Symmetry-related Pyridine Rings Research Articles

The crystal structures and Hirshfeld surface analysis of N',N'''-((1E,1'E)-{[methyl-enebis(-oxy)]bis-(6-bromo-3,1-phenyl-ene)}bis-(methan-ylyl-idene))bis-(isonicotinohydrazide) dihydrate and N',N'''-((1E,1'E)-{[butane-1,4-diylbis(-oxy)]bis-(2,1-phenyl-ene)}bis-(methan-ylyl-idene))bis-(isonicotino-hydrazide) [+ solvent

The title compounds, C27H20Br2N6O4·2H2O, (I), and C30H28N6O4·[+ solvent], (II), both crystallize with one half-mol-ecule in the asymmetric unit. The whole mol-ecule of (I) is generated by twofold rotation symmetry, with the twofold rotation axis bis-ecting the C atom of the -O-CH2-O- bridge. This results in a folded or U-shaped conformation of the mol-ecule. The whole mol-ecule of (II) is generated by inversion symmetry, with the central CH2-CH2 bond of the -O-(CH2)4-O- bridge being located about a center of inversion. This results in a step-like conformation of the mol-ecule. The central C(=O)N-N=C regions of the isonicotinohydrazide moieties in both compounds are planar and the configuration about the imine C=N bonds is E. In compound (I), the benzene and pyridine rings are inclined to each other by 37.60 (6)°. The two symmetry-related pyridine rings are inclined to each other by 74.24 (6)°, and the two symmetry-related benzene rings by 7.69 (6)°. In compound (II), the benzene and pyridine rings are inclined to each other by 25.56 (11)°. The symmetry-related pyridine rings are parallel, as are the two symmetry-related benzene rings. In the crystal of (I), a pair of water mol-ecules link the organic mol-ecules via Owater-H⋯O and Owater-H⋯N hydrogen bonds, forming chains along [001], and enclosing an R 4 2(8) and two R 1 2(5) ring motifs. The chains are linked by N-H⋯Npyridine hydrogen bonds, forming a supra-molecular framework. There are also a number of C-H⋯O hydrogen bonds, and C-H⋯π and offset π-π inter-actions [inter-planar distance = 3.294 (1) Å] present reinforcing the framework. In the crystal of (II), mol-ecules are linked by N-H⋯Npyridine hydrogen bonds, forming a supra-molecular framework. Here too there are also a number of C-H⋯O hydrogen bonds present, and a C-H⋯π inter-action, reinforcing the framework. For compound (II), a region of disordered electron density was corrected for using the SQUEEZE [Spek (2015 ▸). Acta Cryst. C71, 9-18] routine in PLATON. Their formula mass and unit-cell characteristics were not taken into account during refinement.

Ethyl 2-{3-[(6-chloropyridin-3-yl)methyl]-2-(nitroimino)imidazolidin-1-yl}acetate

In the title compound, C13H16ClN5O4, the imidazole ring is in a slight envelope conformation. The dihedral angle between the pyridine ring and the four essentially planar atoms [maximum deviation 0.015 (2) Å] of the imidazole ring is 80.8 (1)°. In, the crystal, weak C—H⋯O and C—H⋯N hydrogen bonds are present. In addition, there are weak π–π stacking inter­actions between symmetry-related pyridine rings with a centroid–centroid distance of 3.807 (1) Å.

Two succinic acid derivatives of 2-ethyl-6-methylpyridin-3-ol

Crystals of bis(2-ethyl-3-hydroxy-6-methylpyridinium) succinate-succinic acid (1/1), C(8)H(12)NO(+)·0.5C(4)H(4)O(4)(2-)·0.5C(4)H(6)O(4), (I), and 2-ethyl-3-hydroxy-6-methylpyridinium hydrogen succinate, C(8)H(12)NO(+)·C(4)H(5)O(4)(-), (II), were obtained by reaction of 2-ethyl-6-methylpyridin-3-ol with succinic acid. The succinate anion and succinic acid molecule in (I) are located about centres of inversion. Intermolecular O-H···O, N-H···O and C-H···O hydrogen bonds are responsible for the formation of a three-dimensional network in the crystal structure of (I) and a two-dimensional network in the crystal structure of (II). Both structures are additionally stabilized by π-π interactions between symmetry-related pyridine rings, forming a rod-like cationic arrangement for (I) and cationic dimers for (II).

