π‐Hole Bonds: Boron and Aluminum Lewis Acid Centers

Abstract

MP2/aug-cc-pVTZ calculations were performed on complexes of boron and aluminum trihydrides and trihalides with hydrogen cyanide (ZH3 -NCH and ZX3 -NCH; Z=B, Al; X=F, Cl). The complexes are linked through the B⋅⋅⋅N and Al⋅⋅⋅N interactions, which are named as triel bonds and which are classified as π-hole bonds. It was found that they possess numerous characteristics of typical covalent bonds, since they are ruled mainly by processes of the electron charge shift from the Lewis base to the Lewis acid unit. Other configurations of the ZH3 -NCH and ZX3 -NCH complexes linked by the dihydrogen, hydrogen, and halogen bonds were found. However, these interactions are much weaker than the corresponding π-hole bonds. The quantum theory of atoms in molecules and the natural bond orbital approaches were applied to characterize the complexes and interactions analyzed. The crystal structures of triel trihydrides and triel trihalides were also analyzed for comparison with the results of calculations.

Regioselectivity of the interaction of temozolomide with borane and boron trifluoride

“…Water's first choice of O17 as a binding site does mirror the two Lewis acids where this site is clearly one of the preferred locations. Lastly, very recent work [30] confirms the considerably stronger interactions of BH 3 as compared to BF 3 when interacting with a Lewis base. …”

Abnormal synergistic effects between Lewis acid–base interaction and halogen bond in F3B···NCX···NCM

“…Very recently, Grabowski performed a detailed analysis for the complexes of triel trifluorides with hydrogen cyanide and named these interactions as triel bonds [24,25]. Complexes F 3 B···NCX···NCM have C 3v symmetry, and BF 3 molecule exhibits a significant change in geometry from a planar structure in the monomer to an umbrella one in the complex ( Figure 1).…”

“…Our finding is a new supplement for the cooperative effect among different types of intermolecular interactions, and the phenomenon of the abnormal synergistic enhancement will play a significant role in the field of molecular recognition. Importantly, lots of crystal structures formed by F 3 B through triel bonds have been searched in the Cambridge Structural Database [24].…”

Two faces of triel bonds in boron trihalide complexes

“…Hence, boron often interacts strongly with Lewis bases complementing the octet structure by their electrons . These are triel bonds that are defined as interactions where the element of the 13th group plays a role of the Lewis acid center …”