Structural studies of N-(methoxysalicylidene)-fluoroaniline, N-(methoxysalicylidene)-chloroaniline and N-(methoxysalicylidene)-bromoaniline derivatives

Twenty seven N-(methoxysalicylidene)-haloaniline (halo = F, Cl or Br) compounds were synthesized. The crystal structures of all 27 compounds have been determined at low temperature and are reported herein, along with a variable-temperature neutron diffraction study on two of the compounds. New polymorphs were identified for two of the compounds along with a temperature-induced phase transition for one of the other compounds. Visual observations on the thermochromism of the 27 compounds are also reported. The interplanar angle between the two aromatic rings and the intermolecular interactions in the structures are examined and linked to the visual observations on the thermochromism.

Synthesis and crystal structures of N-H, N-phenyl and N-benzyl-2-(4-hexyloxyphenyl)benzimidazoles

The title compounds, 2-(4-hexyloxyphenyl)-1H-benzimidazole (C19H22N2O; 1), 2-(4-hexyloxyphenyl)-1-phenyl-1H-benzimidazole (C25H26N2O; 2) and 1-benzyl-2-(4-hexyloxyphenyl)-1H-benzimidazole (C26H28N2O; 3) were synthesized and their structures were determined by single-crystal X-ray analysis. The N-substituent at the imidazole moiety slightly affects the interplanar angle between the 4-hexyloxyphenyl ring and the benzimidazole system. The unsubstituted benzimidazole (1) forms intermolecular N—H...N bonds while in the crystal structures of 2 and 3, the molecules are assembled only through π–π and C—H...π interactions.

Δ9-Tetrahydrocannabinolic acid A, the precursor to Δ9-tetrahydrocannabinol (THC)

While Δ9-tetrahydrocannabinolic acid A (THCA-A) has been reported to be difficult to crystallize and/or amorphous, we have obtained THCA-A in a pure crystalline form by extraction of marijuana and selective fractionation with liquid CO2. THCA-A (systematic name: 1-hydroxy-6,6,9-trimethyl-3-pentyl-6a,7,8,10a-tetrahydro-6H-benzo[c]isochromene-2-carboxylic acid, C22H30O4) crystallizes in the orthorhombic space group P212121, with Z = 8 and Z′ = 2. The two independent molecules are related by a pseudo-twofold axis centered between the two –CO2H groups, but the conformations of the two –C5H11 chains are quite different (tgt and ttg; t is trans and g is gauche). The carboxylate groups form an intermolecular R 2 2(8) hydrogen-bonded ring; the two C2O2 carboxylate planes are twisted out of the planes of the attached arene rings in opposite directions by 13.59 (8) and 18.92 (8)°, respectively, with a resultant interplanar angle of 28.89 (8)°. Each molecule also has an intramolecular S(6) hydrogen-bond motif between the ortho –OH group and the dihydropyran-ring O atom. Other conformational aspects of the two independent molecules are quite similar to those found in the previously determined structure of THCA-B. THCA-A has shown promise in a number of medical applications. Demonstration of the crystallinity and details of the crystal structure are expected to provide a standard point of departure for chemical and medical experiments.

The Simplest Iron μ-oxo Species. The Molecular Structure of {[Fe(porphine)]2O}

We have prepared a new [Formula: see text]-oxo iron(III) porphyrin complex based on the simplest possible porphyrin ligand, porphine. Our structure determination for {[Fe(porphine)]2O}shows that it has a decidedly different molecular structure compared to all other [Formula: see text]-oxo iron(III)porphyrin complexes with two independent porphyrin ligands. The Fe–O–Fe angle is 153.21 (16)[Formula: see text]which leads to a small interplanar angle of 22.7[Formula: see text]between the two porphine rings. This also leads to C[Formula: see text]C nonbonded contact as short as 3.35Å between the two rings. The twist angle of the two porphine rings is 16.8[Formula: see text]. Other structural features are in general accord with those expected for high-spin iron(III) porphyrinates.

3-Ethoxy-5-phenyl-1H-1,2,4-triazole

The title compound, C10H11N3O, crystallizes in the triclinic space group P\overline{1} with Z′ = 2. The two independent molecules (A and B) differ in the orientation of the phenyl rings with respect to the plane of the triazine ring, with an interplanar angle of 11.45 (6)° in molecule A and 19.71 (5)° in molecule B, in the opposite sense. In the crystal, classical N—H...N hydrogen bonds cross-link the molecules to form chains parallel to the b axis. Two additional `weak' C—H...O hydrogen bonds link the chains to form layers parallel to (101).

