Synthesis, crystal structure and Hirshfeld surface analysis of 1-[3-(2-oxo-3-phenyl-1,2-di-hydro-quinoxalin-1-yl)prop-yl]-3-phenyl-1,2-di-hydro-quinoxalin-2-one.

In the title compound, C31H24N4O2, the di-hydro-quinoxaline units are both essentially planar with the dihedral angle between their mean planes being 64.82 (4)°. The attached phenyl rings differ significantly in their rotational orientations with respect to the di-hydro-quinoxaline planes. In the crystal, one set of C-H⋯O hydrogen bonds form chains along the b-axis direction, which are connected in pairs by a second set of C-H⋯O hydrogen bonds. Two sets of π-stacking inter-actions and C-H⋯π(ring) inter-actions join the double chains into the final three-dimensional structure.

Synthesis, crystal structure and Hirshfeld surface analysis of 2-[(4-hy-droxy-phen-yl)amino]-5,5-diphenyl-1H-imidazol-4(5H)-one.

In the title mol-ecule, C21H17N3O2, the five-membered ring is slightly ruffled and dihedral angles between the pendant six-membered rings and the central, five-membered ring vary between 50.78 (4) and 86.78 (10)°. The exocyclic nitro-gen lone pair is involved in conjugated π bonding to the five-membered ring. In the crystal, a layered structure is generated by O-H⋯N and N-H⋯O hydrogen bonds plus C-H⋯π(ring) and weak π-stacking inter-actions.

Synthesis, crystal structure and Hirshfeld surface analysis of 2-phenyl-3-(prop-2-yn-1-yl-oxy)quin-oxaline.

In the title compound, C17H12N2O, the quinoxaline moiety shows deviations of 0.0288 (7) to -0.0370 (7) Šfrom the mean plane (r.m.s. deviation of fitted atoms = 0.0223 Å). In the crystal, corrugated layers two mol-ecules thick are formed by C-H⋯N hydrogen bonds and π-stacking inter-actions.

Crystal structure and Hirshfeld surface analysis of 3-phenyl-1-{3-[(3-phenyl-quinoxalin-2-yl)-oxy]prop-yl}-1,2-di-hydro-quinoxalin-2-one.

In the title compound, C31H24N4O2, the quinoxaline units are distinctly non-planar and twisted end-to-end. In the crystal, C-H⋯O and C-H⋯N hydrogen bonds link the mol-ecules into chains extending along the a-axis direction. The chains are linked through π-stacking inter-actions between inversion-related quinoxaline moieties.

2-[4-(2-Chloro-benz-yl)-3-methyl-6-oxo-1,6-di-hydro-pyridazin-1-yl]-N-(4-fluoro-phen-yl)acetamide.

The conformation of the title mol-ecule, C20H17ClFN3O2, is partly determined by an intra-molecular C-H⋯O hydrogen bond, which leads to a dihedral angle of 14.7 (4)° between the fluoro-benzene ring and the acetamide group. The 2-chloro-benzyl group is rotationally disordered over two orientations in a 0.656 (2): 0.344 (2) ratio. In the crystal, a layered structure is formed by N-H⋯O, C-H⋯O and C-H⋯F hydrogen bonds plus slipped π-π stacking inter-actions.

Diethyl 2,2'-[({2-chloro-5-[(2-eth-oxy-2-oxoeth-yl)(2-methyl-indolin-1-yl)carbamo-yl]phen-yl}sulfon-yl)aza-nedi-yl]di-acetate.

The majority of the title mol-ecule, C28H34ClN3O9S, is disordered over two closely spaced sets of sites; the site occupancy of the major component = 0.542 (3). The conformation of each component is approximately U-shaped with the chloro-benzene ring forming the base and the indolinyl and sulfamoyl groups the sides; an intra-molecular C-H⋯Cl hydrogen bond possibly contributes to the stabilization of the conformation. In the crystal, a corrugated layer structure parallel to the ab plane is formed by C-H⋯O and C-H⋯Cl hydrogen bonds together with C-H⋯π(ring) inter-actions.

