Formation of 1-(thia-zol-2-yl)-4,5-di-hydropyrazoles from simple precursors: synthesis, spectroscopic characterization and the structures of an inter-mediate and two products.

Two new 1-(thia-zol-2-yl)-4,5-di-hydropyrazoles have been synthesized from simple precursors, and characterized both spectroscopically and structurally. In addition, two inter-mediates in the reaction pathway have been isolated and characterized, one of them structurally. The mol-ecules of the inter-mediate (E)-1-(4-meth-oxy-phen-yl)-3-[4-(prop-2-yn-yloxy)phen-yl]prop-2-en-1-one, C19H16O3 (I), are linked by a combination of C-H⋯O and C-H⋯π(arene) hydrogen bonds to form ribbons. The products (RS)-5-(4-meth-oxy-phen-yl)-1-(4-phenythiazol-2-yl)-3-[4-(prop-2-yn--yloxy)phen-yl]-4,5-di-hydro-1H-pyrazole, C28H23N3O2S (II), and (RS)-5-(4-meth-oxy-phen-yl)-1-[4-(4-methyl-phen-yl)thia-zol-2-yl]-3-[4-(prop-2-yn-yloxy)phen-yl]-4,5-di-hydro-1H-pyrazole, C29H25N3O2S (III), are closely related - differing only by presence or absence of a methyl group at the aryl-thia-zolyl substituent - and crystallize in an isomorphous setting. Both mol-ecules contain an effectively planar di-hydro-pyrazole ring, and possess an overall T-shaped structure, which is a characteristic of triaryl-substituted 4,5-di-hydro-1-(thia-zol-2-yl)pyrazole compounds. The crystal packing is characterized by inter-molecular C-H⋯S and C-H⋯π (ar-yl/alkyne) inter-actions. A combination of two C-H⋯π(arene) hydrogen bonds links the product mol-ecules into sheets.

Fifteen 4-(2-meth-oxy-phen-yl)piperazin-1-ium salts containing organic anions: supra-molecular assembly in zero, one, two and three dimensions.

Fifteen 4-(2-meth-oxy-phen-yl)piperazin-1-ium salts containing organic anions have been prepared and structurally characterized. In the isostructural 4-chloro-benzoate and 4-bromo-benzoate salts, C11H17N2O+·C7H4ClO2 - (I) and C11H17N2O+·C7H4BrO2 - (II), and the 4-iodo-benzoate salt C11H17N2O+·C7H4IO2 - (III), the ions are linked by N-H⋯O hydrogen bonds, forming centrosymmetric R 4 4(12) four-ion aggregates; a similar aggregate is formed in the 2-chloro-benzoate salt (V), isomeric with (I). In the 2-fluoro-benzoate salt C11H17N2O+·C7H4FO2 - (IV), and the isomorphous pair of salts, the 2-bromo-benzoate (VI), isomeric with (II) and 2-iodo-benzoate (VII), isomeric with (III), N-H⋯O and C-H⋯π(arene) interactions link the components into three-dimensional arrays. Four-ion R 4 4(12) aggregates are also found in the 2-methyl-benzoate, 4-amino-benzoate and 4-nitro-benzoate salts, C11H17N2O+·C8H7O2 - (VIII), C11H17N2O+·C7H6NO2 - (IX) and C11H17N2O+·C7H4NO4 - (X), but those in (IX) are linked into complex sheets by an additional N-H⋯O hydrogen bond. In the 3,5-dinitrobenzoate salt, C11H17N2O+·C7H3N2O6 -·2H2O (XI), N-H⋯O and O-H⋯O hydrogen bonds link the components into a complex ribbon structure. In the picrate salt, C11H17N2O+·C6H2N3O7 - (XII), the four-ion aggregates are linked into chains of rings by C-H⋯O hydrogen bonds. In the hydrogen maleate salt, C11H17N2O+·C4H3O4 - (XIII), two- and three-centre hydrogen bonds link the ions into a ribbon structure while both anions contain very short but asymmetric O-H⋯O hydrogen bonds, having O⋯O distances of 2.4447 (16) and 2.4707 (17) Å. O-H⋯O Hydrogen bonds link the anions in the hydrogen fumarate salt (XIV), isomeric with (XIII), into chains that are linked into sheets via N-H⋯O hydrogen bonds. In the hydrogen (2R,3R)-tartrate salt, C11H17N2O+·C4H5O6 -·1.698H2O (XV), the anions are linked into sheets by O-H⋯O hydrogen bonds. Comparisons are made with the structures of some related compounds.

