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Acta Crystallographica Section C: Crystal Structure Communications
The crystal structure of thallium carbonate, Tl2CO3 (C2/m, Z = 4), is stable at least up to 3.56 GPa, as demonstrated by hydrostatic single-crystal X-ray diffraction measurements in a diamond anvil cell at room temperature. Our results contradict earlier observations from the literature, which found a structural phase transition for this compound at about 2 GPa. Under atmospheric conditions, all atoms except for one O atom reside on the mirror plane in the high-pressure structure. The compression mainly affects the part of the structure where the nonbonded electron lone pairs on the Tl+ cations are located.
Iron was inserted into the known crystal structure of the bismuth phosphate oxide Bi6.67(PO4)4O4 to ascertain its location in the vacancies associated with the bismuth ion located at the origin of the unit cell. Single-crystal X-ray diffraction refinements converged to a model of composition Bi6(Bi0.32Fe0.68)(PO4)4O4 (hexabismuth iron tetraphosphate tetraoxide), in which Bi and Fe are displaced from the origin giving rise to a random distribution over the 2i sites instead of 1a, the origin of space group P\overline{1}. The isotropic displacement parameter for Bi/Fe has a reasonable value in this model. This structure establishes for the first time that Fe substitutes in the Bi-deficient site in this series of materials and that Fe and Bi are disordered around the center of symmetry. These results enhance understanding of the crystal chemistry of these main group phosphates that are of interest in ion transport.
The title compound, catena-poly[[tris(μ-4-methylbenzoato)-κ2O:O;κ4O:O′-(4-methylbenzoato-κ2O,O′)dizinc(II)]-μ-4,4′-bipyridine-κ2N:N′], [Zn2(C8H7O2)4(C10H8N2)]n, is a novel coordination polymer. The asymmetric unit contains two unique ZnII ions, four 4-methylbenzoate ligands and one 4,4′-bipyridine (4,4′-bpy) ligand, all in general positions. The four 4-methylbenzoate ligands link the two ZnII centres to form a dinuclear unit, with a Zn...Zn separation of 3.188 (2) Å, which can be regarded as a supramolecular secondary building unit (SBU). These SBUs are further bridged by 4,4′-bpy ligands, forming a novel one-dimensional infinite chain. There are π–π stacking interactions between the benzene rings of the 4-methylbenzoate ligands and the pyridyl rings of the 4,4′-bpy ligands, leading to the formation of a corrugated layer. These layers are further assembled via C—H...O hydrogen bonds into a three-dimensional supramolecular network structure. Coordination polymers such as the title compound are of interest for their potential applications as functional materials.
The title compound, [Ni2(C5H5)(C10H15)(C12H8)] or [Ni(C10H15){Ni(C5H5)(C12H8)}], is a rare example (and the first obtained from nickelafluorenyllithium) of an analogue of nickelocene in which the central Ni atom is coordinated to one pentamethylcyclopentadienyl ring and one nickelafluorenyl ring. Both rings lie almost parallel to one another: the dihedral angle between the planes which include these rings is 4.4 (1)°. Slip parameter analysis indicates that the bonding mode of the central Ni atom to the nickelacyclic ring is between η3 and η5. Two-dimensional layers of molecules are formed by C—H...π interactions.
In the title compound, [Fe(NCS)2(C12H10N4)(CH4O)2]n, at 153 (2) K, the Fe atom is located on an inversion centre, as is the centre of the N—N bond in the ligand molecule. The structure contains a one-dimensional coordination polymer with an Fe...Fe distance of 15.866 (7) Å and can be described as two interpenetrating six-connected primitive cubic (pcu) three-dimensional networks when additional intermolecular O—H...S hydrogen bonds are taken into account. The compound is not isostructural with the corresponding MnII compound as they differ in the rotation around the M—O bond by 90°, giving rise to completely different hydrogen-bond patterns. This study demonstrates the impact of conformational differences on the final supramolecular arrangement.
The title novel mixed μ2-SH- and μ3-SH-bridged tetranuclear copper(I) complex, cyclo-bis[μ2-bis(diphenylphosphino)amine]di-μ3-sulfanido-di-μ2-sulfanido-tetracopper(I) methanol disolvate, [Cu4(SH)4(C24H21NP2)2]·2CH3OH, has crystallographically imposed centrosymmetry and affords a neutral Cu4S4 core with a distorted step-like structure. The distances of 2.8458 (16) and 2.8179 (16) Å between copper(I) centres indicate the presence of ligand-supported Cu...Cu interactions. Strong N—H...O and O—H...S hydrogen bonds between the tetranuclear cluster and methanol solvent molecules result in a two-dimensional hydrogen-bonded supramolecular network. This complex is the first example of a coinage tetranuclear metal complex with mixed μ2-SH- and μ3-SH-bridged chromophores.
