Crystal structure, Hirshfeld surface analysis and energy frameworks of 1-[(E)-2-(2-fluoro-phen-yl)diazan-1-yl-idene]naphthalen-2(1H)-one.

The title compound, C16H11N2OF, is a member of the azo dye family. The dihedral angle subtended by the benzene ring and the naphthalene ring system measures 18.75 (7)°, indicating that the compound is not perfectly planar. An intra-molecular N-H⋯O hydrogen bond occurs between the imino and carbonyl groups. In the crystal, the mol-ecules are linked into inversion dimers by C-H⋯O inter-actions. Aromatic π-π stacking between the naphthalene ring systems lead to the formation of chains along [001]. A Hirshfeld surface analysis was undertaken to investigate and qu-antify the inter-molecular inter-actions. In addition, energy frameworks were used to examine the cooperative effect of these inter-molecular inter-actions across the crystal, showing dispersion energy to be the most influential factor in the crystal organization of the compound.

Synthesis and crystal structure of 2-(1,3-dithietan-2-yl-idene)cyclo-hexane-1,3-dione.

The title compound, C8H8O2S2, contains a cyclo-hexane-1,3-dione ring, which has a twist-boat conformation. The C2S2 ring is close to planar (r.m.s. deviation = 0.023 Å) and the dihedral angle between the mean planes of the cyclo-hexane and 1,3-dithietane rings is 9.1 (3)°. Short intra-molecular S⋯O contacts occur [2.719 (5) and 2.740 (5) Å]. In the crystal, the mol-ecules are linked by weak C-H⋯S hydrogen bonds and short [3.165 (5) Å] S⋯O contacts, forming (010) layers. The prevalence of these inter-actions is illustrated by an analysis of the three-dimensional Hirshfeld surface and by two-dimensional fingerprint plots.

2,6-Di-bromo-4-methyl-aniline.

In the title compound, C7H7Br2N, the C-C-C bond angles of the benzene ring are notably distorted and two short intamolecular N-H⋯Br contacts occur. In the crystal, the mol-ecules are linked by N-H⋯N hydrogen bonds to generate C(2) chains propagating in the [100] direction.

Erratum: Crystal structure and Hirshfeld surface analysis of N-[(2-hy-droxy-naphthalen-1-yl)(3-methyl-phen-yl)meth-yl]acetamide. Corrigendum.

[This corrects the article DOI: 10.1107/S2056989018008423.].

Erratum: Crystal structure and Hirshfeld surface analysis of (Z)-4-(4-hy-droxy-benzyl-idene)-3-methyl-isoxazol-5(4H)-one. Corrigendum.

[This corrects the article DOI: 10.1107/S2056989018007867.].

Calculations of the molecular interactions in 1,3-dibromo-2,4,6-trimethyl-benzene: which methyl groups are quasi-free rotors in the crystal?

Dibromomesitylene (DBMH) is one of the few molecules in which a methyl group is a quasi-free rotor in the crystal state. Density functional theory calculations - using the Born-Oppenheimer approximation (BOa) - indicate that in isolated DBMH, Me4 and Me6 are highly hindered in a 3-fold potential V3 > 55 meV while Me2 symmetrically located between two Br atoms has a small 6-fold rotation hindering potential: V6 ∼ 8 meV. Inelastic neutron scattering studies have shown that this is also true in the crystal, the Me2 tunneling gap being 390 µeV at 4.2 K and V6 ∼ 18 meV. In the monoclinic DBMH crystal, molecules are packed in an anti-ferroelectric manner along the oblique a axis, favoring strong van der Waals interactions, while in the corrugated bc planes each molecule has a quasi hexagonal environment and weaker interactions. This results in the nearby environment of Me2 only being composed of hydrogen atoms. This explains why the Me2 rotation barrier remains small in the crystal and mainly 6-fold. Using the same potentials in the Schrödinger equation for a -CD3 rotor has allowed predicting a tunneling gap of 69 µeV for deuterated Me2 in very good agreement with inelastic neutron scattering measurements. Therefore, because of a rare and unexpected local symmetry in the crystal, the Me2 rotation barrier remains small and 6-fold and hydrogen nuclei are highly delocalized and not relevant to the Born-Oppenheimer approximation. This and the neglect of spin states explain the failure of density functional theory calculations for finding the rotation energy levels of Me2.

