6-(2-Hydroxyphenyl)-5,6-dihydrobenzimidazolo[1,2-c]quinazolin-12-ium bromide ethanol solvate

In the title compound, C20H16N3O+·Br−·C2H6O, the phenol ring forms dihedral angles of 84.5 (1) and 89.3 (1)° with the benzimidazole system and the quinazoline benzene ring, respectively. The two N—H groups act as donors in hydrogen bonds with the bromide ion as acceptor, leading to infinite eight-membered chains along [100]. According to graph-set theory the descriptor on the binary level is C 2 1(8). O—H⋯O and O—H⋯Br hydrogen bonds also occur.

In the title compound, C 20 H 16 N 3 O + ÁBr À ÁC 2 H 6 O, the phenol ring forms dihedral angles of 84.5 (1) and 89.3 (1) with the benzimidazole system and the quinazoline benzene ring, respectively. The two N-H groups act as donors in hydrogen bonds with the bromide ion as acceptor, leading to infinite eight-membered chains along [100]. According to graph-set theory the descriptor on the binary level is C 2 1 (8). O-HÁ Á ÁO and O-HÁ Á ÁBr hydrogen bonds also occur.

Comment
In the present work the structure of 2-(tetrahydrobenzimidazolium[1,2-c]quinazolin-5-yl)phenol bromide has been determined to explore its suitability as a bidentate ligand for various metal ions. In the structure the quinazoline ring adopts a chair conformation: atoms C8, C13, C14, N1 and N2 are coplanar, with atom C7 from the plane by 0.178 Å (Figure 1).
The orientation of the phenol ring is determined by a hydrogen-bond between the phenolic oxygen atom and the ethanolic oxygen atom. This ring makes dihedral angles of 84.5° and 89.3° with the benzimidazole and phenyl rings respectively. The The molecular packing of the title compound is shown in Figure 2. A feature of the structure is parallel stacking of the 5-membered ring N2-C14-N3-C16-C15 and the 6-membered ring C15-C16-C17-C18-C19-C20. These planes have an interplanar angle of 0.45 (11)° and an interplanar distance of 3.4118 (8) Å.
The two O-H groups and the two N-H groups act as donors in four different hydrogen bonds, three of them with bromide as acceptor and one of them with the ethanolic oxygen atom as acceptor. In terms of graph set analysis (Etter et al., 1990;Bernstein et al., 1995), three extended hydrogen bond patterns may be selected and characterized by graph set descriptors.
8-membered chains along [100] are formed by the two hydrogen bonds of the type N-H···Br (graph set descriptor C 1 2 (8) on the binary level, Figure 3). A 20-membered ring and a 24-membered ring are formed by six hydrogen bonds within two formula units (Figures 4 and 5). The graph set descriptors R 4 6 (20) and R 4 6 (24), respectively, can be assigned on the ternary level.

Experimental
All chemicals used (reagent grade) were commercially available. A mass of 0.0244 g (200 µmol) of 2-aminobenzaldehyde was dissolved in methanol (10 cm 3 ), and 0.0418 g (200 µmol) of 2-(2-aminophenyl)-1-benzimidazole was added with stirring. After the mixture was heated under reflux for 30 min, a mass of 0.096 g (100 µmol) of trans-[ReOBr 3 (PPh 3 ) 2 ] was added, and heating was continued for a further 30 min. After cooling to room temperature, the solution was filtered and left to evaporate slowly at room temperature. After 2 days 0.063 g (72%) of colourless crystals, with the formulation [C 20  The H atoms were positioned geometrically (C-H = 0.98 Å for CH 3 , 0.99 Å for CH 2 , 0.95 Å for CH, 0.84 Å for OH, 0.88 Å for NH) and treated as riding on their parent atoms [U iso (H) = 1.2U eq (C/N) for CH and NH, U iso (H) = 1.5U eq (C/O) for CH 3 and OH]. Fig. 1. The molecular structure of the title compound (anisotropic displacement ellipsoids drawn at the 50% probablility level).