Acta Crystallographica Section C

Dipotassium trimanganese(II) tetrakis(hydrogenphosphite), K2[Mn3(HPO3)4]

Hamchaoui, F. — 2009-06-13

The title compound is a new mixed alkali/3d metal phosphite. It exhibits a layered structure formed by linear Mn3O12 trimer units which contain face-sharing MnO6 octahedra interconnected by (HPO3)2− phosphite oxoanions. The K+ cations located between the anionic [Mn3(HPO3)4]2− sheets are ninefold coordinated. The presence of the alkaline ion leads to the highest symmetry and shortest interlayer distance compared with two previous compounds showing the same anionic framework and having ammonium salts as cations. The compound crystallizes in the space group R\overline{3}m, with two crystallographically independent Mn atoms occupying sites of \overline{3}m and 3m symmetry. All the other atoms, except for the phosphite O atoms, are located on special positions with 3m symmetry.

The first three-dimensional vanadium hypophosphite

Maouel, H.A. — 2009-06-13

The title synthesized hypophosphite has the formula V(H2PO2)3. Its structure is based on VO6 octahedra and (H2PO2)− pseudo-tetrahedra. The asymmetric unit contains two crystallographically distinct V atoms and six independent (H2PO2)− groups. The connection of the polyhedra generates [VPO6H2]6− chains extended along a, b and c, leading to the first three-dimensional network of an anhydrous transition metal hypophosphite.

Dicopper(II) trihydroxide cyanoureate dihydrate

Chippindale, A.M. — 2009-06-20

The title compound, poly[[μ-cyanoureato-tri-μ-hydroxido-dicopper(II)] dihydrate], {[Cu2(C2H2N3O)(OH)3]·2H2O}n, is a new layered copper(II) hydroxide salt (LHS) with cyanoureate ions and water molecules in the interlayer space. The three distinct copper(II) ions have distorted octahedral geometry: one Cu (symmetry \overline{1}) is coordinated to six hydroxide groups (4OH + 2OH), whilst the other two Cu atoms (symmetries \overline{1} and 1) are coordinated to four hydroxides and two N atoms from nitrile groups of the cyanoureate ions (4OH + 2N). The structure is held together by hydrogen-bonding interactions between the terminal –NH2 groups and the central cyanamide N atoms of organic anions associated with neighbouring layers.

The centrosymmetric metal metaborate KCdB3O6

Jin, S. — 2009-06-20

The title compound, potassium cadmium metaborate, crystallizes in a monoclinic cell, featuring infinite one-dimensional CdO5 chains and trigonal planar B atoms in hexagonal B3O6 metaborate ions. The trigonal bipyramidal CdO5 chains and metaborate ions are interlinked to form a three-dimensional framework, creating channels running parallel to the [10\overline{1}] direction in which the potassium ions reside.

catena-Poly[[[aqua(ethylenediamine-κ2N,N′)(nitrato-κO)copper(II)]-μ-4,4′-dithiodipyridine-κ2N:N′] nitrate monohydrate]

Seidel, R.W. — 2009-06-06

The title compound, {[Cu(NO3)(C2H4N2)(C10H8N2S2)(H2O)]NO3·H2O}n, is composed of a one-dimensional linear coordination polymer involving cis-protected copper(II) ions and a 4,4′-dithiodipyridine bridging ligand. The polymeric chains run along the c-axis direction. N—H...O and O—H...O hydrogen bonds involving the coordinating amine groups, nitrate ions and water molecules, as well as cocrystallized noncoordinating nitrate ions and water molecules, generate a three-dimensional structure.

Di-μ-chlorido-bis[chlorido(4′-p-tolyl-2,2′:6′,2′′-terpyridine-κ3N,N′,N′′)nickel(II)]: a supramolecular system constructed by C—H...Cl interactions

Chen, Y.-L. — 2009-06-06

The title complex, [Ni2Cl4(C22H17N3)2], was synthesized solvothermally. The molecule is a centrosymmetric dimer with the unique NiII centre in a distorted octahedral N3Cl3 coordination environment. The chloride bridges are highly asymmetric. In the 4′-p-tolyl-2,2′:6′,2′′-terpyridine ligand, the p-tolyl group is perfectly coplanar with the attached pyridine ring, and this differs from the situation found in previously reported compounds; however, there are no π–π interactions between the ligands. The terminal Cl atom forms four intermolecular C—H...Cl hydrogen bonds with one methyl and three methine groups. The methyl group also forms intermolecular C—H...π interactions with a pyridine ring. These nonclassical hydrogen bonds extend the molecule into a three-dimensional network.