The title novel heterometallic 3d–4f coordination polymer, {[CuEr2(C5HN2O4)2(C2O4)(H2O)6]·3H2O}n, has a three-dimensional metal–organic framework composed of two types of metal atoms (one CuII and two ErIII) and two types of bridging anionic ligands [3,5-dicarboxylatopyrazolate(3−) (ptc3−) and oxalate]. The CuII atom is four-coordinated in a square geometry. The ErIII atoms are both eight-coordinated, but the geometries at the two atoms appear different, viz. triangular dodecahedral and bicapped trigonal prismatic. One of the oxalate anions is located on a twofold axis and the other lies about an inversion centre. Both oxalate anions act as bis-bidentate ligands bridging the latter type of Er atoms in parallel zigzag chains. The pdc3− anions act as quinquedentate ligands not only chelating the CuII and the triangular dodecahedral ErIII centres in a bis-bidentate bridging mode, but also connecting to ErIII centres of both types in a monodentate bridging mode. Thus, a three-dimensional metal–organic framework is generated, and hydrogen bonds link the metal–organic framework with the uncoordinated water molecules. This study describes the first example of a three-dimensional 3d–4f coordination polymer based on pyrazole-3,5-dicarboxylate and oxalate, and therefore demonstrates further the usefulness of pyrazoledicarboxylate as a versatile multidentate ligand for constructing heterometallic 3d–4f coordination polymers with interesting architectures.
Compounds trans-tetraaquadichloridocobalt(II)–piperazine-2,5-dione (1/1), [CoCl2(H2O)4]·C4H6N2O2, (I), and trans-tetraaquadichloridonickel(II)–piperazine-2,5-dione (1/1), [NiCl2(H2O)4]·C4H6N2O2, (II), are isomorphous. In each structure, the metal complex and the piperazinedione unit both lie across centres of inversion in the space group P21/n. The [MCl2(H2O)4] units (M = Co or Ni) are linked by O—H...Cl hydrogen bonds into sheets of R22(8) and R42(12) rings, and these sheets are linked by the piperazinedione components via a combination of O—H...O and N—H...Cl hydrogen bonds into a three-dimensional framework. In catena-poly[[[trans-diaquacopper(II)]-di-μ-chlorido] piperazine-2,5-dione solvate], {[CuCl2(H2O)2]·C4H6N2O2}n, (III), the metal ion and the piperazine unit both lie across centres of inversion in the space group I2/a. The coordination polymer forms chains of centrosymmetric [CuCl2(H2O)2] units running parallel to [010] and these are linked by the piperazinedione units into a three-dimensional framework structure. In poly[μ3-nitrato-μ2-piperazine-2,5-dione-silver(I)], [Ag(NO3)(C4H6N2O2)]n, (IV), the silver and nitrate ions lie on mirror planes in the space group Pnma, while the piperazinedione unit lies across a centre of inversion. The compound is a coordination polymer containing five-coordinate approximately square-pyramidal Ag, in which the ligating O atoms are derived from three different nitrate ligands and two different piperazinedione ligands. The ionic components form sheets in which each anion is coordinated to three different cations, and these sheets are linked into a three-dimensional framework by the organic ligands, each of which coordinates to two different Ag centres. The significance of this study lies in its demonstration of a wide variety of framework types built from a common and very simple organic component with simple metal salts.
The title complex, [Er2(C15H9O2)6(C12H8N2)2], has a centrosymmetric binuclear cage structure in which the two ErIII atoms are both nine-coordinated and are bridged by four bulky anthracene-9-carboxylate (L) ligands, with a nonbonding Er...Er separation of 3.9041 (2) Å. The L groups coordinate each ErIII atom in three different ways. The results reported here reveal that the bulky anthracene skeleton of the L ligand plays an important role in the formation of the complex by virtue of intra- and intermolecular π–π stacking and C—H...π interactions.
The title compound, C8H9NS, has four symmetry-independent molecules in the asymmetric unit. These molecules link into two independent infinite N—H...S hydrogen-bonded chains in the a-axis direction with graph-set notation C22(8). The NH—CS group adopts a trans conformation and forms a dihedral angle of about 50° with the phenyl ring. The intermolecular hydrogen-bond energy calculated by the density functional theory (DFT) method is −14.95 kJ mol−1. The correlation between the IR spectrum of this compound and the hydrogen-bond energy is also discussed. This molecular system is of interest because of its biological function.
