets of this project. Still another way to activate the H₂ molecule is its scarcely explored controlled radical interaction with simultaneously acting two metal centres, which eventually might lead to efficient hydrogenation systems, as well. A broad search for new hydrogenation catalyses builds the chemical platform for cooperation within this project.

Taking advantage of synergistic effects and mutual stimulations five organometallic chemistry groups, one physical chemistry group  and one theoretical chemistry group got engaged in this Forschergruppe-project and set out to study the above listed fundamental aspects of hydrogenation chemistry together with their possible utilizations in form of efficient catalyses. Two groups (Erker, Pfaltz) of the Forschergruppe-team will get involved in the exploration and exploitation of a “metal-free” H₂ chemistry using main group elements or organic heteropolar hydrogen splitting systems; two other groups (Rieger, Grützmacher) have planned to get involved in a related “metal-containing” H₂ chemistry utilizing transition metal centres and one group will focus on transfer hydrogenations being related to both main group element and transition metal chemistry (Berke). One group will lay the foundation for exact electronic views of the molecules and chemical transformations appearing in this project by application of accurate theoretical calculations (Grimme).