Çigˇdem Albayrak

2-[[tris(hydroxymethyl)methyl]aminomethylene]cyclohexa-3,5-dien-1(2H)-one and its 6-hydroxy and 6-methoxy derivatives.

The title compounds, 2-[[tris(hydroxymethyl)methyl]aminomethylene]cyclohexa-3,5-dien-1(2H)-one, C(11)H(15)NO(4), (I), 6-hydroxy-2-[[tris(hydroxymethyl)methyl]aminomethylene]cyclohexa-3,5-dien-1(2H)-one, C(11)H(15)NO(5), (II), and 6-methoxy-2-[[tris(hydroxymethyl)methyl]aminomethylene]cyclohexa-3,5-dien-1(2H)-one, C(12)H(17)NO(5), (III), adopt the keto-amine tautomeric form, with the formal hydroxy H atom located on the N atom, and the NH group and oxo O atom display a strong intramolecular N-H.O hydrogen bond. The N-H...O hydrogen-bonded rings are almost planar and coupled with the cyclohexadiene rings. The carbonyl O atoms accept two other H atoms from the alcohol groups of adjacent molecules in (I), and one from the alcohol and one from the phenol group in (II), but from only one alcohol H atom in (III).

5-(2-Chlorophenyldiazenyl)salicylaldehyde and 4-(2-chlorophenyldiazenyl)-2-[[tris(hydroxymethyl)methyl]aminomethylene]cyclohexa-3,5-dien-1(2H)-one.

The molecule of the former title compound, C(13)H(9)ClN(2)O(2), (I), is nearly planar, with an intramolecular O...O hydrogen bond of 2.692 (2) A. The latter title compound, C(17)H(18)ClN(3)O(4), (II), exists in the keto-amine tautomeric form, with a strong intramolecular hydrogen bond of 2.640 (2) A between the O and N atoms, the H atom being bonded to the N atom. The azobenzene moieties of both molecules have trans configurations, and the dihedral angle between the planes of the two aromatic rings is 4.1 (1) degrees in (I) and 9.9 (1) degrees in (II). The N-H...O hydrogen-bonded rings are almost planar and coupled with the cyclohexadiene rings in (II).

2‐(3‐Methoxy­salicylideneamino)‐1H‐benzimidazole monohydrate

The molecule of the title compound, C15H13O2N3·H2O, is nearly planar, with an intramolecular N⋯O hydrogen bond of 2.616 (2) A. It exists in the phenol–imine form and the dihedral angle between the two aromatic ring systems is 1.04 (5)°. An unsolvated form, crystallized from the same medium, has also been reported [Odabąsogˇlu, Albayrak & Buyukgungor (2005). Acta Cryst. E61, o425–o426].

2-(3-Methoxy­salicylideneamino)-1H-benzimidazole

The molecule of the title compound, C15H13O2N3, deviates slightly from planarity. There is a strong intramolecular N⋯O hydrogen bond of 2.5831 (19) A. The molecule exists in the phenol–imine form and the dihedral angle between the two aromatic ring systems is 14.61 (5)°.

4-[(3-Chloro­phenyl)­diazenyl]-6-methoxy-2-{[tris­(hydroxy­methyl)­methyl]­aminomethyl­ene}cyclo­hexa-3,5-dien-1(2H)-one

Department of Physics, Faculty of Arts and Sciences, Ondokuz Mayõs University, 55139 Kurupelit Samsun, Turkey, Department of Chemistry, Faculty of Arts and Sciences, Ondokuz Mayõs University, 55139 Kurupelit Samsun, Turkey, and Institut fuÈ r Anorganische und Analytische Chemie, Technische UniversitaÈt Braunschweig, Postfach 3329, 38023 Braunschweig, Germany Correspondence e-mail: ccersan@omu.edu.tr

3-Methoxy-5-(4-methylphenyldiazenyl)salicylaldehyde and 3-methoxy-5-(2-methylphenyldiazenyl)salicylaldehyde

The two title molecules, both C(15)H(14)N(2)O(3), are roughly planar and display a trans conformation with respect to the -N=N- double bond, as found for other diazene derivatives. In both compounds, there are intramolecular O-H.O hydrogen bonds and the crystal packing is governed by weak intermolecular C-H.O hydrogen bonds and pi-pi stacking.