4-({[(E)-Pyridin-3-ylmethylidene]amino}methyl)cyclohexanecarboxylic acid

The title compound, C14H18N2O2, contains two geometrically different mol­ecules in the asymmetric unit: the basal plane of the cyclo­hexane chair and the N-[pyridin-3-yl­methyl­idene]methanamine moiety are oriented at dihedral angles of 71.77 (7)° and 83.42 (8)°. In the crystal, the mol­ecules are linked by O—H⋯N hydrogen bonds, generating C(13) head-to-tail chains extending along the base vector [103]. R 2 2(26) ring motifs are formed due to the C—H⋯·O inter­actions that link neighbouring chains. There also exist π–π inter­actions [centroid–centroid separation = 3.6925 (12) Å] between the symmetry-related pyridine rings of one of the independent mol­ecules.

2,9-Bis(3,5-dimethyl-1H-pyrazol-1-yl-κN2)-1,10-phenanthroline-κ2N,N′]bis(thiocyanato-κN)cadmium(II)

In the title complex, [Cd(NCS)2(C22H20N6)], the CdII ion is in a CdN6 coordination geometry which is inter­mediate between octa­hedral and trigonal–prismatic. The dihedral angles formed between the mean planes of the pyrazole rings and the phenanthroline system are 15.74 (15) and 16.30 (13)°. In the crystal, there is a π–π stacking inter­action involving two symmetry-related pyrazole rings, with a centroid–centroid distance of 3.664 (3) Å. In addition, there is a relatively short inter­molecular contact between C atoms [C⋯C = 3.399 (6) Å] involving symmetry-related pyridine rings along the a axis.

2-Phenyl-2-(pyridin-2-yl)hexahydropyrimidine

The title compound, C15H17N3, was prepared by reaction of benzoyl­pyridine and hexahydropyrimidine. The 1,3-diazinane ring adopts a chair conformation with one N—H group axial and the other equatorial. The axial N—H group participates in very weak hydrogen bonding to the lone pair of electrons of the N atom with the equatorial H atom producing a very weakly hydrogen-bonded dimer. The pyridine N atom accepts an inter­nal hydrogen bond from the equatorial H atom. The phenyl ring adopts an equatorial position while the pyridine ring is axial. The phenyl ring exhibits a slight twist (ca 25°) relative to the hexahydropyrimidine ring. The pyridine ring stacks with symmetry-related pyridine rings.

N,N-Dicyclohexyl-2-(5,7-dichloro-8-quinolyloxy)acetamide

The mol­ecular and crystal structures of the title compound, C23H28Cl2N2O2, are very close to those of the bromine-substituted analogue N,N-dicyclo­hexyl-2-(5,7-dibromo-8-quinol­yloxy)acetamide. The two cyclo­hexyl groups adopt normal chair conformation. The amide N and C atoms have a planar configuration. The crystal packing is stabilized by inter­molecular C—H⋯O hydrogen bonds and aromatic π⋯π stacking inter­actions [centroid–centroid separation = 3.5715 (4) Å for symmetry-related pyridine rings]. In addition, the crystal structure exhibits Cl⋯Cl halogen contacts of 3.4675 (3) Å.

2,2′-[(2,2′-Bipyridine-3,3′-diyl)bis(nitrilomethylidyne)]diphenol

The title mol­ecule, C24H18N4O2, lies on a twofold rotation axis with a dihedral angle of 73.7 (1)° between the mean planes of the symmetry-related pyridine rings. The dihedral angle between unique benzene and pyridine rings is 8.0 (1)°. An intra­molecular O—H⋯N hydrogen bond may influence the mol­ecular conformation. In the crystal structure, there are weak π–π stacking inter­actions with a centroid–centroid distance of 3.7838 (15) Å.

Dichlorido[2,2'-(oxydimethyl-ene)dipyridine]copper(II).

In the title complex, [CuCl2(C12H12N2O)], the CuII ion is coordinated in a distorted trigonal-bipyramidal environment. In the crystal structure, there is a weak π–π stacking inter­action between symmetry-related pyridine rings, with a centroid-to-centroid distance of 3.8134 (17) Å. In addition, there is relatively close contact between the pyridine ring π-system and a symmetry-related CuII ion (Cu⋯centroid distance of 3.868 Å).

