ABSTRACT: The asymmetric unit of the title compound, C(11)H(12)N(2)O, contains two independent mol-ecules. In the crystal structure, inter-molecular C-H?O hydrogen bonds link the mol-ecules. There are ?-? contacts between the quinoxaline rings [centroid-centroid distances = 3.446?(2), 3.665?(2), 3.645?(3) and 3.815?(3)?Å]. There also exist C-H?? contacts between the methyl groups and the quinoxaline rings.
Project description:In the mol-ecule of the title compound, C(19)H(17)ClN(2)O(4), the quinoxaline ring system is planar [maximum deviation = 0.013?(3)?Å] and oriented at a dihedral angle of 80.18?(3)° with respect to the benzene ring. In the crystal structure, inter-molecular C-H?N inter-actions link mol-ecules into chains. ?-? contacts between the quinoxaline systems [centroid-centroid distance = 3.654?(1)?Å] may further stabilize the structure.
Project description:The asymmetric unit of the title compound, [ZnCl(2)(C(12)H(12)N(2))], contains two independent mol-ecules. The Zn(II) atoms are four-coordinated in distorted tetra-hedral configurations by two N atoms from 5,5'-dimethyl-2,2'-bipyridine and two terminal Cl atoms. In the crystal structure, inter-molecular C-H?Cl hydrogen bonds link the mol-ecules. There are C-H?? contacts between the methyl groups and the pyridine and five-membered rings containing Zn(II) atoms; ?-? contacts also exist between the pyridine rings [centroid-centroid distances = 3.665?(5) and 3.674?(5)?Å].
Project description:The quinoxaline system in the title hydrate, C(15)H(13)N(3)·H(2)O, is roughly planar, the r.m.s. deviation for the 18 non-H atoms being 0.188?Å; this conformation features a short intra-molecular C-H?N(pyrazine) inter-action. In the crystal, the amine H atom forms an N-H?O hydrogen bond to the water mol-ecule, which in turn forms two O-H?N hydrogen bonds to the pyrazine N atoms of different organic mol-ecules. These inter-actions lead to supra-molecular arrays in the bc plane that are two mol-ecules thick; additional ?-? inter-actions stabilize the layers [ring centroid-centroid distance = 3.5923?(7)?Å]. The layers stack along the a-axis direction via C-H?? contacts.
Project description:The title heterocyclic compound, C(14)H(15)N(3)O(3), is a new synthetic mol-ecule containing oxazolidine and quinoxaline rings. It is built up from two fused six-membered rings linked to a five-membered oxazolidin-2-one ring by a C(2) chain. Both ring systems are essentially planar [maximum deviation = 0.894?(3)?Å, r.m.s. deviation = 0.0043?Å]. The structure is held together by van der Waals forces [electrostatic interactions between dipoles, O?C = 3.002?(2)?Å] between mol-ecules and by weak ?-? stacking between symmetry-related mol-ecules, with an inter-planar distance of 3.579?Å and a centroid-centroid distance of 3.800?(1)?Å. Inter-molecular C-H?O hydrogen bonds are also observed in the crystal structure.
Project description:The title compound, C(27)H(18)N(4)O·2CH(4)O, is a unsymmetrically substituted quinoxaline. An intra-molecular O-H?N hydrogen bond involving the hydr-oxy and imino groups generates an S(6) ring motif. Inter-molecular C-H?O and N-H?O hydrogen bonds form an R(2) (1)(7) ring motif involving a methanol O atom and two H atoms of the imidazole and benzene rings, respectively. The latter links neighbouring mol-ecules into one-dimensional extended chains along the a axis. The two benzene rings are inclined towards each other, as indicated by the dihedral angle of 52.13?(10)°. The phenol ring is almost coplanar with the basic quinoxaline unit, making a dihedral angle of 2.43?(6)°. The short distances between the centroids of the five- and six-membered rings prove the existence of ?-? inter-actions [centroid-centroid distances = 3.5234?(9)-3.7885?(10)?Å]. The crystal structure is stabilized by intra-molecular O-H?N, inter-molecular O-H?O, N-H?O and C-H?O (× 2) hydrogen bonds and weak inter-molecular C-H?? and ?-? inter-actions.
Project description:In the mol-ecule of the title compound, C(12)H(12)N(2)O, the quinoxaline ring is planar with an r.m.s. deviation of 0.007?(15)?Å. The dihedral angle between the quinoxaline and propenyl planes is 82.1?(2)°. The crystal packing is stabilized by offset ?-? stacking between the quinoxaline rings [centroid-centroid distance = 3.8832?(9)?Å].
Project description:In the title compound, C(21)H(15)FOS, the dihedral angles between the mean plane of the benzofuran fragment and the pendant 3-fluoro-phenyl and phenyl rings are 1.76?(5) and 32.29?(5)°, respectively. In the crystal, mol-ecules are linked by a slipped ?-? inter-action between the furan and benzene rings of neighbouring mol-ecules [centroid-centroid distance = 3.665?(2)?Å, inter-planar distance = 3.391?(2)?Å and slippage = 1.390?(2)?Å].
Project description:In the title mol-ecule, C(16)H(11)N(5), the mean planes of the quinoxaline and indazole fragments form a dihedral angle of 10.62?(5)°. In the crystal, weak inter-molecular N-H?N hydrogen bonds link the mol-ecules into zigzag chains extending in the  direction. The crystal packing also exhibits ?-? inter-actions [centroid-centroid distances of 3.7080?(2) and 3.8220?(5)?Å], which form stacks of the mol-ecules parallel to the a axis.
Project description:In the title compound, C(15)H(8)Cl(4)N(2)O, the quinoxaline ring system is almost planar, with a dihedral angle between the benzene and pyrazine rings of 3.1?(2)°. The 2,4-dichloro-phenyl ring is approximately perpendicular to the pyrazine ring, with a dihedral angle of 86.47?(13)° between them. The crystal packing features inter-molecular N-H?O hydrogen bonds and ?-? stacking inter-actions, with centroid-centroid distances in the range 3.699?(3)-4.054?(3)?Å.
Project description:The title compound, C(18)H(8)Cl(4)N(4), exists in a cis configuration with respect to the bridging C=C bond. The two essentially planar quinoxaline ring systems [maximum deviations = 0.012?(1) and 0.022?(1)?Å] are inclined at an angle of 59.84?(3). In the crystal, adjacent mol-ecules are linked into chains propagating along  via inter-molecular C-H?N hydrogen bonds. Weak inter-molecular ?-? [centroid-centroid distance = 3.6029?(7)°] and C-H?? inter-actions are also observed.