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1.  (E)-2-[1-(1-Benzothio­phen-2-yl)ethyl­idene]-N-phenyl­hydrazinecarboxamide 
The title compound, C17H15N3OS, crystallizes with two unique mol­ecules, denoted 1 and 2, in the asymmetric unit. The two mol­ecules are closely similar and overlay with an r.m.s. deviation of 0.053 Å. Both mol­ecules adopt E configurations with respect to the C=N bonds. The dihedral angles between the benzothio­phene groups and N-bound phenyl rings are 36.36 (9)° for mol­ecule 1 and 29.71 (9)° for mol­ecule 2. The C=N—NH—C(O)NH ethyl­idene–hydrazinecarboxamide units are also reasonably planar, with r.m.s. deviations of 0.061 and 0.056 Å, respectively, for the two mol­ecules. The methyl substituents lie 0.338 (3) and 0.396 (3) Å, respectively, from these planes. The C=N—NH—C(O)NH planes are inclined to the phenyl rings at 13.65 (11) and 15.56 (11)°, respectively, in mol­ecules 1 and 2. This conformation is enhanced by weak intra­molecular C—H⋯O hydrogen bonds between ortho-H atoms of the two phenyl rings and the carbonyl O atoms, which generate S(6) rings in each mol­ecule. In the crystal, pairs of mol­ecules are linked by pairs of inter­molecular N—H⋯O hydrogen bonds into dimers. Alternating dimers are further inter­connected by weak C—H⋯O contacts into zigzag rows along b. The rows are stacked along a by C—H⋯π contacts involving the benzene ring from molecule 2 and the thiophene ring from molecule 1 of adjacent benzothio­phene units.
PMCID: PMC3201294  PMID: 22058789
2.  6-{5-Amino-3-tert-butyl-4-[(E)-(3-methyl-1,2,4-thiadiazol-5-yl)diazen­yl]-1H-pyrazol-1-yl}-1,3,5-triazine-2,4(1H,3H)-dione–1-methyl­pyrrolidin-2-one–water (1/1/1) 
In the title compound, C13H16N10O2S·C5H9NO·H2O, the entire 1-methylpyrrolidin-2-one (NMP) mol­ecule is disordered over two sites with occupancies of 0.488 (5) and 0.512 (5). The six-membered triazine ring and the two five-membered pyrazole and thiadia­zole rings, together with the diazene (–N=N–) linkage are almost coplanar (r.m.s. deviation for the non-H atoms = 0.0256 Å) with methyl groups from the tert-butyl substituent on the pyrazole ring located above and below the plane. Three intra­molecular N—H⋯N hydrogen bonds contribute to the planarity of the system. The O atom of the NMP mol­ecule is hydrogen bonded to an O—H group of water. In turn, the water mol­ecule is hydrogen bonded to the mono-azo skeleton through inter­molecular N—H⋯O and O—H⋯N hydrogen bonds. At both ends of the long mol­ecular axis of the main mol­ecule there are inter­molecular N—H⋯N hydrogen bonds, arranged in a head-to-tail fashion, between the N—H group of the triazine ring of one mol­ecule and the N atom of the thia­diazole ring of a neighboring mol­ecule. These form a polymeric chain along [110] or [10]. The main mol­ecules are stacked alternately along the b axis, which effectively cancels their dipole moments. In addition, pairs of alternate molecules are dimerized via inter­molecular hydrogen bonds involving the solvent mol­ecules.
PMCID: PMC2983887  PMID: 21580749
3.  5-Chloro-N-(4,5-dihydro-1H-imidazol-2-yl)-2,1,3-benzothia­diazol-4-amine (tizanidine) 
There are two independent mol­ecules (A and B) with similar conformations in the asymmetric unit of the title compound, C9H8ClN5S. The benzothia­diazole ring systems of both mol­ecules are essentially planar [maximum deviation = 0.021 (2) Å in mol­ecule A and 0.022 (1) Å in mol­ecule B] and make dihedral angles of 68.78 (9) and 54.39 (8)°, respectively, with the mean planes of their 4,5-dihydro-1H-imidazole rings. An intra­molecular N—H⋯Cl hydrogen bond occurs in mol­ecule B. In the crystal, both mol­ecules form centrosymmetric dimers through π-stacking of their benzothia­diazole rings, with inter­planar distances of 3.3174 (7) and 3.2943 (6) Å. These dimers are further linked via pairs of N—H⋯N hydrogen bonds with the dihydro­imidazole rings as the hydrogen-bonding donors and one of the benzothia­diazole N atoms as the acceptors, generating R 2 2(16) ring motifs. The A 2 and B 2 dimers in turn form additional N—H⋯N hydrogen bonds with the secondary amine as the H-atom donor and the dihydro­imidazole N atom as the acceptor. These R 2 2(8)-type inter­actions connect the A 2 and B 2 dimers with each other, forming infinite chains along [11].
