Can gallium dimer react effectively with three H2 molecules to form digallane?

Distinct routes of formation of digallane (4) Ga2H4 and digallane (6) Ga2H6 starting with gallium atoms/H2 and gallium dimers/H2 are compared based on the high level ab initio single-reference CCSD(T) and CASSCF based SOCI and hybrid density functional theory calculations of the mechanisms involved. The predicted reaction paths are of relevance to the recent matrix IR studies on the gallium hydrides, notably the extensive one by Wang and Andrews [X. Wang, L. Andrews, J. Phys. Chem. A 107 (2003) 11371] who isolated and assigned the series of mono- and digallium hydrides including the two digallanes.