Two polymeric structures with a benzene-1,2,4,5-tetracarboxylate ligand acting in μ2- and μ4-bridging modes

Atria, A.M. — 2009-06-06

catena-Poly[[tetraaquabis(1H-pyrazole-κN2)nickel(II)] [[diaquabis(1H-pyrazole-κN2)nickel(II)]-μ-benzene-1,2,4,5-tetracarboxylato-κ2O1:O4] tetrahydrate], {[Ni(C3H4N2)2(H2O)4][Ni(C10H2O8)(C3H4N2)2(H2O)2]·4H2O}n, (I), and poly[[(μ4-benzene-1,2,4,5-tetracarboxylato-κ4O1:O2:O4:O5)octakis(1H-pyrazole-κN2)dicobalt(II)] tetrahydrate], {[Co2(C10H2O8)(C3H4N2)8]·4H2O}n, (II), are polymeric compounds crystallizing in the space group P\overline{1}, with two independent metallic cations and one benzene-1,2,4,5-tetracarboxylate (btc) anion, each lying on symmetry centres. Individual coordination polyhedra are regular and the main differences are in the way the btc anion binds [μ2 in (I) and μ4 in (II)], promoting a `chain-like' one-dimensional structure in (I) and a `sieve-like' two-dimensional motif in (II).

Two different one-dimensional structural motifs in [catena-{Cu(tacn)}2Pd(CN)4]Br2·[catena-Cu(tacn)Pd(CN)4]2·H2O (tacn is 1,4,7-triazacyclononane)

Kuchár, J. — 2009-06-13

The title compound, catena-poly[[bis[(triazacyclononane-κ3N,N′,N′′)copper(II)]-di-μ-cyanido-κ4N:C-palladate(II)-di-μ-cyanido-κ4C:N] dibromide bis[[(triazacyclononane-κ3N,N′,N′′)copper(II)]-μ-cyanido-κ2N:C-[dicyanidopalladate(II)]-μ-cyanido-κ2C:N] monohydrate], {[Cu2Pd(CN)4(C6H15N3)2]Br2·[Cu2Pd2(CN)8(C6H15N3)2]·H2O}n, (I), was isolated from an aqueous solution containing tacn·3HBr (tacn is 1,4,7-triazacyclononane), Cu2+ and tetracyanidopalladate(2−) anions. The crystal structure of (I) is essentially ionic and built up of 2,2-electroneutral chains, viz. [Cu(tacn)(NC)–Pd(CN)2–(CN)–], positively charged 2,4-ribbons exhibiting the composition {[Cu(tacn)(NC)2–Pd(CN)2–Cu(tacn)]2n+}n, bromide anions and one disordered water molecule of crystallization. The O atom of the water molecule occupies two unique crystallographic positions, one on a centre of symmetry, which is half occupied, and the other in a general position with one-quarter occupancy. One of the tacn ligands also exhibits disorder. The formation of two different types of one-dimensional structural motif within the same structure is a unique feature of this compound.

Two polymeric nickel(II) complexes with aromatic benzene-1,2,4,5-tetracarboxylate and pyridine-2,5-dicarboxylate linkers

