• Maintaining the binding to the metal centre with ligands • Supporting heterolytic cleavage of coordinated dihydrogen • Allowing more efficient intramolecular and intermolecular proton transfer. Consequently, metal complexes (such as Co, Ni or Fe) containing diphosphine ligands with amine bases demonstrate a much greater catalytic rate with lower energy required than the thermodynamically determined species for heterolytic fission of H2 thanks to proton relays. Constructing similar systems including heterolytic fission of H2 molecule with the great support from the metal complexes containing Lewis basic sites, again requires much effort to be taken place. Electron transportation and further deprotonation then eventually complete the separation of H2 molecule. 17