2-(4-Bromo-phen-yl)-N-(pyrazin-2-yl)acetamide

In the title compound, C12H10BrN3O, the dihedral angle between the mean planes of the 4-bromo-phenyl and pyrazin-2-yl rings is 54.6 (3)°. An intra-molecular C-H⋯O hydrogen bond generates an S(6) graph-set motif. In the crystal, weak N-H⋯N hydrogen bonds link the mol-ecules into chains along [100]. The chains are linked via C-H⋯N and C-H⋯O hydrogen bonds, forming two-dimensional networks lying parallel to the ab plane.

John JP, Butcher RJ, Narayana B, Yathirajan HS, Sarojini BK. 4-Hy-droxy-N-methyl-benzamide

Three independent mol-ecules comprise the asymmetric unit of the title compound, C8H9NO2, in which the dihedral angles between the amide group and the benzene ring are 3.0 (2), 4.0 (3) and 3.3 (9)°. In the crystal, O-H⋯O hydrogen bonds and weak C-H⋯N inter-actions are observed, forming infinite chains along [101].

2-(3,4-Dichloro-phen-yl)-N-(1,3-thia-zol-2-yl)acetamide

In the title compound, C11H8Cl2N2OS, the mean plane of the dichloro-phenyl ring is twisted by 61.8 (1)° from that of the thia-zole ring. In the crystal, mol-ecules are linked via pairs of N-H⋯N hydrogen bonds with an R 2 (2)(8) graph-set motif, forming inversion dimers which stack along the a-axis direction.

(2E)-1-(4-Chloro-phen-yl)-3-(4-nitro-phen-yl)prop-2-en-1-one

In the title compound, C15H10ClNO3, a substituted chalcone, the dihedral angle between the benzene rings is 5.1 (7)°. The nitro group makes a dihedral angle of 12.5 (3)° with the benzene ring to which it is attached. In the crystal, weak C-H⋯O inter-actions link the mol-ecules into a one-dimensional array along [010]. The crystal studied was an inversion twin, with a refined ratio for the twin components of 0.6060 (9):0.3939 (1).

2-(2,4-Di-chloro-phen-yl)-N-(1,3-thia-zol-2-yl)acetamide

In the title compound, C₁₁H₈Cl₂N₂OS, the mean plane of the di­chloro­phenyl ring is twisted by 72.4 (1)° from that of the thia­zole ring. In the crystal, mol­ecules are linked via pairs of N—H⋯N hydrogen bonds with an R₂²(8) graph-set motif and weak C—H⋯O inter­actions, forming inversion dimers which stack along the c-axis direction.

2-(2,6-Dichloro-phen-yl)-N-(1,3-thia-zol-2-yl)acetamide

In the title compound, C₁₁H₈Cl₂N₂OS, the mean plane of the dichloro­phenyl ring is twisted by 79.7 (7)° from that of the thia­zole ring. In the crystal, molecules are linked via pairs of N—H⋯N hydrogen bonds, forming inversion dimers which stack along the a-axis direction.

(Z)-4-[2-(2,4-Dimethyl-phen-yl)hydrazinyl-idene]-3-methyl-pyrazol-5(1H)-one

The mol­ecule of the title compound, C₁₂H₁₄N₄O, is roughly planar, with a dihedral angle of 8.0 (8)° between the benzene and pyrazole rings, and an intra­molecular N—H⋯O hydrogen bond forms an S(6) ring motif. In the crystal, mol­ecules are linked into an inversion dimer by a pair of N—H⋯O hydrogen bonds, which form an R₂²(8) ring motif.

2-(3,4-Dichloro-phen-yl)-N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)acetamide

In the title compound, C₁₉H₁₇Cl₂N₃O₂, there are three mol­ecules (A, B and C) in the asymmetric unit and each differs in the conformation adopted. As a result of steric repulsion, the amide group is rotated with respect to both the dichloro­phenyl and 2,3-dihydro-1H-pyrazol-4-yl rings, making dihedral angles of 44.5 (2) and 56.2 (2)°, respectively in A, 51.1 (2) and 54.1 (2)° in B, and 53.8 (2) and 54.6 (2)° in C. The dihedral angles between the dichloro­phenyl and 2,3-dihydro-1H-pyrazol-4-yl rings are 54.8 (2), 76.2 (2) and 77.5 (2)° in mol­ecules A, B and C, respectively, while the 2,3-dihydro-1H-pyrazol-4-yl and phenyl rings make dihedral angles of 45.3 (2), 51.2 (2) and 42.8 (2)°, respectively. In the crystal, two of the mol­ecules are linked through N—H⋯O hydrogen bonding to an adjoining mol­ecule, forming dimers of the R₂²(10) type, while the third mol­ecule forms such dimers with itself. C—H⋯O inter­actions link the dimers.