Atria, A.M. — 2009-06-13

(μ-Benzene-1,2,4,5-tetracarboxylato-κ2O1:O4)bis[aquabis(2,2-methylpropane-1,3-diamine-κ2N,N′)nickel(II)] methanol disolvate tetrahydrate, [Ni2(C10H2O8)(C5H14N2)4(H2O)2]·2CH4O·4H2O, (I), is dinuclear, with elemental units built up around an inversion centre halving the benzene-1,2,4,5-tetracarboxylate (btc) anion, which bridges two symmetry-related NiII cations. The octahedral Ni polyhedron is completed by two chelating 2,2-methylpropane-1,3-diamine (dmpda) groups and a terminal aqua ligand. Two methanol and four water solvent molecules are involved in a number of N—H...O and O—H...O hydrogen bonds which define a strongly bound two-dimensional supramolecular structure. The structure of catena-poly[[[bis(2,2-methylpropane-1,3-diamine-κ2N,N′)nickel(II)]-μ-pyridine-2,5-dicarboxylato-κ3O5:N,O2-[(2,2-methylpropane-1,3-diamine-κ2N,N′)nickel(II)]-μ-pyridine-2,5-dicarboxylato-κ3N,O2:O5] octahydrate], {[Ni2(C7H3NO4)2(C5H14N2)3]·8H2O}n, (II), is polymeric, forming twisted chains around three independent Ni centres, two of which lie on inversion centres and the third in a general position. There are three chelating dmpda ligands (one disordered over two equally populated positions), which are each attached to a different cation, and two pyridine-2,5-dicarboxylate (pdc) anions, both chelating the Ni centre in general positions through an –O—C—C—N– loop, while acting as bridges to the remaining two centrosymmetric Ni atoms. There are, in addition, eight noncoordinated water molecules in the structure, some of which are disordered.

Two 18ē TiIV η5-Cp-tris(sec-amido)-type complexes derived from 1H-imidazol-2-yl side-chain functionalized cyclopentadienes

Wang, X. — 2009-06-20

Achiral {2-[2-(η5-cyclopentadienyl)-2-methylpropyl]-1H-imidazolyl-κN1}bis(N,N-diethylamido-κN)titanium(IV), [Ti(C4H10N)2(C12H14N2)], (I), and closely related racemic (SR)-{2-[(η5-cyclopentadienyl)(phenyl)methyl]-1H-imidazolyl-κN1}bis(N,N-diethylamido-κN)titanium(IV), [Ti(C4H10N)2(C15H12N2)], (II), have been prepared by direct reactions of Ti(NEt2)4 and the corresponding 1H-imidazol-2-yl side-chain functionalized cyclopentadienes. In compound (II), there are two crystallographically independent molecules of very similar geometries connected by a noncrystallographic pseudosymmetry operation akin to a 21 screw axis. All Ti-ligating N atoms in both (I) and (II) are in planar environments, which is indicative of an additional N→Ti pπ–dπ donation. This fact and the 18ē nature of both (I) and (II) are additionally supported by quantum chemical single-point density functional theory (DFT) computations.

Bis(di-2-pyridylamine-κ2N2,N2′)(nitrato-κ2O,O′)nickel(II) nitrate

Černák, J. — 2009-06-20

In the ionic title compound, [Ni(NO3)(C10H9N3)2]NO3, the central NiII atom exhibits cis-NiN4O2 octahedral coordination with three chelating ligands, viz. one nitrate anion and two di-2-pyridylamine (dpya) molecules. A second nitrate group acts as a counter-ion. The complex cations and the nitrate anions are also linked by N—H...O hydrogen bonds. The compound was prepared in two different reproducible ways: direct synthesis from Ni(NO3)2 and dpya yielded systematically twinned crystals (the twinning law is discussed), while single crystals were obtained unexpectedly from the Ni(NO3)2/dpya/maleic acid/NaOH system.

Different intermolecular interactions in azido[2-(diphenylphosphino)benzaldehyde semicarbazonato-κ2P,N1,O]nickel(II)

Novaković, S.B. — 2009-06-24

The title compound, [Ni(C20H17N3OP)(N3)], is the first complex with a semicarbazide-based ligand having a P atom as one of the donors. The influence of the P atom on the deformation of the coordination geometry of the NiII ion is evident but less expressed than in the cases of complexes with analogous seleno- and thiosemicarbazide ligands. The torsion angles involving the two bonds formed by the P atom within the six-membered chelate ring have the largest values [C—P—Ni—N = 24.3 (2)° and C—C—P—Ni = −24.2 (4)°], suggesting that the P atom considerably influences the conformation of the ring. Two types of N—H...N hydrogen bond connect the complex units into chains.

Poly[[diaqua(μ3-2,2-dimethylmalonato)cadmium(II)] tetrahydrate]

Guo, M.-L. — 2009-06-24

In the title complex, {[Cd(C5H6O4)(H2O)2]·4H2O}n, the dimethylmalonate–cadmium metal–organic framework co-exists with an extended structure of water molecules, which resembles a sodalite-type framework. In the asymmetric unit, there are five independent solvent water molecules, two of which are in special positions. The Cd atoms are eight-coordinated in a distorted square-antiprismatic geometry by six O atoms of three different dimethylmalonate groups and by two water molecules, and form a two-dimensional honeycomb layer parallel to the bc plane. Two such layers sandwich the hydrogen-bonded water layer, which has a sodalite-type structure with truncated sodalite units composed of coordinated and solvent water molecules. This work is the first example of a dimethylmalonate cadmium complex containing truncated sodalite-type water clusters.