PMCID: PMC3100067  PMID: 21754121
4.  Crystal structure of 4-(tri­methyl­germ­yl)benzoic acid 
During synthesis of the corresponding aldehyde, 4-(tri­methyl­germ­yl)benzoic acid was obtained as a side-product. It crystallizes with two independent mol­ecules in the asymmetric unit which exhibit slightly different geometries. In the crystal structure, centrosymmetric hydrogen-bonded dimers of the mol­ecular pairs are formed.
The title compound, [Ge(CH3)3(C7H5O2)], was obtained as a by-product in the synthesis of the corresponding aldehyde. Two slightly different mol­ecules are present in the asymmetric unit. In both mol­ecules, the geometry of the aromatic ring plane is distorted by varying intensities. Additionally, the Ge atoms deviate from the mean aromatic ring planes. Whereas the distance of the Ge atom to the ring plane is only 0.101 (4) Å in the first mol­ecule, this distance is increased to 0.210 (4) Å in the second. In the crystal structure, centrosymmetric O—H⋯O hydrogen-bonded dimers are formed. The title compound is isostructural with the Si analogue [Haberecht et al. (2004 ▶). Acta Cryst. E60, o329–0330].
PMCID: PMC4459299  PMID: 26090151
crystal structure; 4-(tri­methyl­germ­yl)benzoic acid; germanium; hydrogen bonding
5.  3,3,3′,3′-Tetra­methyl-6,6′-bis­[(pyridin-4-yl)meth­oxy]-1,1′-spiro­biindane ­monohydrate 
The asymmetric unit in the title compound, C33H34N2O2·H2O, consists of a V-shaped mol­ecule and a water mol­ecule to which it is hydrogen bonded. The angle between the mean planes of the two spiro-connected indane groups is 77.06 (5)°. The two five-membered rings of the indane groups have envelope conformations with the methyl­ene atoms adjacent to the spiro C atom forming the flaps. They have deviations from the mean plane of the other four atoms in the rings of 0.374 (4) and 0.362 (4) Å. In the crystal, molecules are linked to form inversion dimers via O—H⋯N hydrogen bonds involving the pyridine N atoms and the solvent water mol­ecule. The dimers are linked into a chain along the b axis by π–π stacking inter­actions between a pyridine ring and its centrosymmetrically related ring in an adjacent dimer. The centroid–centroid distance between the planes is 3.7756 (17) Å, the perpendicular distance is 3.4478 (11) Å and the offset is 1.539 Å.
PMCID: PMC3379348  PMID: 22719546
6.  Ethyl 2-[4-(morpholin-4-yl)phen­yl]-1-[3-(2-oxopyrrolidin-1-yl)prop­yl]-1H-1,3-benzimidazole-5-carboxyl­ate monohydrate 
The asymmetric unit of the title compound, C27H32N4O4·H2O, contains two independent benzimidazole-5-carboxyl­ate mol­ecules and two water mol­ecules. In both main mol­ecules, the pyrrolidine rings are in an envelope conformation with a methyl­ene C atom as the flap. The morpholine rings adopt chair conformations. Both benzimidazole rings are essentially planar, with maximum deviations of 0.008 (1) Å, and form dihedral angles of 37.65 (6) and 45.44 (6)° with the benzene rings. In one mol­ecule, an intra­molecular C—H⋯O hydrogen bond forms an S(7) ring motif. In the crystal, O—H⋯O and O—H⋯N hydrogen bonds connect pairs of main mol­ecules and pairs of water mol­ecules into two independent centrosymmetric four-compoment aggregates. These aggregates are connect by C—H⋯O hydrogen bonds leading to the formation of a three-dimensional network, which is stabilized by C—H⋯π interactions.