(E)-N'-(4-Fluoro-benzyl-idene)-2-(3-methyl-phen-yl)acetohydrazide

In the title compound, C16H15FN2O, the dihedral angles between the benzene rings are74.7(8), 74.1 (1), 74.2 (7) and 74.3 (5)° in the four independent mol-ecules in the asymmetric unit. In the crystal, N-H-O hydrogen bonds involving the hydrazide and acetyl groups, which form R2(2)(18) ring motifs, link the mol-ecules into dimers, which form columns along [010].

N-(4-Bromo-phen-yl)acetamide: a new polymorph

A new polymorph of the title compound, C8H8BrNO, has been determined at 173 K in the space group P21/c. The previous room-temperature structure was reported to crystallize in the ortho-rhom-bic space group Pna21 [Andreetti et al. (1968 ▶). Acta Cryst. B24, 1195-1198]. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds forming chains along [010]. Weak C-H⋯π inter-actions are also present.

6-(3-Chlorophenyl)imidazo[2,1-b][1,3,4]thiadiazole

In the title compound, C₁₀H₈ClN₃S, the dihedral angle between the mean planes of the benzene and imidazo[2,1-b][1,3,4]thia­diazole rings is 6.0 (9)°. In the crystal, mol­ecules are assembled by the formation of centrosymmetric dimers by π-stacking of the thia­diazole and benzene rings of neighboring mol­ecules [centroid–centroid distance = 3.6938 (11) Å] along [010].

2-(2,4-Dichloro-phen-yl)-N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)acetamide

In the crystal structure of the title compound, C19H17Cl2N3O2, the mol-ecules form dimers of the R2(2)(10) type through N-H⋯O hydrogen bonding. As a result of steric repulsion, the amide group is rotated with respect to both the dichloro-phenyl and 2,3-dihydro-1H-pyrazol-4-yl rings, making dihedral angles of 80.70 (13) and 64.82 (12)°, respectively. The dihedral angle between the dichloro-phenyl and 2,3-dihydro-1H-pyrazol-4-yl rings is 48.45 (5)° while that between the 2,3-dihydro-1H-pyrazol-4-yl and phenyl rings is 56.33 (6)°.

A second monoclinic polymorph of 4-[(E)-(4-benzyl-oxybenzyl-idene)amino]-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one

In the title compound, C₂₅H₂₃N₃O₂, the central benzene ring makes dihedral angles of 77.14 (8) and 87.7 (2)° with the terminal benzene rings and an angle of 1.9 (1)° with the pyrazolone ring. The benzene ring and the N atom of the pyrazole ring bearing the phenyl substituent are disordered over two sets of sites with an occupancy ratio of 0.71 (2):0.29 (2). The N atoms of the pyrazole ring have a pyramidal environment, the sums of the valence angles around them being 354.6 (3) and 352.0 (6)/349.5 (15)°. In the crystal, mol­ecules are packed into layers parallel to the ac plane. The other monoclinic polymorphic form was reported recently [Dutkiewicz et al. (2012 ▶). Acta Cryst. E68, o1324].

2-(2,6-Dichloro-phen-yl)-N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)acetamide

In the title compound, C₁₉H₁₇Cl₂N₃O₂, the amide group is planar and, through N—H⋯O hydrogen bonding to an adjoining mol­ecule, forms dimers of the R₂²(10) type. As a result of steric repulsion, the amide group is rotated with respect to both the dichloro­phenyl and 2,3-dihydro-1H-pyrazol-4-yl rings, making dihedral angles of 71.63 (11) and 57.93 (10)°, respectively. The dihedral angle between the dichloro­phenyl and 2,3-dihydro-1H-pyrazol-4-yl rings is 76.60 (10)° while that between the 2,3-dihydro-1H-pyrazol-4-yl and phenyl rings is 49.29 (7)°. The crystal structure also features weak C—H⋯O inter­actions.

2-(4-Methylphenyl)acetohydrazide

In the title compound, C₉H₁₂N₂O, the dihedral angle between the benzene ring and the mean plane of the acetohydrazide group is 88.2 (7)°. In the crystal, N—H⋯O hydrogen bonds and weak C—H⋯O inter­actions link the mol­ecules into infinite ribbons along [001].

2-(2-Nitrophenyl)acetohydrazide

In the title compound, C₈H₉N₃O₃, the dihedral angle between the benzene ring and the acetohydrazide C—C(=O)—N—N plane [maximum deviation = 0.0471 (13) Å] is 87.62 (8)°. The nitro group is twisted by 19.3 (2)° with respect to the benzene ring. In the crystal, N—H⋯O hydrogen bonds link the mol­ecules into a double-column structure along the b axis.

(E)-N'-(4-Meth-oxy-benzyl-idene)-2-m-tolyl-acetohydrazide

In the title mol-ecule, C17H18N2O2, the benzene rings form a dihedral angle of 83.0 (7)°. In the crystal, N-H⋯O hydrogen bonds, in an R(2)2(8) graph-set motif, link mol-ecules into centrocymmetric dimers, and weak C-H⋯π inter-actions further link these dimers into columns in [100].

