Strong cooperative effects between π-hole and dihydrogen bonds interactions: a computational study

Abstract

The aim of this work is to study cooperative effects between the π -hole and dihydrogen bond (DHB) interactions in the ternary X 3 BNCHHM complexes, where X = H, F and M = Li, Na, BeH, BeF, BeCH 3 , MgH, MgF, MgCH 3 . The properties of the resulting complexes are studied by molecular electrostatic potential, non-covalent interaction index and natural bond orbital analyses. It is found that there is a substantial shortening of HH bond distances in the X 3 BNCHHM complexes, especially in M = Li and Na. Such remarkable variation in the HH binding distances has not been reported for the DHB interactions previously. The formation of a HH interaction in the H 3 BNCHHM and F 3 BNCHHM complexes makes an increase in the interaction energy of BN bonds by 3%-22% and 9%-320%, respectively. The cooperative effects in the ternary complexes make a sizable increase in the 15 N chemical shielding and total spin-spin coupling constants across the BN bonding, which can be regarded as an evidence for the reinforcement of π -hole interactions in the ternary complexes with respect to the corresponding binary systems.

The Key Role of Orbital Interaction in Cooperativity between B⋅⋅⋅N and Hydrogen/Lithium Bonding: An ab initio Study

“…The interaction energies of the binary and ternary complexes are given in Table . The B⋅⋅⋅N interaction energies in the binary complexes are between −5.70 kcal/mol in F 3 B⋅⋅⋅NCH and −66.49 kcal/mol in C 5 H 5 B⋅⋅⋅NCLi, which are in good agreement with the energy range of B⋅⋅⋅N interactions in literature ,,. For example, the calculated interaction energy of the F 3 B⋅⋅⋅NCH complex in the present study (‐5.70 kcal/mol) is close to that reported by Graboweski (‐5.20 kcal/mol) at the MP2/aug‐cc‐pVTZ level .…”

Can we quantitatively evaluate the mutual impacts of intramolecular metal–ligand bonds the same as intermolecular noncovalent bonds?

“…1 There are some well-known methodologies for the evaluation of the cooperativity of noncovalent bonds and the calculation of related cooperative energies. The following equations have been frequently used for the evaluation of the cooperativity of coinage-metal bonds with other types of interactions 2–13 and also that of intermolecular noncovalent bonds, especially those including hydrogen bonds, 14–25 dihydrogen bonds, 26–28 beryllium bonds, 29,30 lithium bonds, 31–34 lithium–π, 35 halogen bonds, 36–48 chalcogen bonds, 49–51 pnicogen bonds, 52–56 cation–π interactions, 57–60 anion–π interactions, 61–63 π⋯π interactions, 64 σ -hole 65,66 and π -hole 67–70 interactions in ternary systems. Δ ABC = IE total ABC − (IE ABC A–B + IE ABC B–C + IE ABC A–C ) E coop = SE ABC − (SE AB + SE BC + SE ABC AC ) E coop = SE ABC − (SE AB + SE BC )In the above equations, Δ ABC and E coop correspond to the three-body term 71–77 and cooperative energy, respectively. The term IE total ABC is used for the value of the total interaction energy of the ABC system, and the terms IE ABC AB , IE ABC BC and IE ABC AC are used for pairwise interaction energies in the structure of the ABC system.…”