PMCID: PMC3470336  PMID: 23125749
7.  Poly[[diaqua­bis­[μ4-5-nitro­isophthalato-κ4 O 1:O 1:O 3:O 3′]bis­[μ3-pyridine-4-carboxyl­ato-κ3 O:O′:N]tricobalt(II)] tetra­hydrate] 
The title compound, {[Co3(C6H4NO2)2(C8H3NO6)2(H2O)2]·4H2O}n, exhibits a two-dimensional layer-like structure in which the CoII ions exhibit two kinds of coordination geometries. One nearly octa­hedral CoII ion with crystallographic inversion symmetry is coordinated to six carboxyl­ate O atoms from four bridging 5-nitro­isophthalate (NIPH) ligands and two isonicotinate (IN) anions, while the other type of CoII ion binds with one N atom and one carboxyl­ate O atom from two IN anions, two carboxyl­ate O atoms from two different NIPH anions and one ligated water mol­ecule, displaying a distorted square-pyramidal coordination geometry. Three adjacent CoII ions are bridged by six carboxyl­ate groups from four NIPH ligands and two IN anions to form a linear trinuclear secondary building unit (SBU). Every trinuclear SBU is linked to its nearest neighbours in the ab plane, resulting in a two-dimensional layer-like structure perpendicular to the c axis. Along the a-axis direction neighbouring mol­ecules are connected through carboxyl­ate and pyridyl units of the IN anions, along the b axis through carboxyl­ate groups of the NIPH ligands. The H atoms of one free water mol­ecule are disordered in the crystal in a 1:1 ratio. Typical O—H⋯O hydrogen bonds are observed in the lattice, which include the following contacts: (a) between coordinated water mol­ecules and carboxyl­ate O atoms of the NIPH anions, (b) between lattice water mol­ecules and carboxyl­ate O atoms of the NIPH anions, and (c) between coordinated and lattice water mol­ecules. These inter­molecular hydrogen bonds connect the two-dimensional layers to form a three-dimensional supra­molecular structure.
PMCID: PMC3343849  PMID: 22589823
8.  Bis(3,5-dimethyl-1H-pyrazole-κN 2)bis­(3,3′′,5,5′′-tetra­methyl-[1,1′:3′,1′′-terphen­yl]-2′-carboxyl­ato-κO)iron(II) dichloro­methane monosolvate 
In the title compound, [Fe(C23H21O2)2(C5H8N2)2]·CH2Cl2, the Fe2+ cation is coordinated by the N atoms of two 3,5-dimethyl­pyrazole ligands and the carboxyl­ate O atoms from two tetra­methyl­terphenyl­carboxyl­ate ligands, forming an FeN2O2 polyhedron with a slightly distorted tetra­hedral coordination geometry. Intra­molecular N—H⋯O and C—H⋯O hydrogen-bonding inter­actions stabilize the mol­ecular conformation. The dihedral angles formed by the central benzene ring with the outer benzene rings of the terphenyl groups are 47.92 (8), 59.38 (8), 48.24 (8) and 52.37 (8)°. The dichloro­methane solvent mol­ecule inter­acts with the complex mol­ecule via a C—H⋯O hydrogen bond. In the crystal, centrosymmetrically related complex mol­ecules are linked into dimers through pairs of C—H⋯O hydrogen bonds.
PMCID: PMC3344361  PMID: 22590127
9.  A series of N-(2-phenyl­ethyl)nitro­aniline derivatives as precursors for slow and sustained nitric oxide release agents 
A series of N-(2-phenyl­ethyl)nitro­aniline derivatives is presented, demonstrating that modest changes in the functional groups cause significant differences in mol­ecular conformation, inter­molecular inter­actions and packing.
2,4-Di­nitro-N-(2-phenyl­ethyl)aniline, C14H13N3O4, (I), crystallizes with one independent mol­ecule in the asymmetric unit. The adjacent amine and nitro groups form an intra­molecular N—H⋯O hydrogen bond. The anti conformation about the ethyl C—C bond leads to the phenyl and aniline rings being essentially parallel. Mol­ecules are linked into dimers by inter­molecular N—H⋯O hydrogen bonds, such that each amine H atom participates in a three-centre inter­action with two nitro O atoms. Though the dimers pack so that the arene rings of adjacent mol­ecules are parallel, the rings are staggered and π–π inter­actions do not appear to be favoured. 4,6-Di­nitro-N,N′-bis­(2-phenyl­ethyl)benzene-1,3-di­amine, C22H22N4O4, (II), differs from (I) in the presence of a second 2-phenyl­ethyl­amine group on the substituted ring. Compound (II) also crystallizes with one unique mol­ecule in the asymmetric unit. Both amine groups are involved in intra­molecular N—H⋯O hydrogen bonds with adjacent nitro groups. Although one ethyl group adopts an anti conformation as in (I), the other is gauche, with the result that the pendant phenyl rings are not parallel. The amine group that is part of the gauche conformation participates in a three-centre N—H⋯O hydrogen bond with the nitro group of a neighbouring mol­ecule, leading to dimers as in (I). The other amine H atom does not form any inter­molecular hydrogen bonds. The packing leads to separations of ca 3.4 Å of the parallel anti phenyl and amino­benzene rings. 2-Cyano-4-nitro-N-(2-phenyl­ethyl)aniline, C15H13N3O2, (III), differs from (I) only in having a cyano group in place of the 2-nitro group. The absence of the adjacent nitro group eliminates the intra­molecular N—H⋯O hydrogen bond. Mol­ecules of (III) adopt the same anti conformation about the ethyl group as in (I), but crystallize in the higher-symmetry monoclinic space group P21/n. The mol­ecules are linked into dimers via N—H⋯N amine–cyano hydrogen bonds, while the nitro groups are not involved in any N—H⋯O inter­actions. Owing to the different symmetry, the mol­ecules pack in a herringbone pattern with fewer face-to-face inter­actions between the rings. The closest such inter­actions are about 3.5 Å between rings that are largely slipped past one another. 4-Methyl­sulfonyl-2-nitro-N-(2-phenyl­ethyl)aniline, C15H16N2O4S, (IV), differs from (I) in having a methyl­sulfonyl group in place of the 4-nitro group. The intra­molecular N—H⋯O hydrogen bond is present as in (I). However, unlike (I), the conformation about the ethyl group is gauche, so the two arene rings are nearly per­pen­dicular rather than parallel. The packing is significantly different from the other three structures in that there are no inter­molecular hydrogen bonds involving the N—H groups. The mol­ecules are arranged in tetra­gonal columns running along the c axis, with the aniline rings mostly parallel and separated by ca 3.7 Å. Taken together, these structures demonstrate that modest changes in functional groups cause significant differences in mol­ecular conformation, inter­molecular inter­actions and packing.