Trinitratobis{N′-[1-(2-pyridyl)ethylidene]isonicotinohydrazide}cerium(III): a three-dimensional cerium–organic supramolecular structure

Zhang, Y.-Y. — 2009-06-24

The CeIII ion in the title complex, [Ce(NO3)3(C13H12N4O)2], is 12-coordinated by six chelating nitrate O atoms and six donors (2 O and 4 N atoms) of two N′-[1-(2-pyridyl)ethylidene]isonicotinohydrazide ligands, exhibiting a bicapped pentagonal-antiprism-type coordination geometry. The title complex possesses C2 point symmetry and is located on a twofold crystallographic axis. Each molecule is linked with four surrounding molecules by four N—H...N hydrogen bonds, resulting in an extended two-dimensional layer parallel to the ab plane, while π–π interactions between pyridine rings from neighboring complex molecules connect the two-dimensional layers into a three-dimensional cerium–organic supramolecular structure.

1,2,3-Trimethoxy-4-[(E)-2-phenylvinyl]benzene and (E,E)-1,4-bis(2,3,4-trimethoxyphenyl)buta-1,3-diene

Sopková-de Oliveira Santos, J. — 2009-06-06

The stilbene derivative 1,2,3-trimethoxy-4-[(E)-2-phenylvinyl]benzene, C17H18O3, (I), and its homocoupling co-product (E,E)-1,4-bis(2,3,4-trimethoxyphenyl)buta-1,3-diene, C22H26O6, (II), both have double bonds in trans conformations in their conjugated linkages. In the structure of stilbene (I), the aromatic rings deviate significantly from coplanarity, in contrast with coproduct (II), the core of which is rigorously planar. The deviation in stilbene (I) seems to be driven by intermolecular electrostatic interactions. Diene (II) sits on a crystallographic inversion centre, which bisects the conjugated linkage.

Structural effects on the solid-state photodimerization of 2-pyridone derivatives in inclusion compounds

Telzhensky, M. — 2009-06-06

The structures of six crystalline inclusion compounds between various host molecules and three guest molecules based on the 2-pyridone skeleton are described. The six compounds are 1,1′-biphenyl-2,2′-dicarboxylic acid–2-pyridone (1/2), C14H10O4·2C5H5NO, (I–a), 1,1′-biphenyl-2,2′-dicarboxylic acid–4-methyl-2-pyridone (1/2), C14H10O4·2C6H7NO, (I–c), 1,1′-biphenyl-2,2′-dicarboxylic acid–6-methyl-2-pyridone (1/2), C14H10O4·2C6H7NO, (I–d), 1,1,6,6-tetraphenyl-2,4-hexadiyne-1,6-diol–1-methyl-2-pyridone (1/2), C30H22O2·2C6H7NO, (II–b), 1,1,6,6-tetraphenyl-2,4-hexadiyne-1,6-diol–4-methy-2-pyridone (1/2), C30H22O2·2C6H7NO, (II–c), and 4,4′,4′′-(ethane-1,1,1-triyl)triphenol–6-methyl-2-pyridone–water (1/3/1), C20H18O3·3C6H7NO·H2O, (III–d). In two of the compounds, (I–a) and (I–d), the host molecules lie about crystallographic twofold axes. In two other compounds, (II–b) and (II–c), the host molecules lie across inversion centers. In all cases, the guest molecules are hydrogen bonded to the host molecules through O—H...O=C hydrogen bonds [the range of O...O distances is 2.543 (2)–2.843 (2) Å. The pyridone moieties form dimers through N—H...O=C hydrogen bonds in five of the compounds [the range of N...O distances is 2.763 (2)–2.968 (2) Å]. In four compounds, (I–a), (I–c), (I–d) and (II–c), the molecules are arranged in extended zigzag chains formed via host–guest hydrogen bonding. In five of the compounds, the guest molecules are arranged in parallel pairs on top of each other, related by inversion centers. However, none of these compounds underwent photodimerization in the solid state upon irradiation. In one of the crystalline compounds, (III–d), the guest molecules are arranged in stacks with one disordered molecule. The unsuccessful dimerization is attributed to the large interatomic distances between the potentially reactive atoms [the range of distances is 4.027 (4)–4.865 (4) Å] and to the bad overlap, expressed by the lateral shift between the orbitals of these atoms [the range of the shifts from perfect overlap is 1.727 (4)–3.324 (4) Å]. The bad overlap and large distances between potentially photoreactive atoms are attributed to the hydrogen-bonding schemes, because the interactions involved in hydrogen bonding are stronger than those in π–π interactions.