Design of new anti-Alzheimer drugs: ring-expansion synthesis and synchrotron X-ray diffraction study of dimethyl 4-ethyl-11-fluoro-1,4,5,6,7,8-hexahydroazonino[5,6-b]indole-2,3-dicarboxylate

The title compound, C20H23FN2O4, is the product of a ring-expansion reaction from a seven-membered fluorinated hexahydroazepine to a nine-membered azonine. The nine-membered azonine ring of the molecule adopts achair–boatconformation. The C=C and C—N bond lengths [1.366 (3) and 1.407 (3) Å, respectively] indicate the presence of conjugation within the enamine CH2—C=C—N—CH2fragment. The substituent planes at the C=C double bond of this fragment are twisted by 16.0 (3)° as a result of steric effects. The amine N(Et) N atom has a trigonal–pyramidal configuration (sum of the bond angles = 346.3°). The interplanar angle between the two carboxylate substituents is 60.39 (8)°. In the crystal, molecules form zigzag chains along [010] by intermolecular N—H...O hydrogen-bonding interactions, which are further packed in stacks toward [100]. The title azoninoindole might be considered as a candidate for the design of new Alzheimer drugs.

1-(2-Bromo-4-methylphenyl)-3,3-dimethylthiourea

The bromomethylphenyl and dimethylthiourea groups of the molecule of the title compound, C10H13BrN2S, are inclined to one another at an interplanar angle of 55.13 (6)°. In the crystal, molecules are stacked along thebaxis and intermolecular N—H...S contacts form chains of molecules along [010].

Crystal structure ofN-[6-amino-5-(benzo[d]thiazol-2-yl)-3-cyano-4-methylsulfanyl-2-oxo-1,2-dihydropyridin-1-yl]-4-methylbenzenesulfonamide dimethylformamide monosolvate

In the title compound, C21H17N5O3S3·C3H7NO, the toluenesulfonamide ring and the combined ring system involving the pyridone and benzothiazole rings subtend an interplanar angle of 39.86 (4)°. The pyridone and benzothiazyl rings are linked by the intramolecular hydrogen bond N—Hamine...Nthiazole. The DMF O atom accepts two classical hydrogen bonds. The molecules are linked by hydrogen bonds and an S...O contact to form layers parallel to thebcplane.

Side-chain conformations in the isomorphous polyfluorinated {4,4′-bis[(2,2-difluoroethoxy)methyl]-2,2′-bipyridine-κ2 N,N′}dichloridopalladium and -platinum complexes

The polyfluorinated title compounds, [MCl2(C16H16F4N2O2)] or [4,4′-(HCF2CH2OCH2)2-2,2′-bpy]MCl2 [M = Pd, (1), and M = Pt, (2)], have –C(Hα)2OC(Hβ)2CF2H side chains with H-atom donors at the α and β sites. The structures of (1) and (2) are isomorphous, with the nearly planar (bpy)MCl2 molecules stacked in columns. Within one column, π-dimer pairs alternate between a π-dimer pair reinforced with C—H...Cl hydrogen bonds (α,α) and a π-dimer pair reinforced with C—Hβ...F(—C) interactions (abbreviated as C—Hβ...F—C,C—Hβ...F—C). The compounds [4,4′-(CF3CH2OCH2)2-2,2′-bpy]MCl2 [M = Pd, (3), and M = Pt, (4)] have been reported to be isomorphous [Lu et al. (2012). J. Fluorine Chem. 137, 54–56], yet with disorder in the fluorous regions. The molecules of (3) [or (4)] also form similar stacks, but with alternating π-dimer pairs between the (α,β; α,β) and (β,β) forms. Through (C—)H...Cl hydrogen-bond interactions, one molecule of (1) [or (2)] is expanded into an aggregate of two inversion-related π-dimer pairs, one pair in the (α,α) form and the other pair in the (C—Hβ...F—C,C—Hβ...F—C) form, with the plane normals making an interplanar angle of 58.24 (3)°. Due to the demands of maintaining a high coordination number around the metal-bound Cl atoms in molecule (1) [or (2)], the ponytails of molecule (1) [or (2)] bend outward; in contrast, the ponytails of molecule (3) [or (4)] bend inward.

Crystal structure ofN′-[2-(benzo[d]thiazol-2-yl)acetyl]-4-methylbenzenesulfonohydrazide

In the title compound, C16H15N3O3S2, the hydrazide N atom bonded to the C=O group is planar, whereas that bonded to the SO2group is pyramidally coordinated. The interplanar angle between the ring systems is 40.71 (3)°. Molecules are connected into ribbons parallel to thebaxis by two classical hydrogen bonds N—H...O=C and N—H...Nthiazole.