Di-μ-nicotinato-κ2N:O;κ2O:N-bis[aqua(ethylenediamine-κ2N,N′)(nicotinato-κN)cadmium(II)] dihydrate

The dinuclear mol­ecule of the title compound, [Cd2(C6H4NO2)4(C2H8N2)2(H2O)2]·2H2O, lies on an inversion centre and forms 12-membered (CdNC3O)2 metallacycles with the two Cd2+ ions bridged by two nicotinate ligands. Both Cd2+ ions display coordination polyhedra with a distorted octa­hedral geometry that includes two pyridine N atoms from bridging and terminal nicotinate anions, two amine N atoms from chelating ethylene­diamine ligands, carboxylate O atoms from bridging nicotinate anions and water O atoms. Inter­molecular O—H⋯O and N—H⋯O hydrogen bonds result in the formation of a three-dimensional network, and π–π stacking inter­actions are observed between symmetry-related pyridine rings of bridging as well as terminal nicotinate anions (the centroid–centroid distances are 3.59 and 3.69 Å, respectively, and the distances between parallel planes of the stacked pyridine rings are 3.53 and 3.43 Å, respectively). The two methylene groups of the ethylene­diamine ligand are disordered over two positions; the site occupancy factors are ca 0.8 and 0.2.

(Dicyanamido)[tris(2-pyridylmethyl)amine]zinc(II) perchlorate

In the title complex, [Zn(C2N3)(C18H18N4)]ClO4, the ZnII ion has a slightly distorted trigonal–bipyramidal ZnN5 coordination geometry. The crystal structure is stabilized by weak inter­molecular C—H⋯O and C—H⋯N hydrogen bonds. In addition, there are relatively close contacts between the O atoms of the perchlorate anion and symmetry-related pyridine rings [O⋯Cg = 3.179 (3) and 3.236 (3) Å, where Cg is the centroid of a pyridine ring], and between the terminal N atom of the dicyanamide ligand and pyridine rings [N⋯Cg = 3.381 (4)–3.761 (3) Å]. The central N atom of the dicyanamide ligand is disordered over two sites in an approximately 0.6:0.4 ratio.

Bis(2,2′-bipyridine-1κ2N,N′)-μ-bromido-1:2κ2Br-tribromido-2κ3Br-copper(II)mercury(II)

In the title compound, [CuHgBr4(C10H8N2)2], the CuII atom is coordinated by four N atoms of two bidentate 2,2′-bipyridine ligands and one Br atom of a tetra­bromido­mercurate anion in a distorted trigonal–bipyramidal geometry. The Br atom occupies an equatorial position and bridges the CuII and Hg atoms, with Hg—Br distances of 2.7503 (15) A, longer by more than 0.15 A than the terminal Hg—Br bonds. Weak π–π inter­actions between symmetry-related pyridine rings stabilize the packing; the shortest C—C distance between two parallel aromatic rings of bipy ligands is 3.491 (9) A.

An enriched hydrogen-bond system intrans-diaquabis(N,N-diethylnicotinamide-κN)bis(3-methoxysalicylato-κO)copper(II) dihydrate

In the mol­ecule of the title compound, [Cu(C8H7O4)2(C10H14N2O)2(H2O)2]·2H2O, the Cu2+ cation lies on an inversion centre. It is coordinated by two pairs of O atoms of 3-methoxy­salicylate anions and water mol­ecules, and one pair of pyridine N atoms of N,N-diethyl­nicotinamide ligands, forming a tetra­gonal–bipyramidal coordination polyhedron. The two water mol­ecules of solvation are linked to the complex mol­ecule by O—H⋯O and C—H⋯O hydrogen bonds. A π–π stacking inter­action is also observed between symmetry-related pyridine rings.

Tetrakis(4-nitropyridineN-oxide-κO)bis(perchlorato)copper(II)

In the title mononuclear complex, [Cu(ClO4)2(C5H4N2O3)4], the six-coordinated CuII ion lies on an inversion centre and presents a slightly distorted octa­hedral geometry. A π–π stacking inter­action is observed between symmetry-related pyridine rings.