2-Methoxy-3-methyl-6-oxo-4-(2,3,4-tri-O-acetyl-β-d-xylopyranosylamino)-1,6-dihydropyrimidine-5-carbaldehyde 0.065-hydrate and 2-methylsulfanyl-6-oxo-4-(2,3,4-tri-O-acetyl-β-d-xylopyranosylamino)-1,6-dihydropyrimidine-5-carbaldehyde: hydrogen-bonded structures in one or three dimensions

Cobo, J. — 2009-06-06

The organic components of 2-methoxy-3-methyl-6-oxo-4-(2,3,4-tri-O-acetyl-β-d-xylopyranosylamino)-1,6-dihydropyrimidine-5-carbaldehyde 0.065-hydrate, C18H23N3O10·0.065H2O, (I), which crystallizes with Z′ = 2 in the space group P212121, are linked into a three-dimensional framework structure by a combination of four C—H...O hydrogen bonds. In 2-methylsulfanyl-6-oxo-4-(2,3,4-tri-O-acetyl-β-d-xylopyranosylamino)-1,6-dihydropyrimidine-5-carbaldehyde, C17H21N3O9S, (II), where the pyrimidine fragment is disordered with two different conformations for the methylsulfanyl substituent, molecules are linked into chains of rings by a combination of N—H...O and C—H...O hydrogen bonds.

Conformational and configurational disorder in 6-(3,4,5-trimethoxyphenyl)-6,7-dihydro-5H-1,3-dioxolo[4,5-g]quinolin-8(5H)-one and 6-(1,3-benzodioxol-5-yl)-6,7-dihydro-5H-1,3-dioxolo[4,5-g]quinolin-8-one: a hydrogen-bonded chain of rings and π-stacked hydrogen-bonded chains

Cuervo, P. — 2009-06-06

In 6-(3,4,5-trimethoxyphenyl)-6,7-dihydro-5H-1,3-dioxolo[4,5-g]quinolin-8(5H)-one, C19H19NO6, (I), the six-membered heterocyclic ring adopts a conformation intermediate between envelope and half-chair forms; it is disordered over two enantiomeric configurations, with occupancies of 0.879 (3) and 0.121 (3), leading to positional disorder of the 3,4,5-trimethoxyphenyl unit. In 6-(1,3-benzodioxol-5-yl)-6,7-dihydro-5H-1,3-dioxolo[4,5-g]quinolin-8-one, C17H13NO5, (II), the molecules are similarly disordered, with occupancies of 0.866 (4) and 0.134 (4). The molecules in (I) are linked by one three-centre N—H...(O)2 hydrogen bond and one two-centre C—H...O hydrogen bond to form a complex chain of rings whose formation is reinforced by two independent aromatic π–π stacking interactions. In (II), a single N—H...O hydrogen bond links the molecules into a simple chain, and pairs of chains are linked by a single aromatic π–π stacking interaction.

`Segmented' crystals solved using synchrotron radiation: (2S,3R,4S,5R)-4-(10,10-dimethyl-3,3-dioxo-3λ6-thia-4-azatricyclo[5.2.1.01,5]decan-4-ylcarbonyl)-2,6-diphenylperhydropyrrolo[3,4-c]pyrrole-1,3-dione

Gainsford, G.J. — 2009-06-13

The title compound, C29H31N3O5S, forms needle-shaped `segmented' crystals, thereby inhibiting successful single-crystal data collection using conventional laboratory facilities. One crystallite of dimensions 0.15 × 0.03 × 0.01 mm yielded sufficent single-crystal diffraction data on the Australian Synchrotron PX1 beamline. The two independent molecules in the asymmetric unit are nearly superimposable and show only minor conformational deviations from closely related compounds. The molecules pack using one N—H...O hydrogen bond and several phenyl C—H...O(=S), phenyl C—H...O(=C) and methylene C—H...O(=C) hydrogen bonds and weak C—H...π interactions.

