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

The aim of this work is to study cooperative effects between the pi-hole and dihydrogen bond (DHB) interactions in the ternary X3B center dot center dot center dot NCH center dot center dot center dot 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 center dot center dot center dot H bond distances in the X3B center dot center dot center dot NCH center dot center dot center dot HM complexes, especially in M = Li and Na. Such remarkable variation in the H center dot center dot center dot H binding distances has not been reported for the DHB interactions previously. The formation of a H center dot center dot center dot H interaction in the H3B center dot center dot center dot NCH center dot center dot center dot HM and F3B center dot center dot center dot NCH center dot center dot center dot HM complexes makes an increase in the interaction energy of B center dot center dot center dot N bonds by 3%-22% and 9%-320%, respectively. The cooperative effects in the ternary complexes make a sizable increase in the N-15 chemical shielding and total spin-spin coupling constants across the B center dot center dot center dot N bonding, which can be regarded as an evidence for the reinforcement of pi-hole interactions in the ternary complexes with respect to the corresponding binary systems. [GRAPHICS] .