PMCID: PMC3818095  PMID: 24192194
crystal structure; N-(2-phenyl­ethyl)nitro­aniline derivatives; secondary amines; nitric oxide release agents
10.  3-Acetyl­benzoic acid 
In the crystal structure of the title compound, C9H8O3, essentially planar mol­ecules [the carboxyl group makes a dihedral angle of 4.53 (7)° with the plane of the ring, while the acid group forms a dihedral angle of 3.45 (8)° to the ring] aggregate by centrosymmetric hydrogen-bond pairing of ordered carboxyl groups. This yields dimers which have two orientations in a unit cell, creating a herringbone pattern. In addition, two close C—H⋯O inter­molecular contacts exist: one is between a methyl H atom and the ketone of a symmetry-related mol­ecule and the other involves a benzene H atom and the carboxyl group O atom of another mol­ecule. The crystal studied was a non-merohedral twin with twin law [100, 00, 0] and a domain ratio of 0.8104(14): 0.1896(14).
PMCID: PMC3006848  PMID: 21587832
11.  Ethyl 4-(2,4-difluoro­phen­yl)-6-methyl-1-phenyl-2-thioxo-1,2,3,4-tetra­hydro­pyrimidine-5-carboxyl­ate 
The asymmetric unit of the title compound, C20H18F2N2O2S, contains four independent mol­ecules, two of which are paired into a dimer by way of two N—H⋯S hydrogen bonds. The other two independent mol­ecules are paired into two centrosymmetric dimers via pairs of inter­molecular N—H⋯S hydrogen bonds. In one mol­ecule, the carboxyl­ate O atoms, methyl­ene and methyl groups attached to the benzene ring are disordered between two positions in a 0.908 (3):0.092 (3) ratio. In two of the independent mol­ecules, the F and H atoms of the diflourophenyl ring are flip-flop disordered (i.e. by 180° about the C—C bond axis linking the ring to the rest of the molecule) in a 3:2 ratio. The crystal packing is stabilized by weak inter­molecular C—H⋯O hydrogen bonds.
PMCID: PMC2977677  PMID: 21584020
12.  Penta­kis­(μ3-N,2-di­oxido­benzene-1-car­box­imid­ato)di-μ2-formato-penta­kis­(1H-imidazole)­methanolpenta­manganese(III)man­gan­ese(II)–methanol–water (1/3.36/0.65) 
The title compound, [Mn6(C7H4NO3)5(CHO2)2(C3H4N2)5(CH3OH)]·3.36CH3OH·0.65H2O, or Mn(II)(O2CH)2[15-MCMn(III)N(shi)-5](Im)5(MeOH)·3.36MeOH·0.65H2O (where MC is metallacrown, shi3− is salicyl­hydroximate, Im is imidazole and MeOH is methanol), contains five MnIII ions as members of the metallacrown ring and an MnII atom bound in the central cavity. The central MnII atom is seven-coordinate with a geometry best described as between face-capped trigonal–prismatic and face-capped octa­hedral. Three MnIII ions of the metallacrown ring are six-coordinate with distorted octa­hedral geometries. Of these six-coordinate MnIII ions, two have mirror-plane configurations, while the other has a Δ absolute stereoconfiguration. The remaining two MnIII ions have a coordination number of five with a distorted square-pyramidal geometry. The five imidazole ligands are bound to five different MnIII ions. Disorder is observed for one of the coordinating imidazole ligands, as the imidazole ligand is disordered over two alternative mutually exclusive positions in a ratio of 0.672 (9) to 0.328 (9). The inter­stitial voids between the main mol­ecules that constitute the structure are mostly filled with methanol mol­ecules that form hydrogen-bonded chains. Some of the sites of the non-coordinated methanol mol­ecules are not fully occupied, with the remainder of the volume either empty or taken up by ill-defined close to amorphous content. One site was refined as being taken up by either two or one methanol mol­ecules, with an occupancy ratio of 0.628 (5) to 0.343 (5). This disorder might thus be correlated with the disorder of the imidazole ring (an N—H⋯O hydrogen bond between the major moieties of the imidazole and the methanol mol­ecules is observed). On the other side of the disordered imidazole ring the chain of partially occupied methanol mol­ecules originates that extends via O—H⋯O hydrogen bonds to the metal-coordinated methanol mol­ecule. The three partially occupied methanol mol­ecules were refined to be disordered with two water mol­ecules to take two residual electron density peaks into account (the exact nature of these weak residual electron density peaks cannot be deduced from the X-ray diffraction data alone, the assignment as water is tentative). The occupancy rate for the methanol mol­ecules refined to 0.480 (7). The occupancy rate of the two water mol­ecules refined to 0.34 (1) and 0.31 (2) for each site.