N'-[(E)-4-Hy-droxy-benzyl-idene]-2-(naph-tha-len-2-yl-oxy)acetohydrazide

The asymmetric unit of the title compound, C₁₉H₁₆N₂O₃, contains two independent mol­ecules in which the dihedral angles between the naphthalene ring system and the benzene ring are 10.0 (1) and 35.3 (1)°. In the crystal, mol­ecules are linked by N—H⋯O and O—H⋯O hydrogen bonds, forming a two-dimensional framework parallel to (001). Weak C—H⋯O and C—H⋯N hydrogen bonds complete a three-dimensional network.

1-(6-Chloro-1,3-benzothiazol-2-yl)-2-[1-(4-methoxyphenyl)ethylidene]hydrazine

The asymmetric unit of the title compound, C₁₆H₁₄ClN₃OS, contains two independent mol­ecules (A and B) linked into dimers via N—H⋯N hydrogen bonds. The 1,3-benzothia­zol-2-yl ring system and the benzene ring form dihedral angles of 17.08 (8) and 8.63 (7)° in mol­ecules A and B, respectively.

N-(2-Bromophenyl)-2-(naphthalen-1-yl)acetamide

In the title compound, C₁₈H₁₄BrNO, the naphthalene ring system [maximum deviation = 0.015 (3) Å] forms a dihedral angle of 67.70 (10)° with the benzene ring. In the crystal, mol­ecules are linked by N—H⋯O hydrogen bonds into C(4) chains propagating in [100]. A C—H⋯O inter­action reinforces the chain connectivity, generating an R₂¹(6) loop.

2-(4-Bromophenyl)-N-(2,6-dimethylphenyl)acetamide

In the title compound, C₁₆H₁₆BrNO, the dihedral angle between the benzene rings is 69.8 (2)°. In the crystal, N—H⋯O hydrogen bonds link the mol­ecules into C(4) chains propagating in [100]. Adjacent mol­ecules in the chains are also linked by C—H⋯O inter­actions which, along with the N—H⋯O hydrogen bonds, generate R₂¹(6) loops.

Ethyl 6-(4-bromo-phen-yl)-4-(4-fluoro-phen-yl)-2-oxocyclo-hex-3-ene-1-carboxyl-ate

There are two independent mol­ecules in the asymmetric unit of the title compound, C₂₁H₁₈BrFO₃, in which the dihedral angles between the fluoro­phenyl and bromo­phenyl groups are 77.0 (1) and 85.8 (1)°. In one of the mol­ecules, two methine C—H groups of the cyclo­hexene ring are disordered over two sets of sites in a 0.53 (2):0.47 (2) ratio. In both mol­ecules, the atoms of the ethyl group were refined as disordered over two sets of sites with occupancies of 0.67 (2):0.33 (2) and 0.63 (4):0.37 (4). The cyclo­hexene rings have slightly distorted sofa conformations in both mol­ecules. In the crystal, C—H⋯O inter­actions link mol­ecules into chains along the b axis.

2-(4-Chloro-phen-yl)-N-(1,3-thia-zol-2-yl)acetamide

In the title compound, C(11)H(9)ClN(2)OS, the thia-zole ring is nearly planar (r.m.s. deviation = 0.003 Å) and forms a dihedral angle of 64.18 (7)° with the bezene ring. In the crystal, inversion dimers linked by pairs of N-H⋯N(t) (t = thia-zole) hydrogen bonds generate R(2) (2)(8) loops.

1-[3-(4-Fluoro-phen-yl)-5-phenyl-4,5-dihydro-1H-pyrazol-1-yl]ethanone

In the title compound, C(17)H(15)FN(2)O, the pyrazoline ring adopts a flattened envelope conformation. The dihedral angle between the fluoro-substituted benzene ring and the phenyl ring is 69.20 (5)°. In the crystal, a pair of C-H⋯O hydrogen bonds link neighbouring mol-ecules, forming an inversion dimer. The crystal structure is further consolidated by C-H⋯π inter-actions and by a π-π inter-action with a centroid-centroid distance of 3.7379 (6) Å.

N-(1,5-Dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-2-[4-(methyl-sulfan-yl)phen-yl]acetamide

In the title compound, C₂₀H₂₁N₃O₂S, the 2,3-dihydro-1H-pyrazole ring is nearly planar (r.m.s. deviation = 0.023 Å) and forms dihedral angles of 16.96 (6) and 38.93 (6)° with the benzene and phenyl rings, respectively. The dihedral angle between the benzene and phenyl rings is 55.54 (6)°. The mol­ecular conformation is consolidated by an intra­molecular C—H⋯O hydrogen bond, which forms an S(6) ring. In the crystal, inversion dimers linked by pairs of N—H⋯O_p (p = pyrazole) hydrogen bonds generate R₂²(10) loops. The dimers are linked by C—H⋯O hydrogen bonds into sheets lying parallel to (100).