Functionalized 3-(5-ar-yloxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)-1-(4-substituted-phen-yl)prop-2-en-1-ones: synthetic pathway, and the structures of six examples.

Five examples each of 3-(5-ar-yloxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)-1-[4-(prop-2-yn-1-yl-oxy)phen-yl]prop-2-en-1-ones and the corresponding 1-(4-azido-phen-yl)-3-(5-ar-yloxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)prop-2-en-1-ones have been synthesized in a highly efficient manner, starting from a common source precursor, and structures have been determined for three examples of each type. In each of 3-[5-(2-chloro-phen-oxy)-3-methyl-1-phenyl-1H-pyrazol-4-yl]-1-[4-(prop-2-yn-1-yl-oxy)phen-yl]prop-2-en-1-one, C28H21ClN2O3, (Ib), the isomeric 3-[5-(2-chloro-phen-oxy)-3-methyl-1-phenyl-1H-pyrazol-4-yl]-1-[4-(prop-2-yn-1-yl-oxy)phen-yl]prop-2-en-1-one, (Ic), and 3-[3-methyl-5-(naphthalen-2-yl-oxy)-1-phenyl-1H-pyrazol-4-yl]-1-[4-(prop-2-yn-yloxy)phen-yl]prop-2-en-1-one, C32H24N2O3, (Ie), the mol-ecules are linked into chains of rings, formed by two independent C-H⋯O hydrogen bonds in (Ib) and by a combination of C-H⋯O and C-H⋯π(arene) hydrogen bonds in each of (Ic) and (Ie). There are no direction-specific inter-molecular inter-actions in the structure of 1-(4-azido-phen-yl)-3-[3-methyl-5-(2-methyl-phen-oxy)-1-phenyl-1H-pyrazol-4-yl]prop-2-en-1-one, C26H21N5O2, (IIa). In 1-(4-azido-phen-yl)-3-[5-(2,4-di-chloro-phen-oxy)-3-methyl-1-phenyl-1H-pyrazol-4-yl]prop-2-en-1-one, C25H17Cl2N5O2, (IId), the di-chloro-phenyl group is disordered over two sets of atomic sites having occupancies 0.55 (4) and 0.45 (4), and the mol-ecules are linked by a single C-H⋯O hydrogen bond to form cyclic, centrosymmetric R 2 2(20) dimers. Similar dimers are formed in 1-(4-azido-phen-yl)-3-[3-methyl-5-(naphthalen-2-yl-oxy)-1-phenyl-1H-pyrazol-4-yl]prop-2-en-1-one, C29H21N5O2, (IIe), but here the dimers are linked into a chain of rings by two independent C-H..π(arene) hydrogen bonds. Comparisons are made between the mol-ecular conformations within both series of compounds.

Conversion of di-aryl-chalcones into 4,5-di-hydro-pyrazole-1-carbo-thio-amides: mol-ecular and supra-molecular structures of two precursors and three products.

Chalcones of type 4-XC6H4C(O)CH=CHC6H4(OCH2CCH)-4, where X = Cl, Br or MeO, have been converted to the corresponding 4,5-di-hydro-pyrazole-1-carbo-thio-amides using a cyclo-condensation reaction with thio-semicarbazide. The chalcones 1-(4-chloro-phen-yl)-3-[4-(prop-2-yn-yloxy)phen-yl]prop-2-en-1-one, C18H13ClO2, (I), and 1-(4-bromo-phen-yl)-3-[4-(prop-2-yn-yloxy)phen-yl]prop-2-en-1-one, C18H13BrO2, (II), are isomorphous, and their mol-ecules are linked into sheets by two independent C-H⋯π(arene) inter-actions, both involving the same aryl ring with one C-H donor approaching each face. In each of the products (RS)-3-(4-chloro-phen-yl)-5-[4-(prop-2-yn-yloxy)phen-yl]-4,5-di-hydro-pyrazole-1-carbo-thio-amide, C19H16ClN3OS, (IV), (RS)-3-(4-bromo-phen-yl)-5-[4-(prop-2-yn-yloxy)phen-yl]-4,5-di-hydro-pyrazole-1-carbo-thio-amide, C19H16BrN3OS, (V), and (RS)-3-(4-meth-oxy-phen-yl)-5-[4-(prop-2-yn-yloxy)phen-yl]-4,5-di-hydro-pyrazole-1-carbo-thio-amide, C20H19N3O2S, (VI), the reduced pyrazole ring adopts an envelope conformation with the C atom bearing the 4-prop-2-yn-yloxy)phenyl substituent, which occupies the axial site, displaced from the plane of the four ring atoms. Compounds (IV) and (V) are isomorphous and their mol-ecules are linked into chains of edge-fused rings by a combination of N-H⋯S and C-H⋯S hydrogen bonds. The mol-ecules of (VI) are linked into sheets by a combination of N-H⋯S, N-H⋯N and C-H⋯π(arene) hydrogen bonds. Comparisons are made with the structures of some related compounds.

