Acta Crystallographica Section C

A non-twinned polymorph of CaTe2O5 from a hydrothermally grown crystal

Weil, M. — 2008-08-09

In contrast with the multiple twinning and/or domain formation found in the mica-like polymorphs of CaTe2O5, calcium pentaoxidoditellurate(IV), that have been prepared by solid-state reactions and for which complete structure determinations have not been successful up to now, the crystal structure of a hydrothermally grown phase was fully determined from a non-twinned crystal. The structure is made up of alternating layers of Ca2+ cations and of 2∞[Te2O5]2− anions stacked along [100]. The lone-pair electrons E of the TeIV atoms are stereochemically active and protrude into channels within the anionic layer. In comparison with analogous MIITe2O5 structures (M = Mg, Mn, Ni or Cu) with ditellurate(IV) anions that are exclusively made up of corner-sharing TeOx (x = 3–5) polyhedra resulting in flat 2∞[Te2O5]2− layers, the anionic layers in CaTe2O5 are undulating and are built of corner- and edge-sharing [TeO4] polyhedra.

Sr, Ba and Cd arsenates with the apatite-type structure

Đordević, T. — 2008-08-09

X-ray diffraction analysis of single crystals of three new arsenates adopting apatite-type structures yielded formula Sr5(AsO4)3F for strontium arsenate fluoride, (I), (Sr1.66Ba0.34)(Ba2.61Sr0.39)(AsO4)3Cl for strontium barium arsenate chloride, (II), and Cd5(AsO4)3Cl0.58(OH)0.42 for cadmium arsenate hydroxide chloride, (III). All three structures are built up of isolated slightly distorted AsO4 tetrahedra that are bridged by Sr2+ in (I), by Sr2+/Ba2+ in (II) and by Cd2+ in (III). Compounds (I) and (II) represent typical fluorapatites and chlorapatites, respectively, with F− at the 2a (0, 0, {1 \over 4}) site and Cl− at the 2b (0, 0, 0) site of P63/m. In contrast, in (III), due to the requirement that the smaller Cd2+ cation is positioned closer to the channel Cl− anion (partially substituted by OH−), the anion occupies the unusual 2a (0, 0, {1 \over 4}) site. Therefore, Cl− is similar to F− in (I), coordinated by three A2 cations, unlike the octahedrally coordinated Cl− in (II) and other ordinary chlorapatites. Furthermore, in (III), using FT–IR studies, we have inferred the existence of H+ outside the channel in oxyhydroxyapatites and provided possible atomic coordinates for a H atom in HAsO42−, leading to a proposed formulation of the compound as Cd5(AsO4)3−x(HAsO4)xCl0.58(OH)0.42−x−(y/2)Ox+(y/2)□y/2.

A grid-like two-dimensional AgIcoordination polymer: poly[[[μ3-N′-(4-cyanobenzylidene)isonicotinohydrazide]silver(I)] perchlorate]

Niu, C.-Y. — 2008-08-09

This study presents new coordinating modes of a Schiff base with three coordinating groups and an interesting two-dimensional framework based on two types of constructing units. In the title compound, {[Ag(C14H10N4O)]ClO4}n, the AgI ion is coordinated by three N atoms and one O atom from three different N′-(4-cyanobenzylidene)isonicotinohydrazide (L) ligands, forming a primary distorted square-planar coordination geometry. Two ligands each bridge two metal centres through one carbonitrile N atom in a monodentate mode and the hydrazide N and O atoms in a bidentate mode to form a small centrosymmetric (2+2)-Ag2L2 ring as a principal constructing unit. The pyridyl N atoms from four ligands in four of these small rings coordinate to Ag atoms in adjacent rings to form a large hexanuclear silver grid. A two-dimensional framework of rectangular grids is constructed from these small rings and large grids. Two perchlorate anions are located in each large grid and are bound to the grid by N—H...O hydrogen bonding. Crosslinking between the layers is achieved through long Ag...O interactions between the perchlorate anions and Ag atoms in adjacent layers.