Crystal structure and Hirshfeld surface analysis of (Z)-3-methyl-4-(thio-phen-2-yl-methyl-idene)isoxazol-5(4H)-one.

The title compound, C9H7NO2S crystallizes with two independent mol-ecules (A and B) in the asymmetric unit with Z = 8. Both mol-ecules are almost planar with a dihedral angle between the isoxazole and thio-phen rings of 3.67 (2)° in mol-ecule A and 10.00 (1) ° in mol-ecule B. The packing of mol-ecules A and B is of an ABAB⋯ type along the b-axis direction, the configuration about the C=C bond is Z. In the crystal, the presence of C-H⋯O, C-H⋯ N and π-π inter-actions [centroid-centroid distances of 3.701 (2) and 3.766 (2) Å] link the mol-ecules into a three-dimensional architecture. An analysis of Hirshfeld surfaces shows the importance of C-H⋯O and C-H⋯N hydrogen bonds in the packing mechanism of the crystalline structure.

Structural study and Hirshfeld surface analysis of (Z)-4-(2-meth-oxy-benzyl-idene)-3-phenyl-isoxazol-5(4H)-one.

The title compound, C17H13NO3, adopts a Z configuration about the C=C bond. The isoxazole and meth-oxy-benzyl-idene rings are almost coplanar with a dihedral angle of 9.63 (7)° between them. In contrast, the phenyl substituent is twisted significantly out of the plane of the oxazole ring, with the two rings inclined to each other by 46.22 (4)°. The crystal structure features C-H⋯O, C-H⋯N and C-H⋯π hydrogen bonds and π-π contacts. An analysis of the Hirshfeld surfaces points to the importance of H⋯H, H⋯C/C⋯H and H⋯O/O⋯H contacts. The included surface areas of the title compound were compared to those of the isomeric structure (Z)-4-(4-meth-oxy-benzyl-idene)-3-phenyl-isoxazol-5(4H)-one [Zhang et al. (2015 ▸). CrystEngComm, 17, 7316-7322].

Crystal structure and Hirshfeld surface analysis of 2,6-di-iodo-4-nitro-toluene and 2,4,6-tri-bromo-toluene.

The title compounds, 2,6-di-iodo-4-nitro-toluene (DINT, C7H5I2NO2) and 2,4,6-tri-bromo-toluene (TBT, C7H5Br3,), are tris-ubstituted toluene mol-ecules. Both mol-ecules are planar, only the H atoms of the methyl group, and the nitro group in DINT, deviate significantly from the plane of the benzene ring. In the crystals of both compounds, mol-ecules stack in columns up the shortest crystallographic axis, viz. the a axis in DINT and the b axis in TBT. In the crystal of DINT, mol-ecules are linked via short N-O⋯I contacts, forming chains along [100]. In TBT, mol-ecules are linked by C-H⋯Br hydrogen bonds, forming chains along [010]. Hirshfeld surface analysis was used to explore the inter-molecular contacts in the crystals of both DINT and TBT.

Crystal structure and Hirshfeld surface analysis of (2E,2'E)-1,1'-[seleno-bis-(4,1-phenyl-ene)]bis-[3-(4-chloro-phen-yl)prop-2-en-1-one].