Two isostructural 3-(5-ar-yloxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)-1-(thio-phen-2-yl)prop-2-en-1-ones: disorder and supra-molecular assembly.

Two new chalcones containing both pyrazole and thio-phene substituents have been prepared and structurally characterized. 3-(3-Methyl-5-phen-oxy-1-phenyl-1H-pyrazol-4-yl)-1-(thio-phen-2-yl)prop-2-en-1-one, C23H18N2O2S (I), and 3-[3-methyl-5-(2-methyl-phen-oxy)-1-phenyl-1H-pyrazol-4-yl]-1-(thio-phen-2-yl)prop-2-en-1-one, C24H20N2O2S (II), are isomorphous as well as isostructural, and in each the thio-phene substituent is disordered over two sets of atomic sites having occupancies 0.844 (3) and 0.156 (3) in (I), and 0.883 (2) and 0.117 (2) in (II). In each structure, the mol-ecules are linked into sheets by a combination of C-H⋯N and C-H⋯O hydrogen bonds. Comparisons are made with some related compounds.

Conversion of substituted 5-aryloxypyrazolecarbaldehydes into reduced 3,4'-bipyrazoles: synthesis and characterization, and the structures of four precursors and two products, and their supramolecular assembly in zero, one and two dimensions.

The reaction of 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde with phenols under basic conditions yields the corresponding 5-aryloxy derivatives; the subsequent reaction of these carbaldehydes with substituted acetophenones yields the corresponding chalcones, which in turn undergo cyclocondensation reactions with hydrazine in the presence of acetic acid to form N-acetylated reduced bipyrazoles. Structures are reported for three 5-aryloxycarbaldehydes and the 5-piperidino analogue, and for two reduced bipyrazole products. 5-(2-Chlorophenoxy)-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde, C17H13ClN2O2, (II), which crystallizes with Z' = 2 in the space group P-1, exhibits orientational disorder of the carbaldehyde group in each of the two independent molecules. Each of 3-methyl-5-(4-nitrophenoxy)-1-phenyl-1H-pyrazole-4-carbaldehyde, C17H13N3O4, (IV), 3-methyl-5-(naphthalen-2-yloxy)-1-phenyl-1H-pyrazole-4-carbaldehyde, C21H16N2O2, (V), and 3-methyl-1-phenyl-5-(piperidin-1-yl)-1H-pyrazole-4-carbaldehyde, C16H19N3O, (VI), (3RS)-2-acetyl-5-(4-azidophenyl)-5'-(2-chlorophenoxy)-3'-methyl-1'-phenyl-3,4-dihydro-1'H,2H-[3,4'-bipyrazole] C27H22ClN7O2, (IX) and (3RS)-2-acetyl-5-(4-azidophenyl)-3'-methyl-5'-(naphthalen-2-yloxy)-1'-phenyl-3,4-dihydro-1'H,2H-[3,4'-bipyrazole] C31H25N7O2, (X), has Z' = 1, and each is fully ordered. The new compounds have all been fully characterized by analysis, namely IR spectroscopy, 1H and 13C NMR spectroscopy, and mass spectrometry. In each of (II), (V) and (IX), the molecules are linked into ribbons, generated respectively by combinations of C-H...N, C-H...π and C-Cl...π interactions in (II), C-H...O and C-H...π hydrogen bonds in (V), and C-H...N and C-H...O hydrogen bonds in (IX). The molecules of compounds (IV) and (IX) are both linked into sheets, by multiple C-H...O and C-H...π hydrogen bonds in (IV), and by two C-H...π hydrogen bonds in (IX). A single C-H...N hydrogen bond links the molecules of (X) into centrosymmetric dimers. Comparisons are made with the structures of some related compounds.