Bis{μ-3-[3-(2-pyridyl)pyrazol-1-ylmethyl]pyridine}disilver(I) bis(trifluoromethanesulfonate): effect of counter-anions on the self-assembly of coordination complexes

Liu, C.-S. — 2008-08-09

As part of a study on the effect of different counter-anions on the self-assembly of coordination complexes, a new dinuclear AgI complex, [Ag2(C14H12N4)2](CF3SO3)2, with the 3-[3-(2-pyridyl)pyrazol-1-ylmethyl]pyridine (L) ligand was obtained through the reaction of L with AgCF3SO3. In this complex, each AgI center in the centrosymmetric dinuclear complex cation is coordinated by two pyridine and one pyrazole N-atom donor of two inversion-related L ligands in a trigonal planar geometry. This forms a unique box-like cyclic dimer with an intramolecular nonbonding Ag...Ag separation of 6.379 (7) Å. Weak Ag...CF3SO3 and C—H...X (X = O and F) hydrogen-bonding interactions, together with π–π stacking interactions, link the complex cations along the [001] and [1\overline{1}0] directions, respectively, generating two different one-dimensional chains and then an overall two-dimensional network of the complex running parallel to the (110) plane. Comparison of the structural differences with previous findings suggests that the presence of different counter-anions plays an important role in the construction of such supramolecular frameworks.

cis-Dichloridobis(1,10-phenanthroline-5,6-diol-κ2N,N′)manganese(II): a supramolecular chain formed via O—H...Cl bonds and aromatic stacking

Guan, X.-H. — 2008-08-19

The title compound, [MnCl2(C12H8N2O2)2], displays a novel supramolecular chain formed by intermolecular O—H...Cl hydrogen bonds and aromatic stacking. The molecule has crystallographically imposed twofold symmetry with the MnII atom on the twofold axis. In the 1,10-phenanthroline-5,6-diol ligand, each H atom of the two hydroxy groups is oriented towards the other hydroxy O atom. Both hydroxy groups form intermolecular O—H...Cl hydrogen bonds with a single Cl atom of an adjacent molecule. These hydrogen bonds connect the molecules via operation of the molecular twofold axis and the centre of inversion of the crystal lattice, forming a doubly-bridged one-dimensional structure with Mn atoms as the nodes. Strong aromatic π-stacking between two antiparallel neighbouring 1,10-phenanthroline-5,6-diol ligands also helps to stabilize the chain.

A novel three-dimensional coordination polymer constructed from pyrazine and copper(I): poly[[copper(I)-di-μ2-pyrazine-κ4N:N′] 3,5-dicarboxybenzenesulfonate monohydrate]

Guo, H.-X. — 2008-08-19

In the title metal–organic framework complex, {[Cu(C4H4N2)2](C8H5O7S)·H2O}n or {[CuI(pyz)2](H2SIP)·H2O}n (pyz is pyrazine and H3SIP is 5-sulfoisophthalic acid or 3,5-dicarboxybenzenesulfonic acid), the asymmetric unit is composed of one copper(I) center, one whole pyrazine ligand, two half pyrazine ligands lying about inversion centres, one H2SIP− anion and one lattice water molecule, wherein each CuI atom is in a slightly distorted tetrahedral coordination environment completed by four pyrazine N atoms, with the Cu—N bond lengths in the range 2.017 (3)–2.061 (3) Å. The structure features a three-dimensional diamondoid network with one-dimensional channels occupied by H2SIP− anions and lattice water molecules. Interestingly, the guest–water hydrogen-bonded network is also a diamondoid network, which interpenetrates the metal–pyrazine network.

2-tert-Butyl-5-methyl-7,8-dihydro-6H-cyclopenta[e]pyrazolo[1,5-a]pyrimidine: molecular stacks built from C—H...π(pyrazole) hydrogen bonds and π–π stacking interactions

Portilla, J. — 2008-08-09

In the title compound, C14H19N3, the bond distances within the heterocyclic portion of the molecule indicate incomplete π delocalization. The molecules are linked into stacks by a combination of two C—H...π(pyrazole) hydrogen bonds and two independent π–π stacking interactions between inversion-related pyrimidine rings. The significance of this study lies in its observation of significant differences in both molecular conformation and supramolecular aggregation between the title compound, an example of a 2-alkylpyrazolo[1,5-a]pyrimidine, and some analogous 2-arylpyrazolo[1,5-a]pyrimidines.

Two azo pigments based on β-naphthol

Schmidt, M.U. — 2008-08-09

There has been much discussion in the literature of the azo–hydrazone tautomerism of pigments. All commercial azo pigments with β-naphthol as the coupling compound adopt the hydrazone tautomeric form (Ph—NH—N=C) in the solid state. In contrast, the red pigments 1-[4-(dimethylamino)phenyldiazenyl]-2-naphthol, C18H17N3O, (1a), and 1-[4-(diethylamino)phenyldiazenyl]-2-naphthol, C20H21N3O, (1b), have been reported to be azo tautomers or a mixture of azo and hydrazone tautomers in the solid state. To prove these observations, both compounds were synthesized, recrystallized and their crystal structures redetermined by single-crystal structure analysis. Difference electron-density maps show that the H atoms of the hydroxyl groups are indeed bonded to the O atoms. Nevertheless, a small amount of the hydrazone form seems to be present. Hence, the compounds are close to being `real' azo compounds. Compound (1a) crystallizes with a herring-bone structure and compound (1b) forms a rare double herring-bone structure.

