Comparison of pentavalent with trivalent pnicogen bonding.
DFT calculations are applied to the interactions between a series of MeZXn Lewis acids (Z = Sb, As, P, X = H, F, n = 2,4) and NH3 as universal Lewis base. The trivalent species form classic noncovalent pnicogen bonds that are strengthened by a heavier Z and by electron-withdrawing substituents. The interaction energies...