{6,6'-Dimeth-oxy-2,2'-[2,2-dimethyl-propane-1,3-diylbis(nitrilo-methyl-idyne)]diphenolato}nickel(II) 1.78-hydrate

3-{[(E)-(2-Hydroxynaphthalen-1-yl)methylidene]amino}pyridinium per-chlorate

In the title Schiff base salt, C₁₆H₁₃N₂O⁺·ClO₄⁻, the pyridine ring and the naphthalene ring system are approximately co-planar [making a dihedral angle of 6.05 (12)°] and an intra­molecular O—H⋯N hydrogen bond occurs between the hydroxyl and imino groups. In the crystal, the cations and anions are linked by N—H⋯O and weak C—H⋯O hydrogen bonds, forming the supra­molecular layers parallel to (100). The crystal studied was an inversion twin refined with minor component = 0.43 (13).

2-[(5'-Chloro-1,1':3',1''-terphenyl-4'-yl)imino]-acenaphthylen-1(2H)-one

The title compound, C30H18ClNO, is a product of the condensation reaction of acenaphthyl-ene-1,2-dione and 5'-chloro-1,1':3',1''-terphenyl-4'-amine. The acenaphthyl-ene fragment and two terminal phenyl rings are rotated relative to the central benzene ring by 72.2 (3), 43.2 (3) and 41.2 (3)°, respectively. This mol-ecular conformation is supported by weak C-H⋯π inter-actions. In the crystal, mol-ecules form centrosymmetric dimers by the stacking inter-actions between two neighboring acenaphthyl-ene fragments, with an inter-planar distance of 3.365 (3) Å. The dimers are bound to each other by weak C-H⋯N and C-H⋯π inter-actions, forming a three-dimensional framework.

1-{(Z)-[2-Meth-oxy-5-(trifluoro-meth-yl)anilino]methyl-idene}naphthalen-2(1H)-one

The title compound, C₁₉H₁₄F₃NO₂, crystallizes in the keto–amine tautomeric form, with a strong intra­molecular N—H⋯O hydrogen bond. The mol­ecule is almost planar; the dihedral angle between the naphthalene ring system and the benzene ring is 4.60 (7)°. In the crystal, mol­ecules are linked into chains along the c axis by C—H⋯O hydrogen bonds. The F atoms of the trifluoro­methyl group are disordered over two positions with refined site occupancies of 0.668 (9) and 0.332 (9).

(E)-N-[(2-Eth-oxy-naphthalen-1-yl)methyl-idene]-2-ethyl-aniline

In the title compound, C₂₁H₂₁NO, the dihedral angle between the naphthalene ring system and the benzene ring is 64.61 (6)°. The mol­ecular structure is stabilized by an intra­molecular C—H⋯N hydrogen bond.

4-[(2E)-2-(2-Hy-droxy-benzyl-idene)hydrazin-1-yl]benzonitrile

The asymmetric unit of the title Schiff base, C₁₄H₁₁N₃O, contains two independent mol­ecules which have similar conformations. The dihedral angles between the benzene rings are 4.19 (9) and 14.18 (9)° in the two mol­ecules. An intra­molecular O—H⋯N hydrogen bond stabilizes the mol­ecular conformation of each mol­ecules. The crystal packing is dominated by pairs of equivalent N—H⋯N and C—H⋯O hydrogen bonds which arrange the mol­ecules into layers parallel to (-111).

2-Amino-3-[(E)-(2-hy-droxy-3-methyl-benzyl-idene)amino]-but-2-ene-dinitrile

The title compound, C₁₂H₁₀N₄O, is a Schiff base obtained from the condensation of diamino­maleonitrile and 2-hy­droxy-3-methyl­benzaldehyde. The mol­ecule is roughly planar, with an r.m.s. deviation of 0.0354 Å, and adopts the phenol–imine tautomeric form. An intra­molecular O—H⋯N hydrogen bond involving the O—H group and the azomethine N atom generates an S(6) ring. In the crystal, there are two N—H⋯N hydrogen bonds.

Zwitterionic (E)-1-[(4-nitro-phen-yl)iminio-meth-yl]naphthalen-2-olate

The title compound, C(17)H(12)N(2)O(3), was synthesized by the reaction of 2-hy-droxy-1-naphthaldehyde with 4-nitro-benzenamine. These condense to form the Schiff base, which crystallizes in the zwitterionic form. In the structure, the keto-amino tautomer has a fairly short intra-molecular N-H⋯O hydrogen bond between the 2-naphthalenone and amino groups, with electron delocalization. The mol-ecule is essentially planar, with a dihedral angle of 1.96 (3)° between the ring systems. In the crystal, the mol-ecules are linked via inter-molecular C-H⋯O hydrogen bonds, forming a layer parallel to (101).

