Di-aqua-bis-(ethyl-enedi-amine-κ(2) N,N')copper(II) bis-(sulfamerazinate).

The asymmetric unit of the title compound, [Cu(C2H8N2)2(H2O)2](C11H11N4O2S)2, contains one sulfamerazinate anion in a general position and one half-cation that is located on a center of inversion. The Cu(II) cation shows a strong Jahn-Teller distortion. It is coordinated by four N atoms of two ethyl-enedi-amine ligands in the basal plane and two O atoms at much longer distances in the axial positions in a bipyramidal coordination. In the crystal, the building blocks are connected by N-H⋯N, O-H⋯N, N-H⋯O and O-H⋯O hydrogen bonding into a two-dimensional network parallel to (001).

Cytosinium hydrogen selenite.

In the crystal structure of the title salt, C4H6N3O(+)·HSeO3 (-), systematic name 6-amino-2-methyl-idene-2,3-di-hydro-pyrim-idin-1-ium hydrogen selenite, the hydrogenselenite anions and the cytosinium cations are linked via N-H⋯O, N-H⋯Se, O-H⋯O, O-H··Se and C-H⋯O hydrogen bonds, forming a three-dimensional framework.

Solvent effects of N-nitroso, N-(2-chloroethyl), N',N'-dibenzylsulfamid and its copper(II) and cobalt(II) complexes: fluorescence studies.

The structure of N-nitroso, N-(2-chloroethyl), N',N'-dibenzylsulfamid (CENS) was established by X-ray crystallography. The atomic coordinates, factors of isotropic thermal agitation, bond lengths and valence angles were determined. The solvent effects on the electronic absorption and fluorescence spectra of CENS were investigated at room temperature. The effects of solvent polarity and of hydrogen bonding were interpreted by means of linear solvation energy relationships (LSERs). Multiple linear regression analysis indicated that the hydrogen donation properties of the solvent play an important role in determining the position of the absorption maximum, while the classical polarity of the medium is the only dominating parameter in determining the emission maximum and the Stokes' shift. Complexation of the investigated compound by two different transition metal ions was studied. Fluorescence measurements show that fluorescence quenching by cobalt(II) is more important than that by copper(II). This phenomenon can be attributed to good stereo-structural matching between the electronic configuration of the Co(2+) ion and the active site distribution of CENS in aqueous solution.

Hydrogen bonding in 1-carb-oxy-propanaminium nitrate.

There are two crystallographically independent cations and two anions in the asymmetric unit of the title compound, C(4)H(5)NO(2) (+)·NO(3) (-). In the crystal, the 1-carb-oxy-propanaminium cations and nitrate anions are linked to each other through strong N-H⋯O and O-H⋯O hydrogen bonds, forming a three-dimensional complex network. C-H⋯O inter-actions also occur.

trans-Diaqua-bis-(dl-valinato-κN,O)nickel(II).

In the title complex, [Ni(C(5)H(9)NO(2))(2)(H(2)O)(2)], the Ni(II) atom, located on a centre of inversion, is trans-coordinated by two O atoms and two N atoms from d-bidentate valine and l-bidentate valine ligands and two water O atoms in an octa-hedral geometry. In the crystal, the discrete mononuclear units are linked into a three-dimensional network via O-H⋯O and N-H⋯O hydrogen bonds. C-H⋯O inter-actions are also observed.

Anilinium hydrogen sulfate.

The asymmetric unit of the title compound, C(6)H(8)N(+)·HSO(4) (-), contains two cations and two anions which are linked to each other through N-H⋯O hydrogen bonds, formed by all H atoms covalently bonded to the N atoms. In addition, strong O-H⋯O anion-anion hydrogen-bond inter-actions are also observed.

(4S)-4-Benzyl-N-{[(4S)-4-benzyl-2-oxo-1,3-oxazolidin-3-yl]sulfon-yl}-2-oxo-1,3-oxazolidine-3-carboxamide.

The title compound, C(21)H(21)N(3)O(7)S, contains an oxazolidinone ring and a sulfonamide group, both characteristic for biologically and pharrmaceutically active compounds. Both stereogenic centres reveal an S absolute configuration. The two oxazolidinone rings are in an envelope conformation with the methyl-ene carbon flap atoms deviating by 0.428 (1) and 0.364 (2) Šfrom the best least-square planes formed by the four other ring atoms. An intra-molecular N-H⋯O hydrogen bond contributes to the folded conformation of the mol-ecule. In the crystal, weak inter-molecular C-H⋯O inter-actions connect the mol-ecules into helices along the the twofold screw axes.

Cytosinium-hydrogen maleate-cytosine (1/1/1).