PMCID: PMC3588767  PMID: 23468732
13.  Bis(2,2′-bipyridine-κ2 N,N′)(3-methyl­benzoato-κ2 O,O′)zinc 3-methyl­benzo­ate–3-methyl­benzoic acid–water (1/1/2) 
The title compound, [Zn(C8H7O2)(C10H8N2)2](C8H7O2)·C8H8O2·2H2O, is comprised of a Zn2+ cation, two 2,2′-bipydine (bipy) ligands and one 3-methyl­benzoate anion (L −) together with one uncoordinating L − anion, one uncoordinating HL mol­ecule and two lattice water mol­ecules. The ZnII atom is coordinated by four N atoms of two bipy ligands and two O atoms from one L − ligand in a distorted octa­hedral geometry. Pairs of centrosymmetrically related complex mol­ecules form dimers via slipped π-stacking inter­actions between bipy ligands with an inter­planar distance of 3.470 (4) Å. The dimers are linked into supra­molecular chains along [111], via C—H⋯O hydrogen bonds. The uncoordinated L − anions, HL mol­ecules and water mol­ecules are connected with each other via O—H⋯O hydrogen bonds, forming chains between the metal complex chains and binding them together via C—H⋯O contacts. The resulting layers parallel to (010) are further assembled into a three-dimensional supra­molecular architecture through additional C—H⋯O inter­actions.
PMCID: PMC3435584  PMID: 22969457
14.  3-Phenyl-1-(pyrrol-2-yl)prop-2-en-1-one 
The title mol­ecule, C13H11NO, is almost flat, the angle between the pyrrole and the phenyl rings being 10.9 (1)°. The atoms of the central C3O unit are coplanar, with a mean deviation from the plane of 0.001 (1) Å. The angles between this plane and the pyrrole and phenyl rings are 3.3 (1) and 8.0 (1)°, respectively. The mol­ecules form centrosymmetric dimers through a pair of N—H⋯O hydrogen bonds with an R 2 2(10) motif.
PMCID: PMC2915219  PMID: 21200716
15.  Crystal structures of trans-di­chlorido­tetra­kis­[1-(2,6-diiso­propyl­phen­yl)-1H-imidazole-κN 3]iron(II), trans-di­bromido­tetra­kis­[1-(2,6-diiso­propyl­phen­yl)-1H-imidazole-κN 3]iron(II) and trans-di­bromido­tetra­kis­[1-(2,6-diiso­propyl­phen­yl)-1H-imidazole-κN 3]iron(II) diethyl ether disolvate1  
The title compounds are iron(II) dihalide complexes of the bulky arylimidazole ligand 1-(2,6-diisopropylphenyl)-1H-imidazole. The FeCl2 and FeBr2 complexes are isotypic, while the third compound, also an FeBr2 complex, crystallizes as a diethyl ether disolvate.
