2-Amino-4-nitro-phenol monohydrate.

The title compound, C(6)H(6)N(2)O(3)·H(2)O, crystallizes with two formula units in the asymmetric unit. The mol-ecules are essentially planar with the nitro groups twisted slightly out of the ring planes [maximum deviations from the ring plane of 0.13 (2) and 0.

Theoretical modeling and experimental studies on N-n-decyl-2-oxo-5-nitro-1-benzylidene-methylamine.

The Schiff base compound, N-n-Decyl-2-oxo-5-nitro-1-benzylidene-methylamine, has been -synthesized and characterized by IR, electronic spectroscopy, and X-ray single-crystal determination. Molecular geometry from X-ray experiment of the title compound in the ground state have been compared using the Hartree-Fock (HF) and density functional method (B3LYP) with 6-31G(d) basis set. Calculated results show that density functional theory (DFT) at B3LYP/6-31G(d) level can well reproduce the structure of the title compound.

2-[(4-Chloro-phen-yl)imino-meth-yl]hydro-quinone.

The title compound, C(13)H(10)ClNO(2), exists in the phenol-imine form in the crystal, and the aromatic rings are oriented at a dihedral angle of 2.82 (9)°. An intra-molecular O-H⋯N hydrogen bond results in the formation of a planar six-membered ring.

(E)-4-{2-[(4-Chloro-phen-yl)imino-meth-yl]phen-oxy}phthalonitrile.

In the title compound, C(21)H(12)ClN(3)O, the phenoxy ring makes dihedral angles of 51.42 (5) and 65.01 (6)°, respectively, with the chlorophenyl and phthalonitrile rings.

2-[(E)-(2-Morpholinoeth-yl)iminiometh-yl]-4-nitro-1-oxocyclo-hexa-dienide.

The mol-ecule of the title compound, C(13)H(17)N(3)O(4), exists as a zwitterion, with the H atom of the phenol group being transferred to the imine N atom. The C=O, C(Ar)-C(Ar) and C-N bond lengths are in agreement with the oxocyclo-hexa-dienide-iminium zwitterionic form. A strong intra-molecular N(+)-H⋯O hydrogen bond generates an S(6) ring motif.

3-[(2,4-Dichloro-phen-yl)imino-meth-yl]-2-hydr-oxy-5-methyl-benzaldehyde.

The title compound, C(15)H(11)Cl(2)NO(2), is a Schiff base which adopts the phenol-imine tautomeric form in the solid state, being stabilized by a strong intra-molecular O-H⋯N hydrogen bond. The mol-ecule is almost planar (r.m.

2-[(2,4-Dimethyl-phen-yl)imino-meth-yl]-3,5-dimethoxy-phenol.

X-ray analysis reveals that the title Schiff base compound, C(17)H(19)NO(3), possesses both OH and NH tautomeric character in its mol-ecular structure. The occupancies of the enol and keto tautomers are 0.62 (3) and 0.

2-[(4-Bromo-phen-yl)imino-meth-yl]-3,5-dimethoxy-phenol.

There are two independent mol-ecules in the asymmetric unit of the title compound, C(15)H(14)BrNO(3), with very similar geometrical parameters. Each mol-ecule adopts the phenol-imine tautomeric form, with strong intra-molecular O-H⋯N hydrogen bonds. The two mol-ecules are non-planar, the dihedral angles between the two aromatic rings being are 24.

(E)-2-[(2,4-Dichloro-phen-yl)imino-methyl]-6-methyl-phenol.

The title compound, C(14)H(11)Cl(2)NO, is a Schiff base which adopts the phenol-imine tautomeric form in the solid state. There are two mol-ecules in the asymmetric unit. Head-to-tail π-π inter-actions [centroid-to-centroid distances of 3.

2-[(4-Methoxy-phen-yl)imino-meth-yl]-4-nitro-phenol.

The title Schiff base compound, C(14)H(12)N(2)O(4), is in an inter-mediate state between NH and OH tautomers. Apart from the intra-molecular O-H⋯N hydrogen bond, there are inter-molecular C-H⋯O hydrogen bonds, generating centrosymmetric R(2) (2)(18) and R(2) (2)(14) dimers.

3,5-Dimeth-oxy-2-[(4-propyl-phen-yl)imino-meth-yl]phenol.

The title compound, C(18)H(21)NO(3), crystallizes in the phenol-imine tautomeric form, with the H atom attached to oxygen rather than on nitro-gen. This H atom is involved in a strong intra-molecular O-H⋯N hydrogen bond. A C-H⋯π inter-action is also present.

2-[(4-Ethyl-phen-yl)imino-meth-yl]-3,5-dimethoxy-phenol.

The title compound, C(17)H(19)NO(3), adopts the phenol-imine tautomeric form, with a resonance-assisted O-H⋯N intra-molecular hydrogen bond [O⋯N = 2.551 (3) Å]. The dihedral angle between the two benzene rings is 45.

(E)-4-Methyl-2-{[tris(hydroxymethyl)methyl]iminiomethyl}phenolate.

In the zwitterionic title compound, C(12)H(17)NO(4), an intra-molecular N-H⋯O hydrogen bond generates a six-membered ring, producing an S(6) ring. In the crystal structure, mol-ecules are linked by inter-molecular C-H⋯O and O-H⋯O inter-actions.

2-[(4-Ethoxy-phen-yl)imino-meth-yl]-5-methoxy-phenol.

The title compound, C(16)H(17)NO(3), a Schiff base, is stabilized in the solid state in the phenol-imine tautomeric form, with the H atom located on the hydr-oxy O atom rather than on the N atom. This H atom is involved in a strong intra-molecular O-H⋯N hydrogen bond. The mol-ecule is almost planar, the angle between the benzene rings being 4.

2-[(2,4-Dimethyl-phen-yl)imino-meth-yl]-6-methyl-phenol.

The title compound, C(16)H(17)NO, is a Schiff base which adopts the phenol-imine tautomeric form in the solid state. The mol-ecule is almost planar, with a dihedral angle of 4.61 (4)° between the aromatic rings.

(E)-2-[(2-Chloro-phen-yl)imino-meth-yl]-4-methyl-phenol.

The mol-ecule of the title compound, C(14)H(12)ClNO, adopts the enol-imine tautomeric form, with an intra-molecular O-H⋯N hydrogen bond. In the mol-ecule, the two benzene rings are twisted with respect to each other by 30.6 (2)°.

(E)-4-Bromo-2-[(4-ethyl-phen-yl)imino-meth-yl]phenol.

In the title compound, C(15)H(14)BrNO, the dihedral angle between the two benzene rings is 43.99 (2)°. The mol-ecular conformation is influenced by an intra-molecular O-H⋯N hydrogen bond.