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

Abstract

ABSTRACTThe aim of this work is to study cooperative effects between the π-hole and dihydrogen bond (DHB) interactions in the ternary X3B⋅⋅⋅NCH⋅⋅⋅HM complexes, where X = H, F and M = Li, Na, BeH, BeF, BeCH3, MgH, MgF, MgCH3. 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 H⋅⋅⋅H bond distances in the X3B⋅⋅⋅NCH⋅⋅⋅HM complexes, especially in M = Li and Na. Such remarkable variation in the H⋅⋅⋅H binding distances has not been reported for the DHB interactions previously. The formation of a H⋅⋅⋅H interaction in the H3B⋅⋅⋅NCH⋅⋅⋅HM and F3B⋅⋅⋅NCH⋅⋅⋅HM complexes makes an increase in the interaction energy of B⋅⋅⋅N bonds by 3%–22% and 9%–320%, respectively. The cooperative effects in the ternary complexes make a sizable increase in the 15N chemical shielding and total spin–spin coupling constants across the B⋅⋅⋅N 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.