Imidazolium-based ionic liquid salts: 3,3′-dimethyl-1,1′-(1,4-phenylenedimethylene)diimidazolium bis(tetrafluoroborate) and 3,3′-di-n-butyl-1,1′-(1,4-phenylenedimethylene)diimidazolium bis(trifluoromethanesulfonate)

Ganesan, K. — 2008-08-09

Crystallization of the ionic liquid 3,3′-dimethyl-1,1′-(1,4-phenylenedimethylene)diimidazolium bis(tetrafluoroborate), C16H20N42+·2BF4−, (I), from its solution in water has permitted the first single-crystal study of an imidazolium-based ionic liquid having a tetrafluoroborate ion as counter-ion. Despite the expectation that the anion would not participate in nonclassical hydrogen bonding, the ionic liquid features C—H...F hydrogen bonds. The dication lies about a center of inversion. The ionic liquid 3,3′-di-n-butyl-1,1′-(1,4-phenylenedimethylene)diimidazolium bis(trifluoromethanesulfonate), C22H32N42+·2CF3SO3−, (II), features both C—H...F and C—H...O hydrogen bonds.

Hydrogen-bonding one-dimensional chains containing the R42(8) motif in the ammonium salts 1-naphthylammonium iodide and naphthalene-1,8-diyldiammonium diiodide

Lemmerer, A. — 2008-08-09

In 1-naphthylammonium iodide, C10H10N+·I−, and naphthalene-1,8-diyldiammonium diiodide, C10H12N22+·2I−, the predominant hydrogen-bonding pattern can be described using the graph-set notation R42(8). This is the first report of a structure of a diprotonated naphthalene-1,8-diyldiammonium salt.

Conformation and hydrogen bonding for the bicyclic compound 3-thiabicyclo[3.2.0]heptane-6,7-dicarboxylic acid 3,3-dioxide

Pett, V.B. — 2008-08-09

The initial goal of this work was to verify the geometry of the product of a photochemical reaction, viz. the title compound, C8H10O6S, (II). Our crystallographic study firmly establishes the cis–anti–cis nature of the substituents on the cyclobutane ring. The geometry is also designated as exo, where exo signifies that the five-membered ring is on the opposite side of the central cyclobutane ring from the carboxylic acid substituents. The structure determination reveals two molecules, A and B, in the asymmetric unit that display substantially different conformations of the bicyclic core: the cyclobutane ring puckering angles are 22 and 3°, and the sulfolane ring conformations are twist (S-exo) and envelope (S-endo). Intrigued by this variation, we then compared the conformations of other molecules in the Cambridge Structural Database that have sulfolane rings fused to cyclobutane rings. In this class of compound, there are five examples of saturated cyclobutane rings, with ring puckering angles ranging from 3 to 35°. The sulfolane rings were more similar: four of the six molecules exhibit envelope conformations with S-endo, as in molecule B of (II). Despite the conformational differences, the hydrogen-bonding scheme for both molecules is similar: carboxyl –OH groups form hydrogen bonds with carboxyl and sulfone O atoms. Alternating A and B molecules joined by hydrogen bonds between sulfone O atoms and carboxyl –OH groups form parallel chains that extend in the ac plane. Other hydrogen bonds between the carboxyl groups link the chains along the b axis.

An unusual two-dimensional hydrogen-bonding network in bis(2,9-dimethyl-1,10-phenanthrolin-1-ium) peroxodisulfate dihydrate

Harvey, M.A. — 2008-08-09

The title compound, 2C14H13N2+·S2O82−·2H2O, is a protonated amine salt which is formed from two rather uncommon ionic species, namely a peroxodisulfate (pds2−) anion, which lies across a crystallographic inversion centre, and a 2,9-dimethyl-1,10-phenanthrolin-1-ium (Hdmph+) cation lying in a general position. Each pds2− anion binds to two water molecules through strong water–peroxo O—H...O interactions, giving rise to an unprecedented planar network of hydrogen-bonded macrocycles which run parallel to (100). The atoms of the large R88(30) rings are provided by four water molecules bridging in fully extended form (...H—O—H...) and four pds2− anions alternately acting as long (...O—S—O—O—S—O...) and short (...O—S—O...) bridges. The Hdmph+ cations, in turn, bind to these units through hydrogen bonds involving their protonated N atoms. In addition, the crystal structure also contains π–π and aromatic–peroxo C—H...O interactions.

