Abstract

The 1,5-benzodiazepine ring system exhibits a puckered boat-like conformation for all four title compounds [4-(2-hydroxy-phen-yl)-2-phenyl-2,3- dihydro-1H-1,5-benzodiazepine, C21H18N2O, (I), 2-(2,3-dimethoxy-phen-yl)-4-(2- hydroxy-phen-yl)-2,3-dihydro-1H-1,5-benzodiazepine, C23H22N2O3, (II), 2-(3,4-dimeth-oxy-phen-yl)-4-(2-hydroxy-phen-yl)-2,3-dihydro-1H-1, 5-benzodiazepine, C23H22N2O3, (III), and 2-(2,5-dimethoxy-phen-yl)-4-(2-hydroxy- phen-yl)-2,3-dihydro-1H-1,5-benzo-diaze-pine, C23H22N2O3, (IV)]. The stereochemical correlation of the two C6 aromatic groups with respect to the benzodiazepine ring system is pseudo-equatorial-equatorial for compounds (I) (the phenyl group), (II) (the 2,3-dimeth-oxy-phenyl group) and (III) (the 3,4-dimethoxy-phenyl group), while for (IV) (the 2,5-dimethoxy-phenyl group) the system is pseudo-axial-equatorial. An intra-molecular hydrogen bond between the hydroxyl OH group and a benzodiazepine N atom is present for all four compounds and defines a six-membered ring, whose geometry is constant across the series. Although the mol-ecular structures are similar, the supra-molecular packing is different; compounds (I) and (IV) form chains, while (II) forms dimeric units and (III) displays a layered structure. The packing seems to depend on at least two factors: (i) the nature of the atoms defining the hydrogen bond and (ii) the number of inter-molecular inter-actions of the types O - H⋯O, N - H⋯O, N - H⋯π(arene) or C - H⋯π(arene). © International Union of Crystallography 2007.