Co-crystallization of 3,5-di-nitro-benzoic acid with two anti-psychotic agents: a simple 1:1 salt with trihexyphenidyl and a 1:2 acid salt containing a very short O-H⋯O hydrogen bond with chlorprothixene.

Co-crystallization of racemic 1-cyclo-hexyl-1-phenyl-3-(piperidin-1-yl)propan-1-ol (trihexyphenid-yl) with 3,5-di-nitro-benzoic acid gives a simple 1:1 salt, namely 1-(3-cyclo-hexyl-3-hy-droxy-3-phenyl-prop-yl)piperidin-1-ium 3,5-di-nitro-benzoate, C20H32NO+·C7H3N2O6 -, (I), whereas a similar co-crystallization using (Z)-3-(2-chloro-9H-thioxanthen-9-yl)-N,N-di-methyl-propan-1-amine (chlorprothixene) gives a 1:2 acid salt, namely (Z)-3-(2-chloro-9H-thioxanthen-9-yl)-N,N-di-methyl-propan-1-aminium hydrogen bis-(3,5-di-nitro-benzoate), C18H19ClNS+·[H(C7H3N2O6)2]-, (II), the anion of which contains a very short O-H⋯O hydrogen bond, with dimensions O-H = 1.04 (3) Å, H⋯O = 1.41 (3) Å, O⋯O = 2.4197 (15) Šand O-H⋯O = 161 (3)°. In the cation of (I), the cyclo-hexyl and piperidyl rings both adopt chair conformations, whereas in the cation of (II), the central heterocyclic ring adopts a boat conformation, so that the dihedral angle between the two aryl rings is 41.56 (4)°. A combination of O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds links the ions of (I) into a complex chain of rings, and these chains are linked into sheets by π-π stacking inter-actions between inversion-related pairs of anions. In compound (II), a different combination of O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds links the ions into sheets. Comparisons are made with some related structures.

Four 1-aryl-1H-pyrazole-3,4-di-carboxyl-ate derivatives: synthesis, mol-ecular conformation and hydrogen bonding.

Four 1-aryl-1H-pyrazole-3,4-di-carboxyl-ate derivatives, one acid, two esters and a dicarbohydrazide have been synthesized starting from 3-aryl sydnones, and structurally characterized. There is an intra-molecular O-H⋯O hydrogen bond in 1-phenyl-1H-pyrazole-3,4-di-carb-oxy-lic acid, C11H8N2O4, (I), and the mol-ecules are linked into a three-dimensional framework structure by a combination of O-H⋯O, O-H⋯N, C-H⋯O and C-H⋯π(arene) hydrogen bonds. In each of the two esters dimethyl 1-phenyl-1H-pyrazole-3,4-di-carboxyl-ate, C13H12N2O4, (II), and dimethyl 1-(4-methyl-phen-yl)-1H-pyrazole-3,4-di-carboxyl-ate, C14H14N2O4, (III), C-H⋯O hydrogen bonds lead to the formation of cyclic centrosymmetric dimers: in (III), one of the meth-oxy-carbonyl groups is disordered over two sets of atomic sites having occupancies 0.71 (2) and 0.29 (2). An intra-molecular N-H⋯O hydrogen bond is present in the structure of 1-(4-meth-oxy-phen-yl)-1H-pyrazole-3,4-dicarbohydrazide, C12H14N6O3, (IV), and the mol-ecules are linked into a three-dimensional framework structure by a combination of N-H⋯O, N-H⋯N, N-H⋯π(arene) and C-H⋯O hydrogen bonds. Comparisons are made with the structures of a number of related compounds.

Eight Schiff bases derived from various salicylaldehydes: phenol-imine and keto-amine forms, conformational disorder, and supramolecular assembly in one and two dimensions.