The geometric features of 1-(4-nitrophenyl)-1H-tetrazol-5-amine, C7H6N6O2, correspond to the presence of the essential interaction of the 5-amino group lone pair with the π system of the tetrazole ring. Intermolecular N—H...N and N—H...O hydrogen bonds result in the formation of infinite chains running along the [110] direction and involve centrosymmetric ring structures with motifs R22(8) and R22(20). Molecules of {(E)-[1-(4-ethoxyphenyl)-1H-tetrazol-5-yl]iminomethyl}dimethylamine, C12H16N6O, are essentially flattened, which facilitates the formation of a conjugated system spanning the whole molecule. Conjugation in the azomethine N=C—N fragment results in practically the same length for the formal double and single bonds.
The title compound [systematic name: 7-(2-deoxy-β-d-erythro-pentofuranosyl)-3,7-dihydro-4H-pyrrolo[2,3-d]pyrimidin-4-one], C11H13N3O4, represents an acid-stable derivative of 2′-deoxyinosine. It exhibits an anti glycosylic bond conformation, with a χ torsion angle of 113.30 (15)°. The furanose moiety adopts an S-type sugar pucker 4T3, with P = 221.8 (1)° and τm = 40.4 (1)°. The conformation at the exocyclic C4′—C5′ bond of the furanose ring is ap (trans), with γ = 167.14 (10)°. The extended structure forms a three-dimensional hydrogen-bond network involving O—H...O, N—H...O and C—H...O hydrogen bonds. The title compound forms an uncommon hydrogen bond between a CH group of the pyrrole system and the ring O atom of the sugar moiety of a neighbouring molecule.
The molecular structure of the title compound, C12H15NO4, has several features related to steric hindrance due to the ester and dimethylamine groups being located ortho with respect to one another. In particular, the carbonyl group of the ester is not coplanar with the ring, the amine N atom is in a pyramidal arrangement [the N atom is 0.2161 (12) Å from the three C atoms to which it is bonded] and the C atom of the adjacent ester group lies 0.3784 (14) Å out of the plane of the aromatic ring. The deformations found in the X-ray structure have been confirmed by ab initio quantum mechanical calculations.
The crystal and molecular structure of the title compound, C15H26O4Si2, reveals a self-assembly facilitated via the rare co-existence of dimeric and catemeric patterns, which is attributed to the influence of the trimethylsilyl groups. The structure is dicussed in the context of a database search and subsequent analysis of structures of cis-1,2-dicarboxylic acids.
The reaction of 2-phenyl-2H-1,2,3-triazole-4-carbaldehyde with triethylenetetramine leads to the formation of a new binucleating ligand, viz. the title compound, C33H33N13, demonstrating that this structure has the potential for more flexible rational design and tailoring. The title molecule is rendered quite rigid by the formation of a five-membered imidazolidine ring and there are four independent instances of π–π interactions. Both sides of each of the three aromatic arms take part in these interactions, forming a neat three-dimensional array structure.
For the hydrated proton-transfer compound 6-chloro-9-[(4-diethylammonio-2-methylbutyl)amino]-2-methoxyacridinium 3-carboxylato-4-hydroxybenzenesulfonate dihydrate, C23H32ClN3O2+·C7H4O6S2−·2H2O, (I), the conformational features, specifically those of the extended side chain at the 9-position of the acridine parent, have been compared with those of quinacrinium dichloride dihydrate (the drug atabrine or mepacrine). Racemic compound (I) has a three-dimensional hydrogen-bonded framework structure similar to atabrine but also involves the water molecules and both the carboxylate and sulfonate groups of the anion in structure extension. The comparable conformational features found in this uncommon derivative of quinacrine indicate that (I) has potential as a possible pharmaceutical substitute for atabrine.
The title methanol solvate, C24H22N4O5·CH3OH, forms an extended three-dimensional hydrogen-bonded structure, assisted by the presence of several good donor and acceptor sites. It shows none of the crystal packing features typically expected of piperazinediones, such as amide-to-amide R22(8) hydrogen bonding. In this structure the methanol solvent appears to play only a space-filling role; it is not involved in any hydrogen bonding and instead is disordered over several sites. This study reports, to the best of our knowledge, the first crystal structure of an indane-containing piperazinedione compound which exhibits a three-dimensional hydrogen-bonded structure formed by classical (N—H...O and N—H...N) hydrogen-bonding interactions.
The title compound, C14H12N4O2, is the first example of a heterocyclic substituted hydroxamic derivative. The asymmetric unit consists of two molecules. The molecules are linked into centrosymmetric R44(20) tetramers by four strong hydrogen bonds of the N—H...O and N—H...N types. These tetramers are connected through C—H...O interactions into a three-dimensional network.
