Cooperativity between the hydrogen bonding andσ-hole interaction in linear NCX···(NCH)_n=2–5and O₃Z···(NCH)_n=2–5complexes (X = Cl, Br; Z = Ar, Kr): a comparative study

Abstract

Quantum chemical calculations are performed to investigate the cooperativity of hydrogen bonding with halogen or aerogen bonding interactions in linear NCX···(NCH)n=2–5 and O3Z···(NCH)n=2–5 clusters, where X = Cl, Br and Z = Ar, Kr. To understand the cooperativity mechanism in these systems, the corresponding binary NCX···NCH and O3Z···NCH complexes are also considered. The binding distances, interaction energies, and bonding properties of the NCX···(NCH)n=2–5 and O3Z···(NCH)n=2–5 clusters are analyzed in detail. It is found that the cooperative effects in the hydrogen bonding tend to strengthen X···N and Z···N interactions. For both NCX···(NCH)n and O3Z···(NCH)n clusters, a small bond shrinkage is observed from n = 4 to n = 5, which suggests that the cooperativity effects are almost saturated in the larger clusters (n > 5). As the size of the X or Z atom is increased, the magnitude of the cooperative energy in these systems is also increased, which is mainly ascribed to changes in electrostatic potentials and orbital interactions. Our results indicate that the cooperative effects lead to a substantial change in the 14N nuclear quadrupole coupling constants of the NCH molecule.

On the Importance of σ–Hole Interactions in Crystal Structures

“…After our initial theoretical demonstration that Xe(VI) derivatives were able to participate in directional NCIs with electron-rich species such as Lewis bases and anions [126], several experimental and theoretical [129][130][131] studies have supported these initial findings and expanded the field of NgBs. For instance, the X-ray architecture of XeO 3 shown in Figure 23 shows that each molecule is able to form three Xe•••O NgBs with surrounding XeO 3 moieties (see Table 9 for details).…”

Not Only Hydrogen Bonds: Other Noncovalent Interactions

“…Interestingly, the effect of increasing the pressure (up to 50 GPa) on the aerogen interactions in XeO 3 was also analyzed, resulting in O-hopping along the noncovalent Xe-O• • • Xe aerogen bonds, resembling H-hopping commonly observed in hydrogen bonds [254]. Moreover, cooperativity effects in aerogen bonding clusters were studied [255] and the interplay with other interactions, as well [256][257][258][259].…”