In the title com-pound, C30H20Cl2O2Se, the C-Se-C angle is 99.0 (2)°, with the dihedral angle between the planes of the attached benzene rings being 79.1 (3)°. The average endocyclic angles (Se-C-C) facing the Se atom are 122.1 (5) and 122.2 (5)°. The Se atom is essentially coplanar with the attached benzene rings, deviating by 0.075 (1) and 0.091 (1) Å. In the two phenyl-ene(4-chloro-phen-yl)prop-2-en-1-one units, the benzene rings are inclined to each other by 44.6 (3) and 7.8 (3)°. In the crystal, the mol-ecules stack up the a axis, forming layers parallel to the ac plane. There are no significant classical inter-molecular inter-actions present. Hirshfeld surface analysis, two-dimensional fingerprint plots and the mol-ecular electrostatic potential surface were used to analyse the crystal packing. The Hirshfeld surface analysis suggests that the most significant contributions to the crystal packing are by C⋯H/H⋯C contacts (17.7%).

Crystal structure and Hirshfeld surface analysis of (Z)-4-(4-hy-droxy-benzyl-idene)-3-methyl-isoxazol-5(4H)-one.

The title compound, C11H9NO3, contains an isoxazole and a hy-droxy-benzyl-idene ring, which are inclined to each another by 3.18 (8)°. There is an intra-molecular C-H⋯O contact forming an S(7) ring. In the crystal, mol-ecules stack head-to-tail in columns along the b-axis direction, linked by offset π-π inter-actions [inter-centroid distances of 3.676 (1) and 3.723 (1) Å]. The columns are linked by O-H⋯O and O-H⋯N hydrogen bonds, forming layers parallel to the ab plane. The layers are linked by C-H⋯O hydrogen bonds, forming a supra-molecular three-dimensional framework. An analysis of the Hirshfeld surfaces points to the importance of the O-H⋯O and O-H⋯N hydrogen bonding in the packing mechanism of the crystal structure.

Crystal structure and Hirshfeld surface analysis of N-[(2-hy-droxy-naphthalen-1-yl)(3-methyl-phen-yl)meth-yl]acetamide.

The title compound, C20H19NO2, is of inter-est as a precursor to biologically active substituted quinolines and related compounds. This compound crystallizes with two independent mol-ecules (A and B) in the asymmetric unit. The dihedral angles between mean planes of the methyl-phenyl ring and the naphthalene ring system are 78.32 (6) and 84.70 (6)° in mol-ecules A and B, respectively. In the crystal, the anti-ferroelectric packing of mol-ecules A and B is of an ABBAABB type along the b-axis direction. The crystal structure features N-H⋯O, O-H⋯O and weak C-H⋯O hydrogen bonds, which link the mol-ecules into infinite chains propagating along the b-axis direction.

Crystal structure of ethyl 2-cyano-2-(1,3-di-thian-2-yl-idene)acetate.

The title compound, C9H11NO2S2, contains a 1,3-di-thiane ring which has a twist-boat conformation. The dihedral angle between the mean planes of the ethyl acetate group and the di-thiane ring is 17.56 (13)°. In the crystal, mol-ecules stack in layers up the a-axis direction, however, there are no significant inter-molecular inter-actions present.

Anharmonic Computations Meet Experiments (IR, Raman, Neutron Diffraction) for Explaining the Behavior of 1,3,5-Tribromo-2,4,6-trimethylbenzene.

In the present paper we first show the experimental Raman, infrared, and neutron INS spectra of tribromomesitylene (TBM) measured in the range 50-3200 cm(-1) using crystalline powders at 6 or 4 K. Then, the bond lengths and angles determined by neutron diffraction using a TBM single crystal at 14 K are compared to the computed ones at different levels of theory. Anharmonic computations were then performed on the relaxed structure using the VPT2 approach, and for the lowest normal modes, the HRAO model has led to a remarkable agreement for the assignment of the experimental signatures. A particularity appears for frequencies below 150 cm(-1), and in particular for those concerning the energy levels of "hindered rotation" of the three methyl groups, they must be calculated for one-dimensional symmetrical tops independent of the frame vibrations. This fact is consistent with the structure established by neutron diffraction: the protons of the methyl groups undergoing huge "libration" motions are widely spread in space. The values of the transitions between the librational levels determined by inelastic neutron scattering indicate that the hindering potentials are mainly due to intermolecular interactions different for each methyl group in the triclinic cell.