A structural systematic study of three isomers of difluoro-N-(4-pyridyl)benzamide

McMahon, J. — 2008-08-09

The isomers 2,3-, (I), 2,4-, (II), and 2,5-difluoro-N-(4-pyridyl)benzamide, (III), all with formula C12H8F2N2O, all exhibit intramolecular C—H...O=C and N—H...F contacts [both with S(6) motifs]. In (I), intermolecular N—H...O=C interactions form one-dimensional chains along [010] [N...O = 3.0181 (16) Å], with weaker C—H...N interactions linking the chains into sheets parallel to the [001] plane, further linked into pairs via C—H...F contacts about inversion centres; a three-dimensional herring-bone network forms via C—H...π(py) (py is pyridyl) interactions. In (II), weak aromatic C—H...N(py) interactions form one-dimensional zigzag chains along [001]; no other interactions with H...N/O/F < 2.50 Å are present, apart from long N/C—H...O=C and C—H...F contacts. In (III), N—H...N(py) interactions form one-dimensional zigzag chains [as C(6) chains] along [010] augmented by a myriad of weak C—H...π(arene) and O=C...O=C interactions and C—H...O/N/F contacts. Compound (III) is isomorphous with the parent N-(4-pyridyl)benzamide [Noveron, Lah, Del Sesto, Arif, Miller & Stang (2002). J. Am. Chem. Soc. 124, 6613–6625] and the three 2/3/4-fluoro-N-(4-pyridyl)benzamides [Donnelly, Gallagher & Lough (2008). Acta Cryst. C64, o335–o340]. The study expands our series of fluoro(pyridyl)benzamides and augments our understanding of the competition between strong hydrogen-bond formation and weaker influences on crystal packing.

Hydrogen-bonding versus π–π stacking interactions in dipyrido[f,h]quinoxaline-6,7-dicarbonitrile and 6,7-dicyanodipyrido[f,h]quinoxalin-1-ium chloride dihydrate

Kozlov, L. — 2008-08-13

The solvent-free title compound, C16H6N6, is an aromatic derivative of phenanthroline with an extended π system. It exhibits a remarkable π–π columnar stacking in the crystal structure, with interplanar distances of 3.229 (3) and 3.380 (3) Å, the shorter spacing being between the two molecules within the asymmetric unit. Adjacent units along the stacked arrays are rotated in-plane with respect to one another by approximately 120°. The hydrochloride derivative, C16H7N6+·Cl−·2H2O, in which one of the phenanthroline N atoms has been protonated, crystallized as a dihydrate. The supramolecular organization in this compound is characterized by continuous hydrogen bonding between the component species, yielding two-dimensional hydrogen-bonded networks. This study demonstrates the high significance of the π–π stacking interactions in the solvent-free aromatic system and how they can be undermined by introducing hydrogen-bonding capacity into the ligand.

Weak intermolecular interactions in 11-chloro-2,3,4,5-tetrahydro-1H-cyclohepta[b]quinoline

Novaković, S.B. — 2008-08-13

The title compound, C14H14ClN, is a chloro analogue of tacrine, an acetylcholinesterase inhibitor. The compound comprises a seven-membered alicyclic ring whose CH donor groups are engaged in extensive intermolecular interactions. The important feature of this crystal structure is that, regardless of the presence of two typical hydrogen-bonding acceptors, viz. chlorine and nitrogen, the corresponding C—H...Cl and C—H...N interactions take no significant role in crystal stabilization. The molecules form dimers through π–π interactions with an interplanar distance between interacting pyridine rings of 3.576 (1) Å. Within the dimers, the molecules are additionally interconnected by four C—H...π interactions. The dimers arrange into regular columns via further intermolecular C—H...π interactions.

Hexamethylenediammonium bis(chloroacetate): a three-dimensional hydrogen-bonded framework structure

Ortíz, A. — 2008-08-13

In the title compound, C6H18N22+·2C2H2ClO2−, the cation lies across an inversion centre in the P\overline{1} space group. The ions are linked by two two-centre N—H...O hydrogen bonds and by one three-centre N—H...(O)2 hydrogen bond to form a three-dimensional framework structure. The significance of this study lies in the analysis of the complex hydrogen-bonded structure and in the comparison of this structure with those of other simple hexamethylenediammonium salts.

5α-Androst-3-en-17-one oxime

Andrade, L.C.R. — 2008-08-13

The title compound, C19H29NO, is a C17-oxime derivative of a potent aromatase inhibitor, which surprisingly has been found to have no inhibitory power. It crystallizes with two independent molecules in the asymmetric unit. C=N—O—H...N hydrogen bonds link pairs of molecules to form dimers almost parallel to the bc plane. Cohesion of the structure is also due to another three C—H...O hydrogen bonds directed along the a axis. This hydrogen-bonding scheme can be correlated to the almost complete loss of inhibitory power of the title compound.

