Crystal structure of (E)-2-[(4-hy-droxy-benzyl-idene)aza-nium-yl]benzoate.

The title Schiff base, C14H11NO3, crystallizes as a zwitterion (i.e. proton transfer from the carb-oxy-lic acid group to the imine N atom). The dihedral angle between the aromatic rings is 19.59 (6)° and an intra-molecular N-H⋯O hydrogen bond closes an S(6) ring. In the crystal, inversion dimers linked by pairs of O-H⋯O hydrogen bonds generate R 2 (4)(24) loops. The dimers are linked by C-H⋯O inter-actions, generating (211) sheets.

Ethyl 6-(4-cyclo-propyl-1H-1,2,3-triazol-1-yl)pyridine-3-carboxyl-ate.

In the title compound, C13H14N4O2, which has approximate mirror symmetry, the dihedral angles between the triazole ring and the cyclo-propane and pyridine rings are 87.1 (2) and 7.60 (9)°, respectively. In the crystal, inversion dimers linked by pairs of both C-H⋯N and C-H⋯O inter-actions generate R 2 (2)(6) and R 2 (2)(18) loops, respectively. Further C-H⋯N inter-actions form R 2 (2)(10) loops and link the dimers into [110] chains.

6-[(2,4-Di-methyl-anilino)methyl-idene]-2-hy-droxy-cyclo-hexa-2,4-dienone.

In the title compound, C15H15NO2, the dihedral angle between the aromatic rings is 5.86 (6)°, and an intra-molecular N-H⋯O hydrogen bond generates an S(6) motif, which helps to stabilize the enamine-keto tautomer. An intra-molecular O-H⋯O hydrogen bond also occurs. In the crystal, inversion dimers linked by pairs of O-H⋯O hydrogen bonds generate R 2 (2)(10) loops. A C-H⋯O inter-action links the dimers into [010] chains and aromatic π-π stacking [centroid-centroid separation = 3.6131 (9) Å] also occurs.

2-(3-Chloro-benzo-yl)-3-(3,4-di-chloro-phen-yl)-1-(4-ferrocenylphen-yl)guanidine.

In the title compound, [Fe(C5H5)(C25H17Cl3N3O)], the isolated cyclo-penta-dienyl (Cp) ring is disordered over two set of sites in a 0.577 (8):0.423 (8) ratio. The dihedral angle between the other Cp ring and its attached benzene ring is 13.6 (3)°, and that between the benzene ring and the guanidine group is 64.8 (2)°. One of the N-H groups forms both an intra- and an inter-molecular N-H⋯O hydrogen bond; the other N-H group does not form any hydrogen bonds. In the crystal, pairs of the inter-molecular N-H⋯O hydrogen bonds link the mol-ecules into inversion dimers.

Methyl 2,4-dihy-droxy-5-(4-nitro-benzamido)-benzoate.

In the title compound, C(15)H(12)N(2)O(7), the dihedral angle between the aromatic rings is 4.58 (13)° and the nitro group is rotated from its attached ring by 18.07 (17)°. Intra-molecular N-H⋯O and O-H⋯O hydrogen bonds generate S(5) and S(6) rings, respectively. In the crystal, mol-ecules are linked by O-H⋯O hydrogen bonds, generating [001] C(7) chains. The chains are linked by C-H⋯O inter-actions, forming a three-dimensional network, which incorporates R(2) (2)(7) and R(2) (2)(10) loops.

Methyl 2,4-dihy-droxy-5-(2-methyl-propanamido)-benzoate.

In the title compound, C(12)H(15)NO(5), the dihedral angle between the benzene ring and the C atoms of the terminal isopropyl group is 83.48 (16)°. Intra-molecular N-H⋯O and O-H⋯O hydrogen bonds generate S(5) and S(6) rings, respectively. In the crystal, mol-ecules are linked by O-H⋯O hydrogen bonds, generating C(7) chains propagating in [001]. Weak aromatic π-π stacking [centroid-centroid separation = 3.604 (3) Å] is also observed.

4,4,6a,6b,11,12,14b-Heptamethyl-16-oxo-1,2,3,4,4a,5,6,6a,6b,7,8,9,10,11,12,12a,14a,14b-octa-deca-hydro-12b,8a-(epoxy-methano)-picen-3-yl acetate.

The title compound, C32H48O4, which was extracted from the bark of Rhododendron arboreum, consists of five fused rings to which an acetate and seven methyl groups are attached. The A, D and E rings adopt chair conformations, the B ring is in a distorted chair and the C ring is in a half-chair conformation. The five-membered ring formed by the lactone group, which bridges from the A/B to the B/C ring junctions, is an approximate envelope with the C atom of the methyne group as the flap [displacement from the other four atoms = 0.753 (2) Å]. There are no identified directional inter-actions in the crystal structure.

