Cooperative dihydrogen activation at a Na(I)/Mg(I) ensemble.

[{SiN}MgNa] ({SiN} = {CHSiMeN(Dipp)}; Dipp = 2,6-i-PrCH) reacts directly with H to provide a heterobimetallic hydride. Although the transformation is complicated by the simultaneous disproportionation of magnesium, computational density functional theory (DFT) studies suggest that this reactivity is initiated by orbitally-constrained and interactions between the frontier MOs of both H and the tetrametallic core of [{SiN}MgNa].