Spodium and tetrel bonds involving Zn(II)/Cd(II) and their interplay

Abstract

Ab initio calculations consider SpCO3/SpSO4/SpCl2 (Sp = Zn(II), Cd(II)) as molecules that can engage in both a spodium bond or a tetrel bond through O or Cl. NCH, NHCH2, and NH3 are considered as Lewis bases. The Sp···N spodium bonds are very strong, with interaction energies in the 12–59 kcal/mol range. Those bonds involving Zn are somewhat stronger than Cd, and bond strength diminishes in the SO4 > CO3 ≫ 2Cl ligand order. Tetrel bonds between the Si of SiH3F and a O or Cl atom of the ligand are of moderate strength of 2–9 kcal/mol. In triads in which both a spodium and tetrel bond are simultaneously present, there is a positive cooperativity between them. The bond enhancement is particularly significant in the tetrel bond, whose strength can reach as much as 15 kcal/mol within the trimer.