Revisiting conventional noncovalent interactions towards a complete understanding: from tetrel to pnicogen, chalcogen, and halogen bond

Typical noncovalent interactions, including tetrel (TtB), pnicogen (PniB), chalcogen (ChalB), and halogen bonds (HalB), were systematically re-investigated by modeling the N & ctdot;Z interactions (Z = Si, P, S, Cl) between NH3 - as a nucleophilic, and SiF4, PF3, SF2, and ClF - as electrophilic components, employing highly reliable ab initio methods. The characteristics of N & ctdot;Z interactions when Z goes from Si to Cl, were examined through their changes in stability, vibrational spectroscopy, electron density, and natural orbital analyses. The binding energies of these complexes at CCSD(T)/CBS indicate that NH3 tends to hold tightly most with ClF (-34.7 kJ mol(-1)) and SiF4 (-23.7 kJ mol(-1)) to form N & ctdot;Cl HalB and N & ctdot;Si TtB, respectively. Remarkably, the interaction energies obtained from various approaches imply that the strength of these noncovalent interactions follows the order: N & ctdot;Si TtB > N & ctdot;Cl HalB > N & ctdot;S ChalB > N & ctdot;P PniB, that differs the order of their corresponding complex stability. The conventional N & ctdot;Z noncovalent interactions are characterized by the local vibrational frequencies of 351, 126, 167, and 261 cm(-1) for TtB, PniB, ChalB, and HalB, respectively. The SAPT2+(3)dMP2 calculations demonstrate that the primary force controlling their strength retains the electrostatic term. Accompanied by the stronger strength of N & ctdot;Si TtB and N & ctdot;Cl HalB, the AIM and NBO results state that they are partly covalent in nature with amounts of 18.57% and 27.53%, respectively. Among various analysis approaches, the force constant of the local N & ctdot;Z stretching vibration is shown to be most accurate in describing the noncovalent interactions.

Automated summary

In this study, the noncovalent interactions of tetrel, pnicogen, chalcogen, and halogen bonds were systematically investigated by modeling the interactions between NH3 and SiF4, PF3, SF2, and ClF. The characteristics of these interactions were examined through stability, vibrational spectroscopy, electron density, and natural orbital analyses.