A comparative computational study of novel X–Be–N2–Li and X–Mg–N2–Li species (X = F, Cl, Br)

A computational study predicts a number of unusual Be- and Mg-containing compounds with general formula X–M–N₂–Li (X = F, Cl, Br; M = Be, Mg). Generally, the X–Be–N₂–Li species were found to be energetically stable with respect to the LiX + Be + N₂ fragments and with respect to the LiBeX + N₂ fragments, whereas the Mg-containing species by comparison were found to be unstable. Harmonic vibrational frequencies and various bonding parameters were also computed and found useful in rationalizing the relative stabilities and trends (for varying X) of these unusual compounds. The high stability of X–Be–N₂–Li is thought to be due mainly to strong electrostatic interactions between the constituent atoms and especially the Be atom in its +2 valence state.