Structures are reported for eight Schiff bases derived from various salicylaldehydes: five are newly synthesized and re-investigations are reported for three previously reported structures, leading, in each case, to some revision of previous conclusions. In (E)-N-(3,4-dimethylisoxazol-5-yl)-4-[(2-hydroxybenzylidene)amino]benzenesulfonamide, C18H17N3O4S, (I), and (E)-4-[(5-bromo-2-hydroxy-3-methoxybenzylidene)amino]-N-(3,4-dimethylisoxazol-5-yl)benzenesulfonamide. C19H18BrN3O5S, (II), the isoxazole rings adopt different orientations relative to the rest of the molecules, despite the additional substituents in (II) being in the aryl ring remote from the isoxazole unit. The molecules of both (E)-4-bromo-2-[(2-hydroxyphenylimino)methyl]-6-methoxyphenol, C14H12BrNO3, (III), and (E)-4-bromo-2-methoxy-6-[(2-methoxyphenylimino)methyl]phenol, C15H14BrNO3, (IV), are both effectively planar; while (III) adopts the phenol-imine constitution, (IV) adopts the keto-amine constitution. (E)-2-Methoxy-6-[(2-methoxyphenylimino)methyl]phenol, C15H15NO3, (V), which was determined previously using powder X-ray data assuming the phenol-imine constitution, has now been refined from single-crystal X-ray data, confirming the phenol-imine constitution. In (E)-3-benzoyl-2-[(5-fluoro-2-hydroxybenzylidene)amino]-4,5,6,7-tetrahydrobenzo[b]thiophene, C22H18FNO2S, (VI), the fused carbocyclic ring exhibits conformational disorder; both disorder components, having populations of 0.705 (4) and 0.295 (4), adopt half-chair conformations. The isostructural (E)-3-benzoyl-2-[(2-hydroxybenzylidene)amino)]-4,5,6,7-tetrahydrobenzo[b]thiophene, C22H19NO2S, (VII), which was originally reported as having a fully ordered structure [Kaur et al. (2014). Acta Cryst. E70, o476-o477], has been rerefined using the original data set and found to exhibit the same type of disorder as found in (VI), with disordered populations having occupancies of 0.851 (3) and 0.149 (3). The triclinic polymorph of (E)-[(2-hydroxyphenylimino)methyl]phenol, C13H11NO2, (VIII), which crystallizes with Z' = 2 in the space group P-1, has been described variously as occurring as the keto-amine tautomer [Maciejewska et al. (1999). J. Phys. Org. Chem. 12, 875-880] and as the phenol-imine tautomer [Tunç et al. (2009). J. Chem. Crystallogr. 39, 672-676]. Rerefinement of this structure using one of the original data sets shows that both of the independent molecules exist in the keto-amine form. In the structures of compounds (I), (VI), (VII) and (VIII), hydrogen bonds generate simple chains, while a chain of rings is formed in (V). Sheets are formed by hydrogen bonds in both (II) and (III), while in (IV), the sheet structure is built from aromatic π-π stacking interactions.

The crystal structure of (E)-2-ethyl-N-(4-nitro-benzyl-idene)aniline: three-dimensional supra-molecular assembly mediated by C-H⋯O hydrogen bonds and nitro⋯π(arene) inter-actions.

In the mol-ecule of the title compound, C15H14N2O2, the 2-ethyl-phenyl group is disordered over two sets of atomic sites having occupancies of 0.515 (19) and 0.485 (19), and the dihedral angle between the two partial-occupancy aryl rings is 6(2)°. A combination of C-H⋯O hydrogen bonds and nitro⋯π(arene) inter-actions links the mol-ecules into a continuous three-dimensional framework structure. Comparisons are made with the structures of some related compounds.

Reinvestigation of the crystal structure of N-(4-chloro-benzyl-idene)-2-hy-droxy-aniline: a three-dimensional structure containing O-H⋯N, O-H⋯O and C-H⋯π(arene) hydrogen bonds.

The mol-ecule of the title compound, C13H10ClNO, (I), which contains an intra-molecular O-H⋯N hydrogen bond, is almost planar: the dihedral angle between the two aryl rings is only 3.31 (9)°. The mol-ecules of (I) are linked into sheets by two C-H⋯π(arene) hydrogen bonds and the sheets are linked into a three-dimensional structure by O-H⋯O hydrogen bonds. Comparisons are made with the structures of a number of related compounds.

Synthesis and structures of six closely related N-[3-(2-chlorobenzoyl)-5-ethylthiophen-2-yl]arylamides, together with an isolated reaction intermediate: order versus disorder, molecular conformations and hydrogen bonding in zero, one and two dimensions.

