Noncovalent bond between tetrel π-hole and hydride

The pi-hole above the plane of the X2T ' Y molecule (T ' = Si, Ge, Sn; X = F, Cl, H; Y = O, S) was allowed to interact with the TH hydride of TH(CH3)(3) (T = Si, Ge, Sn). The resulting THMIDLINE HORIZONTAL ELLIPSIST ' tetrel bond is quite strong, with interaction energies exceeding 30 kcal mol(-1). F2T ' O engages in the strongest such bonds, as compared to F2T ' S, Cl2T ' O, or Cl2T ' S. The bond weakens as T ' grows larger as in Si > Ge > Sn, despite the opposite trend in the depth of the pi-hole. The reverse pattern of stronger tetrel bond with larger T is observed for the Lewis base TH(CH3)(3), even though the minimum in the electrostatic potential around the H is nearly independent of T. The THMIDLINE HORIZONTAL ELLIPSIST ' arrangement is nonlinear which can be understood on the basis of the positions of the extrema in the molecular electrostatic potentials of the monomers. The tetrel bond is weakened when H2O forms an OMIDLINE HORIZONTAL ELLIPSIST ' tetrel bond with the second pi-hole of F2T ' O, and strengthened if H2O participates in an OHMIDLINE HORIZONTAL ELLIPSISO H-bond.