Dipolar S=O...C=O and C—H...O interactions in the molecular organization of 4,6-di-O-acetyl-2-O-tosyl-myo-inositol 1,3,5-orthoesters

Manoj, K. — 2009-06-13

In the absence of conventional hydrogen bonding, the molecules of 4,6-di-O-acetyl-2-O-tosyl-myo-inositol 1,3,5-orthoformate, C18H20O10S, (I), and 4,6-di-O-acetyl-2-O-tosyl-myo-inositol 1,3,5-orthobenzoate, C24H24O10S, (II), are associated via C—H...O interactions. Molecules of (II) are additionally linked via dipolar S=O...C=O contacts. It is interesting to note that the sulfonyl O atom involved in the dipolar S=O...C=O contacts does not take part in any other interaction, indicating the competitive nature of this contact relative to the weak hydrogen-bonding interactions.

Hydrogen-bonded network in the trichloroacetate salts of 2-amino-5-chloropyridinium and 2-methyl-5-nitroanilinium monohydrate

Janczak, J. — 2009-06-13

In the crystal structures of 2-amino-5-chloropyridinium trichloroacetate, C5H6ClN2+·C2Cl3O2−, (I), and 2-methyl-5-nitroanilinium trichloroacetate monohydrate, C7H9N2O2+·C2Cl3O2−·H2O, (II), the protonated planar 2-amino-5-chloropyridinium [in (I)] and 2-methyl-5-nitroanilinium [in (II)] cations interact with the oppositely charged trichloroacetate anions to form hydrogen-bonded one-dimensional chains in (I) and, together with water molecules, a three-dimensional network in (II). The crystals of (I) exhibit nonlinear optical properties. The second harmonic generation efficiency in relation to potassium dihydrogen phosphate is 0.77. This work demonstrates the usefulness of trichloroacetic acid in crystal engineering for obtaining new materials for nonlinear optics.

4-Benzoyl-3,4-dihydro-2H-1,4-benzoxazine-2-carbonitrile: refinement using a multipolar atom model

Ejsmont, K. — 2009-06-13

The structural model for the title compound, C16H12N2O2, was refined using a multipolar atom model transferred from an experimental electron-density database. The refinement showed some improvements of crystallographic statistical indices when compared with a conventional spherical neutral-atom refinement. The title compound adopts a half-chair conformation. The amide N atom lies almost in the plane defined by the three neighbouring C atoms. In the crystal structure, molecules are linked by weak intermolecular C—H...O and C—H...π hydrogen bonds.

A structural systematic study of four isomers of difluoro-N-(3-pyridyl)benzamide

McMahon, J. — 2009-06-27

The four isomers 2,4-, (I), 2,5-, (II), 3,4-, (III), and 3,5-difluoro-N-(3-pyridyl)benzamide, (IV), all with formula C12H8F2N2O, display molecular similarity, with interplanar angles between the C6/C5N rings ranging from 2.94 (11)° in (IV) to 4.48 (18)° in (I), although the amide group is twisted from either plane by 18.0 (2)–27.3 (3)°. Compounds (I) and (II) are isostructural but are not isomorphous. Intermolecular N—H...O=C interactions form one-dimensional C(4) chains along [010]. The only other significant interaction is C—H...F. The pyridyl (py) N atom does not participate in hydrogen bonding; the closest H...Npy contact is 2.71 Å in (I) and 2.69 Å in (II). Packing of pairs of one-dimensional chains in a herring-bone fashion occurs via π-stacking interactions. Compounds (III) and (IV) are essentially isomorphous (their a and b unit-cell lengths differ by 9%, due mainly to 3,4-F2 and 3,5-F2 substitution patterns in the arene ring) and are quasi-isostructural. In (III), benzene rotational disorder is present, with the meta F atom occupying both 3- and 5-F positions with site occupancies of 0.809 (4) and 0.191 (4), respectively. The N—H...Npy intermolecular interactions dominate as C(5) chains in tandem with C—H...Npy interactions. C—H...O=C interactions form R22(8) rings about inversion centres, and there are π–π stacks about inversion centres, all combining to form a three-dimensional network. By contrast, (IV) has no strong hydrogen bonds; the N—H...Npy interaction is 0.3 Å longer than in (III). The carbonyl O atom participates only in weak interactions and is surrounded in a square-pyramidal contact geometry with two intramolecular and three intermolecular C—H...O=C interactions. Compounds (III) and (IV) are interesting examples of two isomers with similar unit-cell parameters and gross packing but which display quite different intermolecular interactions at the primary level due to subtle packing differences at the atom/group/ring level arising from differences in the peripheral ring-substitution patterns.

