The Influence Of Monomer Deformation On Triel And Tetrel Bonds Between Trr3/Tr4 (Tr = Al, Ga, In; T = Si, Ge, Sn) And N-Base (N-Base = Hcn, Nh3, Cn-)

A series of Lewis acid TrF3 and TF4 molecules (Tr = Al, Ga, In and T = Si, Ge, Sn) were allowed to engage in triel and tetrel bonds, respectively, with HCN, NH3, and CN- Lewis base. The interaction energies are quite large, approaching 96 kcal/mol in some cases. The deformation energy of Lewis acid monomer is larger than that of Lewis base monomer. The binding energy, which takes deformation energy into account, is thus significantly lower than the interaction energy, particularly for the complexes containing Al or Sn central atom. The triel and tetrel bonds can still form even if the Lewis acid and Lewis base molecule are not allowed to adjust their internal geometries, but their interaction energies are drastically weakened, dropping by 18% to 90%. The monomer deformation also contributes to the complexation by strengthening its pi/sigma-hole by up to 2.6 times.