1-Benzyl-3-methylquinoxalin-2(1H)-one

The crystal structure of 7-Bromo-2-(4-chloro-phenyl)-quinoxaline, C14H9BrClN2

C14H8BrClN2, monoclinic, P21/n (no. 14), a = 17.1347(11) Å, b = 3.8441(2) Å, c = 18.4127(12) Å, β = 97.861(2)°, V = 1201.40(13) Å3, Z = 4, R gt (F) = 0.0388, wR ref (F 2) = 0.1302, T = 170 K.

Crystal structure and Hirshfeld surface analysis of 2-(2-oxo-3-phenyl-1,2,3,8a-tetra-hydro-quinoxalin-1-yl)ethyl acetate

In the title mol-ecule, C18H16N2O3, the di-hydro-quinoxaline moiety, with the exception of the N atom is essentially planar with the inner part of the methyl-propano-ate group (CH2-CH2-O) nearly perpendicular to it. In the crystal, inversion dimers formed by C-H⋯O hydrogen bonds are connected into oblique stacks by π-stacking and C-H⋯π(ring) inter-actions.

Crystal structure, Hirshfeld surface analysis and DFT study of 1-ethyl-3-phenyl-1,2-di-hydro-quinoxalin-2-one

In the title mol-ecule, C16H14N2O, the di-hydro-quinoxaline moiety is not planar as there is a dihedral angle of 4.51 (5)° between the constituent rings. In the crystal, C-H⋯O hydrogen bonds form helical chains about the crystallographic 21 screw axis in the b-axis direction. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (51.7%), H⋯C/C⋯H (26%) and H⋯O/O⋯H (8.5%) inter-actions. The optimized structure calculated using density functional theory (DFT) at the B3LYP/6-311 G(d,p) level is compared with the experimentally determined structure in the solid state. The calculated HOMO-LUMO energy gap is 3.8918 eV.

Synthesis and crystal structure of (E)-1-benzyl-3-(4-methoxystyryl)quinoxalin-2(1H)-one, C24H20N2O2

C24H20N2O2, monoclinic, P21/c (no. 14), a = 11.1713(3) Å, b = 17.7718(5) Å, c = 10.9852(3) Å, β = 118.990(1)°, V = 1907.67(9) Å3, Z = 4, Rgt(F) = 0.0538, wRref(F2) = 0.1582, T = 296(2) K.

Synthesis and crystal structure of 1-octyl-3-phenylquinoxalin-2(1H)-one, C22H26N2O

C22H26N2O, monoclinic, C2/c (no. 15), a = 47.4887(9) Å, b = 5.0220(1) Å, c = 16.4551(3) Å, β = 108.993(1)°, V = 3710.70(12) Å3, Z = 8, R gt (F) = 0.0345, wR ref(F 2) = 0.0935, T = 150(2) K.

CCDC Nr.: 2025941

Crystal structure and Hirshfeld surface analysis of 1-[(1-butyl-1H-1,2,3-triazol-4-yl)meth-yl]-3-methyl-quinoxalin-2(1H)-one

The title compound, C16H19N5O, is built up from a planar quinoxalinone ring system linked through a methyl-ene bridge to a 1,2,3-triazole ring, which in turn carries an n-butyl substituent. The triazole ring is inclined by 67.09 (4)° to the quinoxalinone ring plane. In the crystal, the mol-ecules form oblique stacks along the a-axis direction through inter-molecular C-HTrz⋯NTrz (Trz = triazole) hydrogen bonds, and offset π-stacking inter-actions between quinoxalinone rings [centroid-centroid distance = 3.9107 (9) Å] and π-π inter-actions, which are associated pairwise by inversion-related C-HDhydqn⋯π(ring) (Dhydqn = di-hydro-quinoxaline) inter-actions. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (52.7%), H⋯N/N⋯H (18.9%) and H⋯C/C⋯H (17.0%) inter-actions.

2-(3-Methyl-2-oxo-1,2-dihydroquinoxalin-1-yl)acetic acid dihydrate

In the title compound, C11H10N2O3·2H2O, the constituent atoms of the dihydroquinoxaline moiety deviate from the mean plane of the unit by +0.0572 (8) to −0.0874 (8) Å while the acetic acid substituent is nearly orthogonal to this plane. The crystal packing consists of corrugated layers constructed by O—H...O, O—H...N and C—H...O hydrogen bonds, which also involve the lattice water molecules. O—H...O hydrogen bonds and π–π stacking interactions hold these layers together.

Ethyl 2-[(2E)-4-decyl-3-oxo-1,2,3,4-tetrahydroquinoxalin-2-ylidene]acetate

In the title compound, C22H32N2O3, the tetrahydroquinoxaline unit is planar. The ester substituent is nearly coplanar with this ring system as a result of an intramolecular N—H...O hydrogen bond. In the crystal, C—H...O hydrogen bonds and π-stacking interactions form oblique stacks which are connected into pairs by additional C—H...O hydrogen bonds. These pairs are further linked into thick sheets, with the n-decyl chains extending out from both surfaces as a result of a third set of C—H...O hydrogen bonds. Intercalation of the n-decyl chains completes the crystal packing.

Ethyl 2-(2-oxo-3-phenyl-1,2-dihydroquinoxalin-1-yl)acetate

In the title compound, C18H16N2O3, the dihydroquinoxaline moiety is planar (r.m.s. deviation = 0.0115 Å) and the majority of the ester substituent is nearly perpendicular to its mean plane. In the crystal, the molecules form oblique stacks along the b-axis direction through slipped π–π stacking interactions between adjacent dihydroquinoxaline units. C—H...O hydrogen bonds between the ester substituents on adjacent stacks form thick layers with the stacks on their outside surfaces. These layers extend along the c-axis direction and are coupled through C—H...π(ring) interactions. The structure was refined as a two-component twin.

Ethyl 2-(3-oxo-1,2,3,4-tetrahydroquinoxalin-2-yl)acetate

In the title compound, C12H14N2O3, the conformation of the ester substituent is partially determined by an intramolecular N—H...O hydrogen bond. The crystal packing consists of layers parallel to (-112) held together by N—H...O and C—H...O hydrogen bonds. The CH/NH portion of the heterocyclic ring is disordered over two sites in a 0.930 (5):0.070 (5) ratio with the disorder also extending to the O atom involved in the intramolecular N—H...O hydrogen bond.