Three solvates of a bis-mesoionic fluorescent yellow pigment

Brüning, J. — 2009-06-27

p-Phenylenebis(2-oxo-3-phenyl-1,2-dihydropyrido[1,2-a]pyrimidin-5-ium-4-olate), C34H22N4O4, is a bis-mesoionic yellow pigment that shows fluorescence in the solid state. During a polymorph screening, single crystals of three solvates were grown and their crystal structures determined. Solvent-free crystals were not obtained. A solvate with N-methylpyrrolidone (NMP) and propan-2-ol, C34H22N4O4·2C5H9NO·C3H8O, (Ia), and an NMP trisolvate, C34H22N4O4·3C5H9NO, (Ib), crystallize with pigment molecules on inversion centres. The NMP/propan-2-ol mixed solvate (Ia) forms O—H...O hydrogen bonds between the different solvent molecules. In both structures, at least one of the solvent molecules is disordered. A third solvate structure, C34H22N4O4·0.5C5H9NO·C4H10O, (Ic), was obtained by crystallization from NMP and butan-1-ol. In this case, there are two symmetry-independent pigment molecules, both situated on inversion centres. The solvent molecules are heavily disordered and their contribution to the scattering was suppressed. This solvate displays a channel structure, whereas the other two solvates form layer structures.

A pair of diastereomeric 1:1 salts of (S)- and (R)-2-methylpiperazine with (2S,3S)-tartaric acid

Katagiri, H. — 2009-06-30

The structures of diastereomeric pairs consisting of (S)- and (R)-2-methylpiperazine with (2S,3S)-tartaric acid are both 1:1 salts, namely (S)-2-methylpiperazinium (2S,3S)-tartrate dihydrate, C5H14N22+·C4H4O62−·2H2O, (I), and (R)-2-methylpiperazinium (2S,3S)-tartrate dihydrate, C5H14N22+·C4H4O62−·2H2O, (II), which reveal the formation of well defined ammonium carboxylate salts linked via strong intermolecular hydrogen bonds. Unlike the situation in the more soluble salt (II), the alternating columns of tartrate and ammonium ions of the less soluble salt (I) are packed neatly in a grid around the a axis, which incorporates water molecules at regular intervals. The increased efficiency of packing for (I) is evident in its lower `packing coefficient', and the hydrogen-bond contribution is stronger in the more soluble salt (II).

4-Aminopyridinium 4-aminobenzoate dihydrate and 4-aminopyridinium nicotinate

Jebas, S.R. — 2009-06-30

In the title compounds, 4-aminopyridinium 4-aminobenzoate dihydrate, C7H6NO2−·C5H7N2+·2H2O, (I), and 4-aminopyridinium nicotinate, C5H7N2+·C6H4NO2−, (II), the aromatic N atoms of the 4-aminopyridinium cations are protonated. In (I), the asymmetric unit is composed of two 4-aminopyridinium cations, two 4-aminobenzoate anions and four water molecules, and the compound crystallizes in a noncentrosymmetric space group. The two sets of independent molecules of (I) are related by a centre of symmetry which is not part of the space group. In (I), the protonated pyridinium ring H atoms are involved in bifurcated hydrogen bonding with carboxylate O atoms to form an R12(4) ring motif. The water molecules link the ions to form a two-dimensional network along the (10\overline{1}) plane. In (II), an intramolecular bifurcated hydrogen bond generates an R12(4) ring motif and inter-ion hydrogen bonding generates an R42(16) ring motif. The packing of adduct (II) is consolidated via N—H...O and N—H...N hydrogen bonds to form a two-dimensional network along the (10\overline{2}) plane.