(O-Methyl di-thio-carbonato-κS)tri-phenyl-tin(IV).

In the title compound, [Sn(C6H5)3(C2H3OS2)], the Sn(IV) atom adopts a distorted SnC3S tetra-hedral coordination geometry. A short Sn⋯O contact [2.988 (4) Å] is also present. The phenyl rings are each disordered over two sets of sites with an occupancy ratio of 0.550 (8):0.450 (8). The crystal studied was found to be a racemic twin with a twin component ratio of 0.57 (18):0.43 (18).

N'-[(E)-3-Bromo-benzyl-idene]pyrazine-2-carbohydrazide.

In the title compound, C12H9BrN4O, the dihedral angle between the aromatic rings is 12.16 (12)°. An intra-molecular N-H⋯N hydrogen bond closes an S(5) ring. In the crystal, C-H⋯O hydrogen bonds link the mol-ecules into C(6) chains propagating in [010]. Very weak aromatic π-π stacking [centroid-centroid separations = 3.9189 (15) and 3.9357 (15) Å] is also observed.

N'-[(E)-1-(2-Hy-droxy-phen-yl)ethyl-idene]pyrazine-2-carbohydrazide.

The title compound, C13H12N4O2, crystallized with two independent mol-ecules (A and B) in the asymmetric unit. Mol-ecule B is planar to within 0.044 (3) Šfor all non-H atoms, while mol-ecule A is slightly twisted, with a dihedral angle of 6.29 (4)° between the mean planes of the pyrazine-2-carbohydrazide and 1-(2-hy-droxy-phen-yl)ethanone moieties (r.m.s. deviations = 0.0348 and 0.0428 Å, respectively). S(5) and S(6) ring motifs are formed in both mol-ecules due to the presence of intra-molecular O-H⋯N and N-H⋯N hydrogen bonds. In the crystal, mol-ecules A and B are linked by a C-H⋯O hydrogen bond. They stack along the a-axis direction, forming columns with π-π inter-actions involving inversion-related pyrazine and benzene rings [centroid-centroid distances = 3.5489 (13)-3.8513 (16) Å].

6-Bromo-1-methyl-4-[2-(1-phenyl-ethyl-idene)hydrazinyl-idene]-3,4-dihydro-1H-2λ(6),1-benzothia-zine-2,2-dione.

In the title compound, C(17)H(16)BrN(3)O(2)S, the dihedral angle between the aromatic rings is 1.24 (15)° and the C=N-N=C torsion angle is 167.7 (3)°. The conformation of the thia-zine ring is an envelope, with the S atom displaced by 0.805 (3) Šfrom the mean plane of the other five atoms (r.m.s. deviation = 0.027 Å). In the crystal, C-H⋯O inter-actions link the mol-ecules into C(10) [010] chains. A weak C-H⋯π inter-action is also observed.

3-Chloro-1-methyl-4-[2-(3-phenyl-allyl-idene)hydrazinyl-idene]-3,4-dihydro-1H-2λ(6),1-benzothia-zine-2,2-dione.

In the title compound, C(18)H(16)ClN(3)O(2)S, the dihedral angle between the aromatic rings is 4.81 (2)° and the alkyl chain takes on an extended conformation [N-C-C-C = 179.2 (4)°]. The conformation of the thia-zine ring is an envelope, with the S atom displaced by -0.805 (3) Šfrom the mean plane of the other five atoms (r.m.s. deviation = 0.046 Å). The Cl atom is an axial conformation and is displaced by 1.761 (4) Šfrom the thia-zine ring plane. In the crystal, inversion dimers linked by pairs of C-H⋯O inter-actions generate R(2) (2)(20) loops and further C-H⋯O hydrogen bonds link the dimers into (001) sheets. Weak aromatic π-π stacking inter-actions [centroid-centroid separations = 3.870 (3) and 3.883 (3) Å] are also observed.

1-Ethyl-4-{2-[1-(4-methyl-phen-yl)ethyl-idene]hydrazinyl-idene}-3,4-dihydro-1H-2λ(6),1-benzothia-zine-2,2-dione.

In the title compound, C(19)H(21)N(3)O(2)S, the dihedral angle between the aromatic rings is 6.7 (2)° and the C=N-N=C torsion angle is 178.0 (2)°. The conformation of the thia-zine ring is an envelope, with the S atom displaced by 0.802 (2) Šfrom the mean plane of the other five atoms (r.m.s. deviation = 0.022 Å). In the crystal, mol-ecules are linked by C-H⋯O inter-actions, generating C(5) chains propagating in [010]. A weak C-H⋯π inter-action is also observed.

3-Chloro-4-[2-(4-chloro-benzyl-idene)hydrazinyl-idene]-1-methyl-3,4-dihydro-1H-2λ(6),1-benzothia-zine-2,2-dione.