The analysis of the crystal structures of rac-3-benzoyl-2-methylpropionic acid, C11H12O3, (I), morpholinium rac-3-benzoyl-2-methylpropionate monohydrate, C4H10NO+·C11H11O3−·H2O, (II), pyridinium [hydrogen bis(rac-3-benzoyl-2-methylpropionate)], C5H6N+·(H+·2C11H11O3−), (III), and pyrrolidinium rac-3-benzoyl-2-methylpropionate rac-3-benzoyl-2-methylpropionic acid, C4H10N+·C11H11O3−·C11H12O3, (IV), has enabled us to predict and understand the behaviour of these compounds in Yang photocyclization. Molecules containing the Ar—CO—C—C—CH fragment can undergo Yang photocyclization in solvents but they can be photoinert in the crystalline state. In the case of the compounds studied here, the long distances between the O atom of the carbonyl group and the γ-H atom, and between the C atom of the carbonyl group and the γ-C atom preclude Yang photocyclization in the crystals. Molecules of (I) are deprotonated in a different manner depending on the kind of organic base used. In the crystal structure of (III), strong centrosymmetric O...H...O hydrogen bonds are observed.
In the closely related quinoline compounds 8-nitro-2-(trichloromethyl)quinoline, (I), 6-nitro-2-(trichloromethyl)quinoline, (II), and 5-nitro-2-(trichloromethyl)quinoline, (III), all C10H5Cl3N2O2, which are of both reactivity and pharmacological interest, and for which the biological activity and cytotoxicity appear to be based on the positions of the CCl3 and nitro substituents, the nitro group is only coplanar with its aromatic substrate in (II). The deviation of the nitro group from coplanarity is concluded to be a function of both its position with respect to the trichloromethyl group and the intermolecular contacts in which it participates. The discrepancies between the crystal structures and the molecular shapes predicted by ab initio calculations are also explained in these terms. The quinoline ring is not rigorously planar in any of the structures, which may be explained by stress produced by the CCl3 substituent.
The CuI-catalysed 1,3-dipolar cycloaddition of an azide and a terminal alkyne is becoming an increasingly popular tool for synthetic chemists. This is the most representative of the so-called `click reactions' and it is used to generate 1,4-disubstituted triazoles in high yield. During studies on such cycloaddition reactions, a reduced reactivity of an α-glucosyl azide with respect to the corresponding β-anomer was observed. With the aim of understanding this phenomenon, the structure of the title compound, C14H19N3O9, has been determined at 140 K. The glucopyranosyl ring appears in a regular 4C1 chair conformation with all the substituents in equatorial positions, except for the anomeric azide group, which adopts an axial orientation. The observed bond lengths are consistent with a strong anomeric effect, which is reflected in a change in dipolar character and hence reduced reactivity of the α-glucosyl azide.
In cyclotridecanone 2,4-dinitrophenylhydrazone, C19H28N4O4, the 13-membered carbocycle exists in the triangular [337] conformation. The 2,4-dinitrophenylhydrazone group is almost perpendicular to the 13-membered ring, with a dihedral angle of 82.66 (2)° between the mean planes. The dinitrophenylhydrazone rings are packed parallel to each other and separated by 3.28 (1) Å. The NH group forms an intramolecular hydrogen bond to a nitro O atom, and there is a weaker C—H...O interaction between a cyclotridecane CH group and a symmetry-related 4-nitro O atom, with a C...O distance of 3.436 (2) Å and a 150° angle about the H atom. The structure, in combination with additional evidence, indicates that [337] is the preferred conformation of cyclotridecane and other simple 13-membered rings.
Tripivaloylmethane [systematic name: 4-(2,2-dimethylpropanoyl)-2,2,6,6-tetramethylheptane-3,5-dione], C16H28O3, is known to crystallize at room temperature in the space group R3m with three molecules in the unit cell. The molecules are conformationally chiral and pack so that each molecular site is occupied with equal probability by the two enantiomers. Upon cooling to 110 K, the structure partially orders; two molecules in the unit cell order into two different conformations of opposite chirality, while the third remains disordered. The symmetry of the resulting crystal is P3, with each of the molecules lying about a different threefold rotation axis. This paper describes an unusual case of order–disorder phase transition in which the structure partially orders by changes of molecular conformation in the single crystals. Such behaviour is of interest in the study of phase transitions and molecular motion in the solid state.
The title carbazolyl boronic ester, C22H28BNO2, (I), is a building block for the synthesis of new carbazole derivatives of potential utility as pharmaceutically active compounds. The crystal structure of (I) and of the title bromocarbazole compound, C16H16BrN, (II), the synthetic precursor of (I), were solved and analysed with the aim of understanding the lack of reactivity of (I) under Suzuki cross-coupling reaction conditions. In both structures, the methyl groups are coplanar with the carbazole ring system, and the ethyl group lies out of the carbazole plane. The dioxaborolane ring of boronic ester (I) adopts a half-chair conformation but lies approximately in a planar orientation with respect of the carbazole ring system, whereas the Br atom of (II) is coplanar with the carbazole plane. In (I), the carbazole–boronic ester C—B bond length is 1.5435 (14) Å, which is somewhat shorter than the usual value of 1.57 Å.
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