1-[(E)-(2-Methyl-3-nitrophenyl)iminomethyl]-2-naphthol

The title Schiff base compound, C₁₈H₁₄N₂O₃, has an inter­mediate state between NH and OH tautomers. The mol­ecular structure is stabilized by an O—H⋯N hydrogen bond. The dihedral angle between the naphthalene ring system and the benzene ring is 37.44 (5)°.

N′-(5-Chloro-2-hydroxybenzylidene)-2-methoxybenzohydrazide

The title Schiff base compound, C₁₅H₁₃ClN₂O₃, was prepared by the reaction of equimolar quanti­ties of 5-chloro-2-hy­droxy­benzaldehyde with 2-meth­oxy­benzohydrazide in a methanol solution. The dihedral angle between the two benzene rings is 20.6 (3)°. An intra­molecular O—H⋯N hydrogen bond may influence the mol­ecular conformation. In the crystal structure, mol­ecules form chains along the b direction via inter­molecular N—H⋯O hydrogen bonds which are bifurcated involving an intra­molecular N—H⋯O hydrogen bond.

(E)-1-[(2-Fluoro-phen-yl)imino-meth-yl]-2-naphthol-(Z)-1-[(2-fluoro-phen-yl)amino-methyl-idene]naphthalen-2(1H)-one (0.57/0.43)

The title Schiff base compound, 0.57C(17)H(12)FNO·0.43C(17)H(12)FNO, reveals both the enol (OH) and keto (NH) tautomeric forms with occupancies of 0.57 (6) and 0.43 (6), respectively. The tautomeric forms are stabilized by intra-molecular O-H⋯N (enol) and N-H⋯O (keto) hydrogen bonds. The dihedral angle between the naphthalene ring system and the benzene ring is 32.76 (1)°.

N'-[(2-Hydr-oxy-1-naphth-yl)methyl-idene]-2-nitro-benzohydrazide

In the title Schiff base compound, C₁₈H₁₃N₃O₄, prepared by the reaction of 2-hydr­oxy-1-naphthaldehyde with 2-nitro­benzohydrazide, the dihedral angle between the benzene ring and naphthyl ring system is 23.0 (2)°. There is an intra­molecular O—H⋯N hydrogen bond involving the naphthalene hydr­oxy substituent and a hydrazide N atom. In the crystal structure, symmetry-related mol­ecules are linked through inter­molecular N—H⋯O hydrogen bonds, forming chains propagating in [101].

(E)-2-[(2,4-Dichloro-phen-yl)imino-meth-yl]benzene-1,4-diol monohydrate

The title compound, C(13)H(9)Cl(2)NO(2)·H(2)O, represents a Schiff base which adopts the phenol-imine tautomeric form in the solid state. The mol-ecule is approximately planar (r.m.s. deviation 0.0818 Å), and the dihedral angle between the two aromatic rings is 7.46 (12)°. An O-H⋯N inter-action generates an S(6) ring. In the crystal, mol-ecules are linked by inter-molecular O-H⋯O hydrogen bonds involving the solvent water mol-ecule, forming chains.

2-Bromo-4-chloro-6-(cyclo-pentyl-imino-meth-yl)phenol

All atoms of the title mol-ecule, C(12)H(13)BrClNO, except the C and H atoms of the cyclo-pentane methyl-ene groups lie on a crystallographic mirror plane. The cyclo-pentane ring adopts an envelope conformation and an intra-molecular O-H⋯N hydrogen bond is observed. In the crystal, mol-ecules are stacked along the b axis by π-π inter-actions [centroid-centroid distance = 3.6424 (11) Å].

1-[(2-Anilinoethyl)iminiomethyl]-2-naphtholate

The title Schiff base compound, C₁₉H₁₈N₂O, was prepared by the reaction of equimolar quanti­ties of 2-hydr­oxy-1-naphthaldehyde with N-phenyl­ethane-1,2-diamine in a methanol solution. The mol­ecule adopts a zwitterionic conformation with the naphthyl OH group deprotonated and the imine N atom protonated. An intra­molecular N—H⋯O hydrogen bond forms between them. The dihedral angle between the benzene ring and the naphthyl system is 86.9 (2)°. In the crystal structure, mol­ecules are linked through inter­molecular N—H⋯O hydrogen bonds, forming chains running along the b axis.