Six closely related N-[3-(2-chlorobenzoyl)-5-ethylthiophen-2-yl]arylamides have been synthesized and structurally characterized, together with a representative reaction intermediate. In each of N-[3-(2-chlorobenzoyl)-5-ethylthiophen-2-yl]benzamide, C20H16ClNO2S, (I), N-[3-(2-chlorobenzoyl)-5-ethylthiophen-2-yl]-4-phenylbenzamide, C26H20ClNO2S, (II), and 2-bromo-N-[3-(2-chlorobenzoyl)-5-ethylthiophen-2-yl]benzamide, C20H15BrClNO2S, (III), the molecules are disordered over two sets of atomic sites, with occupancies of 0.894 (8) and 0.106 (8) in (I), 0.832 (5) and 0.168 (5) in (II), and 0.7006 (12) and 0.2994 (12) in (III). In each of N-[3-(2-chlorobenzoyl)-5-ethylthiophen-2-yl]-2-iodobenzamide, C20H15ClINO2S, (IV), and N-[3-(2-chlorobenzoyl)-5-ethylthiophen-2-yl]-2-methoxybenzamide, C21H18ClNO3S, (V), the molecules are fully ordered, but in N-[3-(2-chlorobenzoyl)-5-ethylthiophen-2-yl]-2,6-difluorobenzamide, C20H14ClF2NO2S, (VI), which crystallizes with Z' = 2 in the space group C2/c, one of the two independent molecules is fully ordered, while the other is disordered over two sets of atomic sites having occupancies of 0.916 (3) and 0.084 (3). All of the molecules in compounds (I)-(VI) exhibit an intramolecular N-H...O hydrogen bond. The molecules of (I) and (VI) are linked by C-H...O hydrogen bonds to form finite zero-dimensional dimers, which are cyclic in (I) and acyclic in (VI), those of (III) are linked by C-H...π(arene) hydrogen bonds to form simple chains, and those of (IV) and (V) are linked into different types of chains of rings, built in each case from a combination of C-H...O and C-H...π(arene) hydrogen bonds. Two C-H...O hydrogen bonds link the molecules of (II) into sheets containing three types of ring. In benzotriazol-1-yl 3,4-dimethoxybenzoate, C15H13N3O4, (VII), the benzoate component is planar and makes a dihedral angle of 84.51 (6)° with the benzotriazole unit. Comparisons are made with related compounds.

Four closely related N-(3-benzoyl-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)benzamides: order versus disorder, and similar molecular conformations but different modes of supramolecular aggregation, with a new disordered refinement of 2-amino-3-benzoyl-4,5,6,7-tetrahydrobenzo[b]thiophene.

Four closely related N-(3-benzoyl-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)benzamides, bearing different substituents on the benzamide ring, have been synthesized and structurally characterized. In each of N-(3-benzoyl-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)-3-fluorobenzamide, C22H18FNO2S, (I), N-(3-benzoyl-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)-4-chlorobenzamide, C22H18ClNO2S, (II), N-(3-benzoyl-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)-2,6-difluorobenzamide, C22H17F2NO2S, (III), and N-(3-benzoyl-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)-2-methoxybenzamide, C23H21NO3S, (IV), the last of which crystallizes with Z' = 2 in the space group P-1, the fused six-membered ring adopts a half-chair conformation. In each of (I)-(III), this ring is disordered over two sets of atomic sites having occupancies of 0.811 (6) and 0.189 (6) in (I), 0.645 (7) and 0.355 (7) in (II), and 0.784 (6) and 0.216 (6) in (III), such that the two disorder components of the ring are almost enantiomeric. Molecules of (I) are linked into chains by π-π stacking interactions, and those of (II) are linked into chains by a C-H...π hydrogen bond. A combination of two C-H...O hydrogen bonds and two C-H...π hydrogen bonds links the molecules of (III) into complex sheets, but the molecules of (IV) are linked by a combination of two hydrogen bonds, one each of the C-H...O and C-H...π types, to form centrosymmetric tetramers. The structures of (I)-(IV) are compared with that of the unsubstituted analogue N-(3-benzoyl-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)benzamide and a new refinement of the parent amine 2-amino-3-benzoyl-4,5,6,7-tetrahydrobenzo[b]thiophene, using the original data set, has found that here too the fused six-membered ring exhibits conformational disorder, with occupancies of 0.887 (9) and 0.113 (9). Comparisons are made with some related compounds.

Crystal structures of (E)-1-{3-[(5-fluoro-2-hy-droxy-benzyl-idene)amino]-phen-yl}ethanone and of a fourth polymorph of (E)-1-{3-[(2-hy-droxy-3-meth-oxy-benzyl-idene)amino]-phen-yl}ethanone.