In the title compound, C16H13Cl2N3O2S, the dihedral angle between the aromatic rings is 6.62 (2)° and the C=N-N=C torsion angle is 176.2 (4)°. The thia-zine ring shows an envelope conformation, with the S atom displaced by 0.633 (6) Šfrom the mean plane of the other five atoms (r.m.s. deviation = 0.037 Å). The Cl atom is an an axial conformation and is displaced by 2.015 (6) Šfrom the thia-zine ring plane. In the crystal, mol-ecules are linked by C-H⋯O inter-actions, generating a three-dimensional network. Very weak aromatic π-π stacking inter-actions [centroid-centroid separations = 3.928 (2) Å] are also observed.

Ethyl 2-[1-(3-methyl-but-yl)-4-phenyl-1H-1,2,3-triazol-5-yl]-2-oxo-acetate.

In the title compound, C17H21N3O3, the non-planar (r.m.s. deviation = 0.212 Å) ethyl (oxo)acetate group is oriented towards the phenyl substituent. The triazole and benzene rings are twisted with respect to each other, making a dihedral angle of 41.69 (6)°. In the crystal, mol-ecules are arranged into centrosymmetric R 2 (2)(10) dimers via pairs of C-H⋯O inter-actions involving the ethyl (oxo)acetate groups. In addition, the triazole rings show π-π stacking inter-actions, with their centroids at a distance of 3.745 (2) Å.

N'-[(E)-4-Bromo-benzyl-idene]pyrazine-2-carbohydrazide.

In the title compound, C12H9BrN4O, the N'-methyl-idene-pyrazine-2-carbohydrazide and 4-bromobenzene groups are oriented at a dihedral angle of 10.57 (7)°. The hydrazide N-H group is involved in intra-molecular N-H⋯N inter-action, which generates an S(5) motif. A short C-H⋯O inter-action is formed between the methyl-idene H atom and the carbonyl O atom. It connects mol-ecules into chains extending along [100]. In addition, mol-ecules are arranged into stacks extending along [010] via π-π inter-actions between pyrazine and benzene rings, with centroid-centroid distances of 3.837 (2) and 3.860 (2) Å.

(Z)-4-(3-Fluoro-phen-yl)-1-(5-nitro-2-oxo-indolin-3-yl-idene)thio-semicarbazide.

In the title compound, C(15)H(10)FN(5)O(3)S, an intra-molecular N-H⋯N hydrogen bond generates an S(5) ring, whereas N-H⋯O and C-H⋯S inter-actions complete S(6) ring motifs. The dihedral angle between the isatin ring system and the fluoro-benzene ring is 5.96 (6)° and the complete mol-ecule is close to planar (r.m.s. deviation for all the non-H atoms = 0.112 Å). In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds to form C(8) chains along the [100] direction and C-H⋯O inter-actions are also observed.

5-(5-Bromo-2-meth-oxy-phen-yl)-2-fluoro-pyridine.

In the title compound, C(12)H(9)BrFNO, the dihedral angle between the aromatic rings is 51.39 (5)°; the C atom of the meth-oxy group is close to being coplanar with its attached ring (r.m.s. deviation = 0.0172 Å] and is oriented away from the pyridine ring. In the crystal, mol-ecules inter-act by van der Waals forces.

N-[4-(4-Nitro-phen-oxy)phen-yl]acetamide.

The asymmetric unit of the title compound, C(14)H(12)N(2)O(4), contains two mol-ecules that differ principally in the orientation of the acetamide substituent to the adjacent benzene ring with dihedral angles of 44.77 (7) and 19.06 (7)°. The dihedral angles between the benzene rings are 64.46 (4) and 80.84 (4)°. In the crystal, classical N-H⋯O hydrogen bonds form C(4) chains along [100]. These chains are inter-linked by C-H⋯O contacts forming R(2) (2)(10) rings. In the crystal, π-π inter-actions are observed with a distance of 3.5976 (18) Šbetween the centroids of the nitro-substituted benzene rings of one type of mol-ecule.

4-[(E)-({4-[(4-Amino-phen-yl)sulfon-yl]phen-yl}imino)-meth-yl]phenol ethanol monosolvate.

In the title compound, C(19)H(16)N(2)O(3)S·C(2)H(6)O, the 4-hy-droxy-benzyl-idene group is oriented at dihedral angles of 73.17 (7) and 77.06 (7)° with respect to the aniline groups. The sulfonyl group make dihedral angles of 44.89 (13) and 59.16 (12)° with the adjacent aniline groups. In the crystal, a two-dimensional polymeric network parallel to (010) is formed by N-H⋯O, O-H⋯N and O-H⋯O hydrogen bonds. There also exist π-π inter-actions with a distance of 3.5976 (18) Šbetween the centroids of hy-droxy-phenyl rings.