The title organic salt, C(4)H(6)N(3)O(+)·C(4)H(3)O(4) (-)·C(4)H(5)N(3)O, was synthesized from cytosine base and maleic acid. An intra-molecular O-H⋯O hydrogen bond occurs in the hydrogen maleate anion. The crystal packing is stabilized by inter-molecular N-H⋯O, N-H⋯N and C-H⋯O hydrogen bonds, giving rise to a nearly planar two-dimensional network parallel to (101).

4-Methyl-anilinium nitrate.

The asymmetric unit of the title compound, C(7)H(10)N(+)·NO(3) (-), consists of a 4-methyl-anilinium cation protonated at the amino group and a nitrate anion. In the crystal, anions and cations are linked through N-H⋯O and N-H⋯(O,O) hydrogen bonds, buiding a corrugated layer structure parallel to (001).

Hydrogen bonding in 2-carboxy-anilinium dihydrogen phosphite at 100†K.

The title compound, C(7)H(8)NO(2) (+)·H(2)PO(3) (-), is formed from alternating layers of organic cations and inorganic anions stacked along the a-axis direction. They are associated via O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonding, giving rise to two different R(2) (2)(8) graph-set motifs and generating a three-dimensional network.

Hydrogen bonding in cytosinium dihydrogen phosphite.

In the title compound, C(4)H(8)N(3)O(4)P(+)·H(2)PO(3) (-), the cytosine mol-ecule is monoprotonated and the phospho-ric acid is in the monoionized state. Strong hydrogen bonds, dominated by N-H⋯O inter-actions, are responsible for cohesion between the organic and inorganic layers and maintain the stability of this structure.

Creatinium perchlorate.

The title compound, C(4)H(8)N(3)O(+)·ClO(4) (-), is built up from creatininium cations and perchlorate anions. Crystal cohesion and perchlorate stability are ensured by N-H⋯O hydrogen bonds that together with weak C-H⋯O inter-actions build up a three-dimensional network.

Nonlinear optical organic-inorganic crystals: synthesis, structural analysis and verification of harmonic generation in tri-(o-chloroanilinium nitrate).

The structural and nonlinear optical properties of a new anilinium hybrid crystal of chemical formula (C6H7NCl+·NO3-)3 have been investigated. The crystal structure was determined from single-crystal X-ray diffraction measurements performed at a temperature of 100 K which show that the compound crystallizes in a noncentrosymmetric space group (Pna21). The structural analysis was coupled with Hirshfeld surface analysis to evaluate the contribution of the different intermolecular interactions to the formation of supramolecular assemblies in the solid state that exhibit nonlinear optical features. This analysis reveals that the studied compound is characterized by a three-dimensional network of hydrogen bonds and the main contributions are provided by the O...H, C...H, H...H and Cl...H interactions, which alone represent ∼85% of the total contributions to the Hirshfeld surfaces. It is noteworthy that the halogen...H contributions are quite comparable with those of the H...H contacts. The nonlinear optical properties were investigated by nonlinear diffuse femtosecond-pulse reflectometry and the obtained results were compared with those of the reference material LiNbO3. The hybrid crystals exhibit notable second (SHG) and third (THG) harmonic generation which confirms its polarity is generated by the different intermolecular interactions. These measurements also highlight that the THG signal of the new anilinium compound normalized to its SHG counterpart is more pronounced than for LiNbO3.

Ammonium tris-(tetra-ethyl-ammonium) hexa-cosa-oxidoocta-molybdate.

The structure of the title compound, NH(4)(C(8)H(20)N)(3)[Mo(8)O(26)], is built up by discrete cations and anions, with two formula units in the asymmetric unit. The ß-octa-molybdate anions are linked to the ammonium cations via N-H⋯O hydrogen bonding involving terminal oxide groups and to the tetra-ethyl-ammonium cations via weak C-H⋯O inter-actions.

Intermolecular interactions of proton transfer compounds: synthesis, crystal structure and Hirshfeld surface analysis.

Three new proton transfer compounds, [2-ammonio-5-methylcarboxybenzene perchlorate (1), (C8H10NO2(+)·ClO4(-)), 4-(ammoniomethyl)carboxybenzene nitrate (2), (C8H10NO2(+)·NO3(-)), and 4-(ammoniomethyl)carboxybenzene perchlorate (3), (C8H10NO2(+)·ClO4(-))], have been synthesized, their IR modes of vibrations have been assigned and their crystal structures studied by means of single-crystal X-ray diffraction. Their asymmetric units consist of one cation and one anion for both compounds (1) and (2). However, the crystal structure of compound (3) is based on a pair of cations and a pair of anions in its asymmetric unit. The three-dimensional Hirshfeld surface analysis and the two-dimensional fingerprint maps revealed that the three structures are dominated by H...O/O...H and H...H contacts. The strongest hydrogen-bonding interactions are associated with O-H...O and N-H...O constituting the highest fraction of approximately 50%, followed by those of the H...H type contributing 20%. Other close contacts are also present, including weak C...H/H...C contacts (with about 10%).