In the mol-ecules of both (E)-1-{3-[(5-fluoro-2-hy-droxy-benzyl-idene)amino]-phen-yl}ethanone, C15H12FNO2, (I), and (E)-1-{3-[(2-hy-droxy-3-meth-oxy-benzyl-idene)amino]-phen-yl}ethanone, C16H15NO3, (II), which crystallizes with Z' = 2 in space group Pca21, there are intra-molecular O-H⋯N hydrogen bonds, and the non-H atoms in each mol-ecule are essentially coplanar. In the crystal of (I), mol-ecules are linked by a single C-H⋯O hydrogen bond to form a C(8) chain, whereas in the crystal of (II), mol-ecules are linked by three C-H⋯O hydrogen bonds to form sheets within which orthogonal C22(16) and C22(17) chains can be identified. Comparisons are made with some related structures.

Crystal structures of 2-amino-4,4,7,7-tetra-methyl-4,5,6,7-tetra-hydro-1,3-benzo-thia-zol-3-ium benzoate and 2-amino-4,4,7,7-tetra-methyl-4,5,6,7-tetra-hydro-1,3-benzo-thia-zol-3-ium picrate.

In both 2-amino-4,4,7,7-tetra-methyl-4,5,6,7-tetra-hydro-1,3- benzo-thia-zol-3-ium benzoate, C11H19N2S+·C7H5O2-, (I), and 2-amino-4,4,7,7-tetra-methyl-4,5,6,7-tetra-hydro-1,3-benzo-thia-zol-3-ium picrate (2,4,6-tri-nitro-phenolate), C11H19N2S+·C6H2N3O7-, (II), the cations are conformationally chiral as the six-membered rings adopt half-chair conformations, which are disordered over two sets of atomic sites giving approximately enanti-omeric disorder. For both cations, the bond lengths indicate delocalization of the positive charge comparable to that in an amidinium cation. The bond lengths in the picrate anion in (II) are consistent with extensive delocalization of the negative charge into the ring and onto the nitro groups, in two of which the O atoms are disordered over two sets of sites. In (I), the ionic components are linked by N-H⋯O hydrogen bonds to form a chain of rings, and in (II), the N-H⋯O hydrogen bonds link the components into centrosymmetric four-ion aggregates containing seven hydrogen bonded rings of four different types.

Three closely related 4,5,6,7-tetrahydro-1H-pyrazolo[4,3-c]pyridines: synthesis, molecular conformations and hydrogen bonding in zero, one and two dimensions.

In each of 1-(4-fluorophenyl)-5-methylsulfonyl-3-[4-(trifluoromethyl)phenyl]-4,5,6,7-tetrahydro-1H-pyrazolo[4,3-c]pyridine, C21H19F4N3O2S, (I), 1-(4-chlorophenyl)-5-methylsulfonyl-3-[4-(trifluoromethyl)phenyl]-4,5,6,7-tetrahydro-1H-pyrazolo[4,3-c]pyridine, C21H19ClF3N3O2S, (II), and 1-(3-methylphenyl)-5-methylsulfonyl-3-[4-(trifluoromethyl)phenyl]-4,5,6,7-tetrahydro-1H-pyrazolo[4,3-c]pyridine, C22H22F3N3O2S, (III), the reduced pyridine ring adopts a half-chair conformation with the methylsulfonyl substituent occupying an equatorial site. Although compounds (I) and (II) are not isostructural, having the space groups Pbca and P212121, respectively, their molecular conformations are very similar, but the conformation of compound (III) differs from those of (I) and (II) in the relative orientation of the N-benzyl and methylsulfonyl substituents. In compounds (II) and (III), but not in (I), the trifluoromethyl groups are disordered over two sets of atomic sites. Molecules of (I) are linked into centrosymmetric dimers by C-H...π(arene) hydrogen bonds, molecules of (II) are linked by two C-H...O hydrogen bonds to form ribbons of R33(18) rings, which are themselves further linked by a C-Cl...π(arene) interaction, and a combination of C-H...O and C-H...π(arene) hydrogen bonds links the molecules of (III) into sheets. Comparisons are made with the structures of some related compounds.

Three closely related 1-(naphthalen-2-yl)prop-2-en-1-ones: pseudosymmetry, disorder and supramoleular assembly mediated by C-H...π and C-Br...π interactions.

