Cooperative dihydrogen activation at a Na(I) 2 /Mg(I) 2 ensemble.

[{SiN Dipp }MgNa] 2 ({SiN Dipp } = {CH 2 SiMe 2 N(Dipp)} 2 ; Dipp = 2,6-i-Pr 2 C 6 H 3 ) reacts directly with H 2 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 2 and the tetrametallic core of [{SiN Dipp }MgNa] 2 .