The title compounds, [FeCl2(C15H20N2)4], (I), [FeBr2(C15H20N2)4], (II), and [FeBr2(C15H20N2)4]·2C4H10O, (IIb), respectively, all have triclinic symmetry, with (I) and (II) being isotypic. The FeII atoms in each of the structures are located on an inversion center. They have octa­hedral FeX 2N4 (X = Cl and Br, respectively) coordination spheres with the FeII atom coordinated by two halide ions in a trans arrangement and by the tertiary N atom of four aryl­imidazole ligands [1-(2,6-diiso­propyl­phen­yl)-1H-imidazole] in the equatorial plane. In the two independent ligands, the benzene and imidazole rings are almost normal to one another, with dihedral angles of 88.19 (15) and 79.26 (14)° in (I), 87.0 (3) and 79.2 (3)° in (II), and 84.71 (11) and 80.58 (13)° in (IIb). The imidazole rings of the two independent ligand mol­ecules are inclined to one another by 70.04 (15), 69.3 (3) and 61.55 (12)° in (I), (II) and (IIb), respectively, while the benzene rings are inclined to one another by 82.83 (13), 83.0 (2) and 88.16 (12)°, respectively. The various dihedral angles involving (IIb) differ slightly from those in (I) and (II), probably due to the close proximity of the diethyl ether solvent mol­ecule. There are a number of C—H⋯halide hydrogen bonds in each mol­ecule involving the CH groups of the imidazole units. In the structures of compounds (I) and (II), mol­ecules are linked via pairs of C—H⋯halogen hydrogen bonds, forming chains along the a axis that enclose R 2 2(12) ring motifs. The chains are linked by C—H⋯π inter­actions, forming sheets parallel to (001). In the structure of compound (IIb), mol­ecules are linked via pairs of C—H⋯halogen hydrogen bonds, forming chains along the b axis, and the diethyl ether solvent mol­ecules are attached to the chains via C—H⋯O hydrogen bonds. The chains are linked by C—H⋯π inter­actions, forming sheets parallel to (001). In (I) and (II), the methyl groups of an isopropyl group are disordered over two positions [occupancy ratio = 0.727 (13):0.273 (13) and 0.5:0.5, respectively]. In (IIb), one of the ethyl groups of the diethyl ether solvent mol­ecule is disordered over two positions (occupancy ratio = 0.5:0.5).
PMCID: PMC4158527  PMID: 25249858
aryl­imidazole; iron(II); crystal structure
16.  Ethyl 1-acetyl-1H-indole-3-carboxyl­ate 
The title compound, C13H13NO3, was synthesized by acetyl­ation of ethyl 1H-indole-3-carboxyl­ate. The aromatic ring system of the mol­ecule is essentially planar, but the saturated ethyl group is also located within this plane and the overall r.m.s. deviation from planarity is only 0.034 Å. Pairs of C—H⋯O inter­actions connect mol­ecules into chains along the diagonal of the unit cell. Mol­ecules also form weakly connected dimers via π⋯π stacking inter­actions of the indole rings with centroid–centroid separations of 3.571 (1) Å. C—H⋯π inter­actions between methyl­ene and methyl groups and the indole and benzene ring complete the directional inter­molecular inter­actions found in the crystal structure.
PMCID: PMC2977149  PMID: 21583507
17.  4-Hy­droxy-3-meth­oxy­benzaldehyde thio­semicarbazone 
In the title compound, C9H11N3S, there is an intra­molecular O—H⋯O hydrogen bond involving the OH group and the adjacent methoxy O atom. The mol­ecule is essentially planar, with the maximum deviation from the mean plane of the non-H atoms being 0.1127 (14) Å for the methyl C atom. In the crystal, mol­ecules are connected via centrosymmetric pairs of N—H⋯S and O—H⋯O hydrogen bonds into a two-dimensional network parallel to (10-3).
PMCID: PMC3885096  PMID: 24454272
18.  Benzoic acid–2-{(E)-[(E)-2-(2-pyridyl­methyl­idene)hydrazin-1-yl­idene]meth­yl}pyridine (2/1) 
The asymmetric unit of the title cocrystal, C12H10N4·2C7H6O2, comprises a single mol­ecule of benzoic acid and one half-mol­ecule of 2-pyridine­aldazine situated about a centre of inversion. The carboxyl group is coplanar with the benzene ring to which it is connected [O—C—C—C = −172.47 (12)°] and similarly, the 2-pyridine­aldazine mol­ecule is planar (r.m.s. deviation of the 16 non-H atoms = 0.017 Å). In the crystal, mol­ecules are connected into a non-planar three-mol­ecule aggregate [dihedral angle between the benzene and pyridyl ring connected by the hydrogen bond = 61.30 (7)°] with a twisted Z-shape. Layers of 2-pyridine­aldazine mol­ecules in the ab plane are sandwiched by benzoic acid mol­ecules being connected by O—H⋯N and C—H⋯O inter­actions, the latter involving the carbonyl O atom so that each benzoic acid mol­ecule links three different 2-pyridine­aldazine mol­ecules. Inter­digitated layers stack along the c axis.