It has been observed that when electron-rich naphthyl rings are present in chalcones they can participate in π-π stacking interactions, and this can play an important role in orientating inhibitors within the active sites of enzymes, while chalcones containing heterocyclic substituents additionally exhibit fungistatic and fungicidal properties. With these considerations in mind, three new chalcones containing 2-naphthyl substituents were prepared. 3-(4-Fluorophenyl)-1-(naphthalen-2-yl)prop-2-en-1-one, C19H13FO, (I), crystallizes with Z' = 2 in the space group P-1 and the four molecules in the unit cell adopt an arrangement which resembles that in the space group P21/a. Although 3-(4-bromophenyl)-1-(naphthalen-2-yl)prop-2-en-1-one, C19H13BrO, (II), with Z' = 1, is not isostructural with (I), the molecules of (I) and (II) adopt very similar conformations. In 1-(naphthalen-2-yl)-3-(thiophen-2-yl)prop-2-en-1-one, C17H12OS, (III), the thiophene unit is disordered over two sets of atomic sites, with occupancies of 0.780 (3) and 0.220 (3), which are related by a near 180° rotation of the thiophene unit about its exocyclic C-C bond. The molecules of compound (I) are linked by three independent C-H...π(arene) hydrogen bonds to form centrosymmetric octamolecular aggregates, whereas the molecules of compound (II) are linked into molecular ladders by a combination of C-H...π(arene) and C-Br...π(arene) interactions, and those of compound (III) are linked into centrosymmetric dimers by C-H...π(thiophene) interactions.

Different molecular conformations co-exist in each of three 2-aryl-N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)acetamides: hydrogen bonding in zero, one and two dimensions.

4-Antipyrine [4-amino-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one] and its derivatives exhibit a range of biological activities, including analgesic, antibacterial and anti-inflammatory, and new examples are always of potential interest and value. 2-(4-Chlorophenyl)-N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)acetamide, C19H18ClN3O2, (I), crystallizes with Z' = 2 in the space group P\overline{1}, whereas its positional isomer 2-(2-chlorophenyl)-N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)acetamide, (II), crystallizes with Z' = 1 in the space group C2/c; the molecules of (II) are disordered over two sets of atomic sites having occupancies of 0.6020 (18) and 0.3980 (18). The two independent molecules of (I) adopt different molecular conformations, as do the two disorder components in (II), where the 2-chlorophenyl substituents adopt different orientations. The molecules of (I) are linked by a combination of N-H...O and C-H...O hydrogen bonds to form centrosymmetric four-molecule aggregates, while those of (II) are linked by the same types of hydrogen bonds forming sheets. The related compound N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-2-(3-methoxyphenyl)acetamide, C20H21N3O3, (III), is isomorphous with (I) but not strictly isostructural; again the two independent molecules adopt different molecular conformations, and the molecules are linked by N-H...O and C-H...O hydrogen bonds to form ribbons. Comparisons are made with some related structures, indicating that a hydrogen-bonded R2(2)(10) ring is the common structural motif.

Crystal structure of 2-benzoyl-amino-N'-(4-hy-droxy-benzyl-idene)-3-(thio-phen-2-yl)prop-2-eno-hydrazide.

In the title compound, C21H17N3O3S, the non-H atoms, apart from those in the benzoyl group, are almost coplanar (r.m.s. deviation = 0.049 Å) and the benzoyl group is almost orthogonal to the plane of the rest of the mol-ecule [dihedral angle = 80.34 (6)°]. In the crystal, a combination of N-H⋯O and asymmetric bifurcated O-H⋯(N,O) hydrogen bonds link the mol-ecules into a three-dimensional network. Weak C-H⋯O inter-actions are also observed.

Tuning the Electronic Properties of 2-Cyano-3-phenylacrylamide Derivatives.

We are the first to report the synthesis of a new class of 2-cyanoarylacrylamide (2-CAA) derivatives and observe that the synthesized 2-CAA shows fluorescence properties due to the formation of a dimeric interaction of hydrogen bonds between carbonyl oxygens and amide hydrogens (C═O···H-N-C═O···H-N···); i.e., dimers are linked through dimeric N-H···O hydrogen bonds. The single-crystal X-ray structure shows molecules to be hydrogen-bonded dimers, which further form a parallel stacking arrangement, mediated by significant π-π interactions. The (1)H NMR and fluorescence spectral studies indicate the coexistence of amide and iminol tautomers in solution, which can be influenced by the nature of the solvent. Further, the excitation-wavelength-dependent fluorescence spectrum and the biexponential fluorescence decay profiles suggest the presence of more than one emitting species; i.e., amide and iminol tautomers coexists in solution. We have also shown that the equilibrium between the two tautomers can be tuned by the judicious choice of electron-donating or -withdrawing substituents.