N-{3-[(2-Ammonioethyl)amino]propyl}ethane-1,2-diaminium tris(trifluoromethanesulfonate): a salt of a folded triply protonated tetramine

Patroniak, V. — 2008-08-19

The structure of a trifluoromethanesulfonate salt of a nontypical triply protonated linear tetramine, C7H23N43+·3CF3SO3−, with a layered crystal structure is presented. One N atom remains unprotonated. The conformation of the cation is enforced by intra- and intermolecular hydrogen bonds. The crystal structure is built of ca 10 Å deep layers, within which cations and anions are hydrogen bonded. Each layer is only weakly bound to its neighbours. This study shows a rare example of an unsymmetrically protonated polyamine and the relation between the lack of protonation, intramolecular hydrogen bonding and the conformation of the cation.

Three styryl-substituted tetrahydro-1,4-epoxy-1-benzazepines: configurations, conformations and hydrogen-bonded chains

Acosta, L.M. — 2008-08-19

(2SR,4RS)-7-Chloro-2-exo-[(E)-styryl]-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine, C18H16ClNO, (I), crystallizes as a racemic twin in the space group P21 and the molecules are linked into a chain of edge-fused R33(9) rings by a combination of C—H...O and C—H...N hydrogen bonds. The diastereoisomer (2RS,4RS)-7-chloro-2-endo-[(E)-styryl]-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine, (II), also crystallizes as a racemic twin, but in the space group P212121, and a two-centre C—H...N hydrogen bond and a three-centre C—H...(O,N) hydrogen bond combine to link the molecules into a complex chain of rings. In (2R,4R)-7-fluoro-2-endo-[(E)-styryl]-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine, C18H16FNO, (III), which is not isomorphous with (II), the molecules are linked by a single C—H...O hydrogen bond into simple chains, but the molecular arrangements in (II) and (III) are nonetheless very similar. The significance of this study lies in its observation of the variations in molecular configuration and conformation, and in the variation in the supramolecular aggregation, consequent upon modest changes in the peripheral substituents.

Three aryl-substituted tetrahydro-1,4-epoxy-1-benzazepines: hydrogen-bonded structures in two or three dimensions

Gómez, S.L. — 2008-08-19

In (2SR,4RS)-7-chloro-2-exo-(4-chlorophenyl)-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine, C16H13Cl2NO, (I), the molecules are linked by a combination of C—H...O and C—H...N hydrogen bonds into a chain of edge-fused R33(12) rings. The isomeric compound (2S,4R)-7-chloro-2-exo-(2-chlorophenyl)-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine, (II), crystallizes as a single 2S,4R enantiomer and the molecules are linked into a three-dimensional framework structure by two C—H...O hydrogen bonds and one C—H...π(arene) hydrogen bond. The molecules of (2S,4R)-7-chloro-2-exo-(1-naphthyl)-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine, C20H16ClNO, (III), are also linked into a three-dimensional framework structure, here by one C—H...O hydrogen bond and two C—H...π(arene) hydrogen bonds. The significance of this study lies in its observation of the variations in molecular configuration and conformation, and in the variation in the patterns of supramolecular aggregation, consequent upon modest changes in the peripheral substituents.

Three tetrahydro-1,4-epoxy-1-benzazepines carrying pendent heterocyclic substituents: supramolecular structures in zero, one or two dimensions

Blanco, M.C. — 2008-08-19

(2SR,4RS)-7-Fluoro-2-exo-(2-furyl)-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine, C14H12FNO2, (I), crystallizes with Z′ = 2 in the space group P21/c. A combination of three C—H...O hydrogen bonds and one C—H...N hydrogen bond links the molecules into a complex chain of rings, and pairs of such chains are linked into a tube-like structure by two C—H...π(arene) hydrogen bonds. There are no hydrogen bonds in the structure of racemic (2SR,4RS)-2-exo-(5-bromo-2-thienyl)-7-fluoro-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine, C14H11BrFNOS, (II), while the molecules of (2S,4R)-2-exo-(5-bromo-2-thienyl)-7-trifluoromethoxy-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine, C15H14BrF3NO2S, (III), are linked into sheets by a combination of two C—H...O hydrogen bonds and one C—H...π(arene) hydrogen bond. The significance of this study lies in its observation of the wide variation in the patterns of supramolecular aggregation, consequent upon modest changes in the peripheral substituents.