PMCID: PMC3009141  PMID: 21589004
19.  5,8-Bis[bis­(pyridin-2-yl)amino]-1,3,4,6,7,9,9b-hepta­aza­phenalen-2(1H)-one dimethyl sulfoxide monosolvate dihydrate 
In the asymmetric unit of the title compound, C26H17N13O·C2H6OS·2H2O, there is one independent hepta­zine-based main mol­ecule, one dimethyl sulfoxide mol­ecule and two water mol­ecules as solvents. The tri-s-triazine unit is substituted with two dipyridyl amine moieties and a carbonylic O atom. As indicated by the bond lengths in this acid unit of the hepta­zine derivative [C=O = 1.213 (2) Å, while the adjacent C—N(H) bond = 1.405 (2) Å] it is best described by the keto form. The cyameluric nucleus is close to planar (r.m.s. deviation = 0.061 Å) and the pyridine rings are inclined to its mean plane by dihedral angles varying from 47.47 (5) to 70.22 (5)°. The host and guest mol­ecules are connected via N—H⋯O, O—H⋯O and O—H⋯N hydrogen bonds, forming a four-membered inversion dimer-like arrangement enclosing an R 4 4(24) ring motif. These arrangements stack along [1-10] with a weak π–π inter­action [inter-centroid distance = 3.8721 (12) Å] involving adjacent pyridine rings. There are also C—H⋯N and C—H⋯O hydrogen bonds and C—H⋯π inter­actions present within the host mol­ecule and linking inversion-related mol­ecules, forming a three-dimensional structure.
PMCID: PMC3998556  PMID: 24826156
20.  Bis(5-methyl­pyrazine-2-carboxyl­ato)­diphenyl­tin(IV) 
In the mol­ecule of the title compound, [Sn(C6H5)2(C6H5N2O2)2], two O and one N atoms from the two 5-methyl­pyrazine-2-carboxyl­ate ligands and one C atom of a phenyl group form a distorted square-planar arrangement in the equatorial plane around the Sn atom, while the distorted octa­hedral coordination is completed by an N atom of one of the 5-methyl­pyrazine-2-carboxyl­ate ligands and a C atom of the other phenyl group in the axial positions. In the crystal structure, inter­molecular C—H⋯O hydrogen bonds link the mol­ecules into centrosymmetric dimers.
PMCID: PMC2961826  PMID: 21202741
21.  4-[(E)-(5-tert-Butyl-2-hydroxy­phen­yl)diazen­yl]benzoic acid benzene hemisolvate 
The title benzene hemisolvate, C17H18N2O3·0.5C6H6, features an essentially planar (the r.m.s. deviation of the non-H atoms, excluding methyl-C, is 0.071 Å) diazo mol­ecule with an E conformation about the N=N bond, and a half-mol­ecule of benzene disposed about a centre of inversion. The dihedral angle formed between the benzene rings of the diazo mol­ecule is 7.69 (12)°. In the crystal, centrosymmetrically related dimers associate via the eight-membered carboxylic acid dimer synthon, {⋯HOC(=O)}2, and these are connected into a supra­molecular chain along the b axis via C—H⋯O contacts.
PMCID: PMC2983727  PMID: 21580311
22.  (E)-3-(2-Nitro­phen­yl)-1-{1-phenyl­sulfonyl-2-[(phenyl­sulfon­yl)meth­yl]-1H-indol-3-yl}prop-2-en-1-one 
In the title compound, C30H22N2O7S2, the configuration about the propene C=C bond is E. The indole unit is essentially planar, with a maximum deviation of 0.031 (3) Å. The dihedral angle between the planes of the phenyl rings of the two phenyl­sulfonyl groups is 80.95 (19)°. The central prop-2-ene-1-one group is oriented at a dihedral angle of 44.26 (11)° with respect to the nitro­phenyl ring and at 39.24 (8)° with respect to the indole unit. The S atoms are in a distorted tetra­hedral configuration. In the crystal, mol­ecules are linked into centrosymmetric dimers via pairs of C—H⋯O hydrogen bonds with an R 2 2(24) graph-set motif. The crystal structure is stabilized by further C—H⋯O inter­actions. Short intra­molecular C—H⋯O contacts result in several S(6) rings.
PMCID: PMC3254289  PMID: 22259588
23.  trans-Di­aqua­bis­(pyridazine-3-carboxyl­ato-κ2 N 2,O)copper(II) 
In the title compound, [Cu(C5H3N2O2)2(H2O)2], the CuII ion, located on an inversion center, exhibits an octa­hedral coordination geometry. The equatorial plane is defined by two trans-related N,O-bidentate pyridazine-3-carboxyl­ate ligands and the axial positions are occupied by two water mol­ecules. In the crystal, mol­ecules are connected by O—H⋯O hydrogen bonds between the water mol­ecules and the noncoordinating carboxyl­ate O atoms, forming layers parallel to the bc plane. The layers are stacked along the a axis by further O—H⋯O hydrogen bonds between the water mol­ecules and the coordinating carboxyl­ate O atoms. Weak C—H⋯O hydrogen bonds are also observed between the pyridazine rings and the water mol­ecules and between the pyridazine rings and the non-coordinating carboxyl­ate O atoms.
