s2 lone pair-driven formation of a 3-center 4-electron (3c-4e) Mg–B–Mg dative bond in neutral Mg(BH3)Mg

Abstract

We report a three-center four-electron (3c-4e) Mg–B–Mg dative bond in the Mg(BH₃)Mg molecule. This bonding motif, involving the simultaneous donation of two s² lone pairs—each from a different Mg atom—to the BH₃ fragment, is uncommon and supported by NBO analysis and ab initio calculations.