5,6,7,8-Tetra-hydro-[1,2,4]triazolo[5,1-b]quinazolin-9(4H)-one.

The triazole ring in the title mol-ecule, C9H10N4O, is not quite coplanar with the six-membered ring to which it is fused, the dihedral angle between the two least-squares planes being 2.52 (6)°. In the crystal, a layered structure is formed by N-H⋯N and C-H⋯O hydrogen bonds plus slipped π-stacking inter-actions, with the fused cyclo-hexene rings projecting to either side.

2-(3-Methyl-2-oxoquinoxalin-1-yl)-N-(4-methyl-phen-yl)acetamide.

The quinoxaline moiety in the title mol-ecule, C18H17N3O2, is not quite planar and the p-tolyl group is rotationally disordered over two nearly equally populated sets of sites. In the crystal, N-H⋯O and C-H⋯O hydro-gen bonds form chains extending along the b-axis direction. Due to the disorder of the p-tolyl rings, short C⋯C distances are observed between adjacent chains.

N-(4-Methoxy-2-nitrophenyl)-2-(3-methyl-2-oxo-1,2-dihydroquinoxalin-1-yl)acetamide.

The quinoxaline unit in the title mol-ecule, C18H16N4O5, is slightly puckered [dihedral angle between the rings = 2.07 (12)°] while the whole mol-ecule adopts an L-shaped conformation. Intra-molecular hydrogen bonding determines the orientation of the substituted phenyl ring and the amide nitro-gen atom is almost planar. The packing in the crystal is governed by C-H⋯O hydrogen bonds and slipped π-stacking inter-actions.

3-Methyl-2-(methyl-sulfan-yl)-5,5-diphenyl-3,5-di-hydro-4H-imidazol-4-one.

In the title mol-ecule, C17H16N2OS, the di-hydro-imidazolone ring is slightly puckered and the methyl-sulfanyl group is nearly coplanar with it. In the crystal, two sets of C-H⋯O hydrogen bonds form corrugated layers of mol-ecules parallel to the ac plane. The layers pack with normal van der Waals contacts between them.

15,15-Diphenyl-2,3,4,5,6,8,9,11,12-octa-hydro-imidazo[2,1-h][1,4,12]trioxa[7]thia-[9]azacyclo-tetra-decin-14(15H)-one.

The title mol-ecule, C23H26N2O4S, adopts a cup-shaped conformation. In the crystal, layers lying parallel to the ab plane are formed by C-H⋯O hydrogen bonds and C-H⋯π(ring) inter-actions. The layers stack along the c-axis direction through normal van der Waals inter-actions.

3-(2-Bromo-eth-yl)-5,5-di-phenyl-imidazolidine-2,4-dione.

The imidazolidine ring in the title mol-ecule, C17H15BrN2O2, is slightly ruffled [r.m.s. deviation = 0.0192 Å], while the attached phenyl rings at the C atom at the position between the amine and carbonyl centres are rotated well out of its mean plane [dihedral angles with the imidazolidine ring = 63.60 (8) and 76.4 (1)°]. In the crystal, a three-dimensional network features N-H⋯O and C-H⋯O hydrogen bonds together with C-H⋯π(ring) inter-actions.

Crystal structure of ethyl 2-{4-[(2-oxo-3-phenyl-1,2-di-hydro-quinoxalin-1-yl)meth-yl]-1H-1,2,3-triazol-1-yl}acetate.

The quinoxaline portion of the title mol-ecule, C21H19N5O3, is not quite planar as indicated by a dihedral angle of 3.38 (7)° between the constituent rings. The mol-ecule is 'U-shaped', which is consolidated by an intra-molecular anti-parallel carbonyl electrostatic inter-action with C··O distances of 2.8905 (16) and 3.0221 (15) Å, in the crystal forms corrugated layers through C-H⋯O and C-H⋯N hydrogen bonds and C-H⋯π(ring) and π-stacking inter-actions.