PMCID: PMC3998405  PMID: 24764943
24.  Crystal structure of catena-poly[[aqua­bis­(4-formyl­benzoato)-κ2 O 1,O 1′;κO 1-zinc]-μ-pyrazine-κ2 N:N′] 
In the compound, [Zn(C8H5O3)2(C4H4N2)(H2O)]n, the pyrazine ligands bridge the ZnII cations, forming polymeric chains running parallel to the b-axis direction. Water–carboxyl­ate O—H⋯O hydrogen bonds link adjacent chains into layers parallel to the bc plane. The layers are linked via weak pyrazine–formyl C—H⋯O and form­yl–carboxyl­ate C—H⋯O hydrogen bonds.
The asymmetric unit of the title polymeric compound, [Zn(C8H5O3)2(C4H4N2)(H2O)]n, contains two mol­ecular units. Each unit comprises two 4-formyl­benzoate (FB) anions, one pyrazine mol­ecule and one coordinating water mol­ecule; the FB anions act either as bidentate or as monodentate ligands. The O atoms of the bidentately coordinating FB anions are disordered over two positions, and they were refined with fixed occupancy ratios of 0.75:0.25 and 0.70:0.30, respectively. In the ordered monodentately coordinating FB anions, the carboxyl­ate groups are twisted away from the attached benzene rings (B and E) by 12.1 (2) and 9.2 (2)°, respectively. In the disordered FB anions, the corresponding angles are 14.1 (1) and 4.0 (2)° for benzene rings A and D, respectively. Benzene rings A and B are oriented at a dihedral angle of 45.7 (1)°, D and E at 23.2 (1)°. Pyrazine ring C makes dihedral angles of 85.6 (1) and 72.7 (1)°, respectively, with benzene rings A and B, and pyrazine ring F makes dihedral angles of 87.0 (1) and 81.3 (1)° with benzene rings D and E, respectively. The pyrazine ligands bridge the ZnII cations, forming polymeric chains running parallel to the b-axis direction. Medium-strength intra­molecular O—H⋯O hydrogen bonds link the water mol­ecules to the carboxyl­ate O atoms. In the crystal, water–carboxyl­ate O—H⋯O hydrogen bonds link adjacent chains into layers parallel to the bc plane. The layers are linked via weak pyrazine–formyl C—H⋯O and form­yl–carboxyl­ate C—H⋯O hydrogen bonds. π–π contacts between the benzene rings, with centroid-to-centroid distances of 3.7765 (16), 3.7905 (15) and 3.8231 (16) Å, may further stabilize the structure. There are also weak C—H⋯π inter­actions present.
PMCID: PMC4438816  PMID: 26029401
crystal structure; zinc; transition metal complexes of benzoic acid derivatives; hydrogen bonding; π–π inter­actions; C—H⋯π inter­actions
25.  Crystal structure of 2-hy­droxy­imino-2-(pyridin-2-yl)-N′-[1-(pyridin-2-yl)ethyl­idene]acetohydrazide 
The mol­ecule of the title compound is approximately planar with the planes of the two pyridine rings inclined to one another by 5.51 (7)°. In the crystal, mol­ecules are linked by bifurcated O—H⋯(O,N) hydrogen bonds, forming inversion dimers, which are in turn linked via C—H⋯O and C—H⋯N hydrogen bonds, forming sheets lying parallel to (502).
The mol­ecule of the title compound, C14H13N5O2, is approximately planar (r.m.s deviation for all non-H atoms = 0.093 Å), with the planes of the two pyridine rings inclined to one another by 5.51 (7)°. The oxime group is syn to the amide group, probably due to the formation of an intra­molecular N—H⋯N hydrogen bond that forms an S(6) ring motif. In the crystal, mol­ecules are linked by pairs of bifurcated O—H⋯(O,N) hydrogen bonds, forming inversion dimers. The latter are linked via C—H⋯O and C—H⋯N hydrogen bonds, forming sheets lying parallel to (502). The sheets are linked via π–π stacking inter­actions [inter-centroid distance = 3.7588 (9) Å], involving the pyridine rings of inversion-related mol­ecules, forming a three-dimensional structure.
PMCID: PMC4257442  PMID: 25552998
crystal structure; hy­droxy­imino; acetohydrazide; pyridyl­ethyl­idene; hydrogen bonding; π–π stacking inter­actions

Results 1-25 (1302446)