Boron–π interactions in two 3-(dihydroxyboryl)anilinium salts analyzed by crystallographic studies and supported by the noncovalent interactions (NCI) index theoretical approach

Abstract

In the title compounds, 3-(dihydroxyboryl)anilinium bisulfate monohydrate, C6H9BNO2 +·HSO4 −·H2O (I), and 3-(dihydroxyboryl)anilinium methyl sulfate, C6H9BNO2 +·CH3SO4 − (II), the almost planar boronic acid molecules are linked by pairs of O—H...O hydrogen bonds, forming centrosymmetric motifs that can be described by the graph-set R 2 2(8) motif. In both crystals, the B(OH)2 group acquires a syn–anti conformation (with respect to the H atoms). The presence of the hydrogen-bonding functional groups B(OH)2, NH3 +, HSO4 −, CH3SO4 − and H2O generates three-dimensional hydrogen-bonded networks, in which the bisulfate (HSO4 −) and methyl sulfate (CH3SO4 −) counter-ions act as the central building blocks within the crystal structures. Furthermore, in both structures, the packing is stabilized by weak boron–π interactions, as shown by noncovalent interactions (NCI) index calculations.