2-Azido-N-(4-methyl-phen-yl)acetamide.

The asymmetric unit of the title compound, C9H10N4O, comprises three independent mol-ecules, two pairs of which differ significantly in the rotational orientation of the azido group and one pair having very similar conformations; the N-N-C-C torsion angles are -173.9 (2), -102.7 (2) and -173.6 (2)°. In the crystal, each independent mol-ecule forms N-H⋯O hydrogen bonds with its glide-plane-related counterparts, forming zigzag chains extending along the c-axis direction.

Ethyl 2-[4-(4-meth-oxy-benz-yl)-3-methyl-6-oxopyridazin-1-yl]acetate.

In the title mol-ecule, C17H20N2O4, the inner part of the ester substituent is nearly perpendicular to the di-hydro-pyridazine ring, forming a dihedral angle of 83.21 (7)°. In the crystal, inversion dimers are formed by pairwise C-H⋯O inter-actions with the dimers connected into chains extending along the b-axis direction by C-H⋯π(ring) inter-actions. The chains are connected by π-stacking inter-actions to give corrugated layers parallel to the ab plane. The terminal ethyl group is disordered over two two sets of sites with the major component having a site occupancy factor of 0.715 (10).

3-Isobutyl-5,5-di-phenyl-imidazolidine-2,4-dione.

The imidazolidine ring in the title mol-ecule, C19H20N2O2, is slightly 'ruffled'. In the crystal, a layer structure is generated by N-H⋯O and C-H⋯O hydrogen bonds plus C-H⋯π(ring) inter-actions.

Crystal structure and Hirshfeld surface analysis of N-(2,6-di-methyl-phen-yl)-2-[3-hy-droxy-2-oxo-3-(2-oxoprop-yl)indolin-1-yl]acetamide.

The cup-shaped conformation of the title mol-ecule, C21H22N2O4, is largely determined by an intra-molecular N-H⋯O hydrogen bond. In the crystal, double layers of mol-ecules are formed by O-H⋯O and C-H⋯O hydrogen bonds. A Hirshfeld surface analysis was performed, which confirms the regions that are active for inter-molecular inter-actions.

Crystal structure and Hirshfeld surface analysis of 2-azido-N-(4-fluoro-phen-yl)acetamide.

The asymmetric unit of the title compound, C8H7FN4O, consists of two independent mol-ecules differing in the orientation of the azido group. Each mol-ecule forms N-H⋯O hydrogen-bonded chains along along the c-axis direction with its symmetry-related counterparts and the chains are connected by C-F⋯π(ring), C=O⋯π(ring) and slipped π-stacking inter-actions. A Hirshfeld surface analysis of these inter-actions was performed.

Crystal structure and Hirshfeld surface analysis of 2-chloro-N-(4-meth-oxy-phen-yl)acetamide.

In the title mol-ecule, C9H10ClNO2, the meth-oxy group lies very close to the plane of the phenyl ring while the acetamido group is twisted out of this plane by 28.87 (5)°. In the crystal, a three-dimensional structure is generated by N-H⋯O, C-H⋯O and C-H⋯Cl hydrogen bonds plus C-H⋯π(ring) inter-actions. A Hirshfeld surface analysis of the inter-molecular inter-actions was performed and indicated that C⋯H/H⋯C inter-actions make the largest contribution to the surface area (33.4%).

5-(Pyridin-4-ylmeth-yl)-1H-pyrazolo-[3,4-d]pyrimidin-4(5H)-one.

In the title compound, C(11)H(9)N(5)O, the pyrazolo-pyrimidin-4-one ring system is almost planar, with a maximum deviation of 0.0546 (13) Šfor the O atom. The crystal packing is stabilized by inter-molecular N-H⋯N, C-H⋯O and C-H⋯N hydrogen bonds. In addition, π-π stacking is found between the pyridine ring and the pyrazolo-pyrimidin-4-one ring systems, with centroid-centroid distances in the range 3.9627 (12)-4.6781 (12) Å.