Crystal structure of 1,3,5-trimethyl-2,4-di-nitro-benzene.

In the title compound, C9H10N2O4, the planes of the nitro groups subtend dihedral angles of 55.04 (15) and 63.23 (15)° with that of the aromatic ring. These tilts are in opposite senses and the mol-ecule possesses approximate mirror symmetry about a plane normal to the mol-ecule. In the crystal, mol-ecules form stacks in the [100] direction with adjacent mol-ecules related by translation, although the centroid-centroid separation of 4.136 (5) Šis probably too long to regard as a significant aromatic π-π stacking inter-action. An extremely weak C-H⋯O inter-action is also present.

Crystal structure of 4,6-di-chloro-5-methyl-pyrimidine.

The title compound, C5H4Cl2N2, is essentially planar with an r.m.s. deviation for all non-H atoms of 0.009 Å. The largest deviation from the mean plane is 0.016 (4) Šfor an N atom. In the crystal, mol-ecules are linked by pairs of C-H⋯N hydrogen bonds, forming inversion dimers, enclosing an R (2) 2(6) ring motif.

Crystal structure of 1,1'-[selanediyl-bis(4,1-phenyl-ene)]bis-(2-chloro-ethan-1-one).

In the title mol-ecule, C16H12Cl2O2Se, the C-Se-C angle is 100.05 (14)°, with the dihedral angle between the planes of the benzene rings being 69.92 (17)°. The average endocyclic angles (Se-Car-Car; ar = aromatic) facing the Se atom are 120.0 (3) and 119.4 (3)°. The Se atom is essentially coplanar with the benzene rings, with Se-Car-Car-Car torsion angles of -179.2 (3) and -179.7 (3)°. In the crystal, mol-ecules are linked via C-H⋯O hydrogen bonds forming chains propagating along the a-axis direction. The chains are linked via C-H⋯π inter-actions, forming a three-dimensional network.

Iodo-durene.

THE TITLE COMPOUND (SYSTEMATIC NAME: 1-iodo-2,3,5,6-tetra-methyl-benzene), C10H13I, crystallizes in the chiral space group P212121. The I atom is displaced by 0.1003 (5) Šfrom the mean plane of the ten C atoms [maximum deviation = 0.018 (6) Å]. In the crystal, there are no significant inter-molecular inter-actions present.

Bis(4-acetyl-phen-yl) selenide.

In the title compound, C(16)H(14)O(2)Se, the dihedral angle between the benzene rings is 87.08 (11)°. In the crystal, mol-ecules are linked into layers parallel to the bc plane by inter-molecular C-H⋯O hydrogen bonds.

Rotationally disordered phase of 1,3-dibromo-5-iodo-2,4,6-trimethylbenzene at 293 K.

In the crystal state at room temperature, the molecule of dibromoiodomesitylene (1,3-dibromo-5-iodo-2,4,6-trimethylbenzene), C9H9Br2I, is prone to strong disorder, apparently involving only the three halogen sites (occupied identically by 66.7% Br and 33.3% I). This disorder, of the rotational type according to previously published NMR measurements, corresponds to fast 2pi/3 stochastic in-plane reorientations of the whole molecule between three discernable locations. This kind of rotational disorder can be revealed for the first time by diffractometry thanks to the C2v idealized molecular symmetry of the title compound, although it has been indirectly suspected at room temperature in other trihalogenomesitylenes of similar crystal packing but of D3h molecular symmetry. The average endocyclic angles facing the Br/I sites and the methyl groups are 124.14 (6) and 115.85 (2) degrees, respectively. The angle between the normal to the aromatic ring and the normal to the (100) plane is 4.1 degrees. TLS analysis indicates that only the aromatic ring and the methyl groups behave as a rigid body with respect to the thermal librations.