Theoretical Analysis of Cooperative Magnesium, Halogen, and Hydrogen Bonds in Complexes Involving MgMe ₂ and HOX (X = F, Cl, Br, I)

MgMe2 can act in a dual capacity, as an electron donor through a methyl group, or as an acceptor via Mg. HOX is also capable of both functions, accepting density at its H and halogen X termini, or donation via the central O. Bonding between these two molecules can therefore encompass either hydrogen, halogen, or Mg-bonds, named according to the identity of the electron acceptor atom. Quantum chemical calculations are used to assess the strengths and other properties of these bonding motifs, which show the MgBs to be strongest, some exceeding 50 kJ/mol, followed by HBs and then by XBs, where the latter is highly influenced by the identity of X. The presence of a MgB enhances the strengths of the others, adding as much as 13 kJ/mol to the total binding energy. In contrast, the HB and XB exert an anticooperative effect on one another. The synergy between the MgB and the other two bonds can be used to build highly stable extended systems, with applications to the design of supramolecular structures.