Studies of Copper Complexes Displaying N(3)S Coordination as Models for Cu(B) Center of Dopamine beta-Hydroxylase and Peptidylglycine alpha-Hydroxylating Monooxygenase.

We describe the studies of new copper complexes [MeSPY2]CuPF(6), 2, and [MeSPY2]Cu(ClO(4))(2).CH(3)CN, 3, as models for the Cu(B) center of dopamine beta-hydroxylase and peptidylglycine alpha-hydroxylating monooxygenase. The structure of [MeSPY2]Cu(ClO(4))(2).CH(3)CN, 3, has been established by X-ray crystallography. The copper coordination exhibits a square pyramidal geometry where the equatorial plane is occupied by the SCH(3) group and three nitrogen atoms (tertiary amine, one pyridine, and acetonitrile solvent), whereas the axial position binds the second pyridine. Using FEFF calculations and multiscattering interaction, EXAFS refinements show that the SMe group lies in the coordination sphere of copper complexes [MeSPY2]CuPF(6), 2, and [MeSPY2]Cu(ClO(4))(2).CH(3)CN, 3. While [MeSPY2]CuPF(6), 2, reacts with dioxygen in dichloromethane without oxidation of the ligand, we observed an oxidation of the sulfide ligand when [MeSPY2]Cu(ClO(4))(2).CH(3)CN, 3, reacts with hydrogen peroxide in methanol. Considering results, we propose that Met(314), crucial for DBH and PHM activity, could be the site of the H(2)O(2) (or ascorbate) inactivation by oxidation to the sulfoxide group.

The structural properties of a noncentrosymmetric polymorph of 4-aminobenzoic acid.

The crystal structure of a polymorph of 4-aminobenzoic acid (PABA), C7H7NO2, at 100 K is noncentrosymmetric, as opposed to centrosymmetric in the structures of the other known polymorphs. The two crystallographically independent PABA molecules form pseudocentrosymmetric O-H...O hydrogen-bonded dimers that are further linked by N-H...O hydrogen bonds into a three-dimensional network. The benzene rings stack in the b direction. The CO2 moieties are bent out slightly from the benzene ring plane.

A comparative study of two polymorphs of L-aspartic acid hydrochloride.

Two polymorphs of L-aspartic acid hydrochloride, C4H8NO4(+)·Cl(-), were obtained from the same aqueous solution. Their crystal structures have been determined from single-crystal data collected at 100 K. The crystal structures revealed three- and two-dimensional hydrogen-bonding networks for the triclinic and orthorhombic polymorphs, respectively. The cations and anions are connected to one another via N-H···Cl and O-H···Cl interactions and form alternating cation-anion layer-like structures. The two polymorphs share common structural features; however, the conformations of the L-aspartate cations and the crystal packings are different. Furthermore, the molecular packing of the orthorhombic polymorph contains more interesting interactions which seems to be a favourable factor for more efficient charge transfer within the crystal.

Tautomerism and hydrogen bonding in guaninium phosphite and guaninium phosphate salts.

The crystal structures of three similar guaninium salts, guaninium monohydrogenphosphite monohydrate, C(5)H(6)N(5)O(+).H(2)O(3)P(-).H(2)O, guaninium monohydrogenphosphite dihydrate, C(5)H(6)N(5)O(+).H(2)O(3)P(-).2H(2)O, and guaninium dihydrogenmonophosphate monohydrate, C(5)H(6)N(5)O(+).H(2)O(4)P(-).H(2)O, are described and compared. The crystal structures have been determined from accurate single-crystal X-ray data sets collected at 100 (2) K. The two phosphite salts are monoclinic, space group P2(1)/c, with different packing and the monophosphate salt is also monoclinic, space group P2(1)/n. An investigation of the hydrogen-bond network in these guaninium salts reveals the existence of two ketoamine tautomers, the N9H form and an N7H form.

Isostructural phase transition in m-carboxyphenylammonium monohydrogenphosphite.

Crystals of m-carboxyphenylammonium monohydrogenphosphite, C7H8NO2+.H2PO3- (m-CPAMP), space group P2(1)/c, grown from aqueous solution undergo a reversible first-order single-crystal phase transition at Tc = 246 (2) K with a hysteresis of 3.6 K. The thermal behaviour of the sample was characterized by differential scanning calorimetry (DSC) experiments. Variations of the unit-cell parameters versus temperature between 100 and 320 K are reported. The transition from the higher-temperature phase (HTP) to the lower-temperature phase (LTP) is characterized by a unit-cell volume contraction of 1.77%. The average structure and unit-cell packing of m-CPAMP at lower temperature (100 K) are reported from accurate X-ray data sets and compared with those of the higher-temperature phase (293 K) in order to investigate the mechanism of the phase transition. The reciprocal lattice reconstruction showed a few very weak satellite reflections which will be discussed in a forthcoming paper.