Syntheses, crystal structures and Hirshfeld surface analysis of three salts of 1-(4-nitro-phenyl)-piperazine

The structures and Hirshfeld surface analysis of three salts of 1-(4-nitro-phenyl)-piperazine are discussed. In 4-(4-nitro-phen-yl)piperazin-1-ium salicylate (C₁₀H₁₄N₃O₂ ⁺·C₇H₅O₃ ^-), there are strong hydrogen bonds between cation and anion and the 4-nitro-phenyl substituent occupies an equatorial position in the piperazinium ring. The cation and anion are linked together by supra-molecular inter-actions [graph-set notation of hydrogen bonding (6) propagating in the a-axis direction]. Additionally, there is π-π stacking involving the salicylate anion and the piperazinium cation in adjacent asymmetric units as well as a C-H⋯π inter-action between a hydrogen atom on the piperazine ring and the phenyl ring within the salicyclate anion. In bis-[4-(4-nitro-phen-yl)piperazin-1-ium] bis-(4-fluoro-benzoate) trihydrate (2C₁₀H₁₄N₃O₂ ⁺·2C₇H₄FO₂ ^-·3H₂O), there are two cations, two anions, and three water mol-ecules of solvation in the asymmetric unit, all linked by hydrogen bonds [graph-set notation of hydrogen bonding R ² ₂(20) between adjacent cations and R ³ ₃(9) between a cation and its adjacent anion]. In the anion, the 4-nitro-phenyl ring occupies an axial substitution position in the piperazinium ring, which is relatively rare. Within the asymmetric unit, the phenyl groups in the cations show an offset π-π inter-action. Additionally, there is a C-H⋯π inter-action between a hydrogen atom on the phenyl ring within a cation and the phenyl ring within an anion. In 4-(4-nitro-phen-yl)piperazin-1-ium 3,5-di-nitro-benzoate (C₁₀H₁₄N₃O₂ ⁺·C₇H₄N₂O₆ ^-), there is a strong N-H⋯O hydrogen bond linking the cation and anion and the 4-nitro-phenyl ring occupies an axial substitution position in the piperazinium ring, as seen in the previous structure. In the crystal, the cation and the anion form a complex three-dimensional hydrogen-bonded array involving R ² ₂(8), R ⁴ ₄(12) and R ⁴ ₄(20) rings propogating in the a-axis direction. The nitro-phenyl group is disordered with occupancies of 0.806 (10) and 0.194 (10).

The structures of eleven (4-phen-yl)piperazinium salts containing organic anions

Eleven (4-phen-yl)piperazinium salts containing organic anions have been prepared and structurally characterized, namely, 4-phenyl-piperazin-1-ium 4-fluoro-benzoate monohydrate, C₁₀H₁₅N₂ ⁺·C₇H₄FO₂ ^-·H₂O, 1; 4-phenyl-piperazin-1-ium 4-bromo-benzoate monohydrate, C₁₀H₁₅N₂ ⁺·C₇H₄BrO₂ ^-·H₂O, 3; 4-phenyl-piperazin-1-ium 4-iodo-benzoate, C₁₀H₁₅N₂ ⁺·C₇H₄IO₂ ^-, 4; 4-phenyl-piperazin-1-ium 4-nitro-benzoate, C₁₀H₁₅N₂ ⁺·C₇H₄NO₄ ^-, 5; 4-phenyl-piperazin-1-ium 3,5-di-nitro-salicylate, C₁₀H₁₅N₂ ⁺·C₇H₃N₂O₇ ^-, 6; 4-phenyl-piperazin-1-ium 3,5-di-nitro-benzoate, C₁₀H₁₅N₂ ⁺·C₇H₃N₂O₆ ^-, 7; 4-phenyl-piperazin-1-ium picrate, C₁₀H₁₅N₂ ⁺·C₆H₂N₃O₇ ^-, 8; 4-phenyl-piperazin-1-ium benzoate monohydrate, C₁₀H₁₅N₂ ⁺·C₇H₅O₂ ^-·H₂O, 9; 4-phenyl-piperazin-1-ium p-toluene-sulfonate, C₁₀H₁₅N₂ ⁺·C₇H₇O₃S^-, 10; 4-phenyl-piperazin-1-ium tartarate monohydrate, C₁₀H₁₅N₂ ⁺·C₄H₅O₆ ^-·H₂O, 11; and 4-phenyl-piperazin-1-ium fumarate, C₁₀H₁₅N₂ ⁺·C₄H₃O₄ ^-, 12. Compounds 1 and 3-12 are all 1:1 salts with the acid proton transferred to the phenyl-piperaizine basic N atom (the secondary amine) with the exception of 3 where there is disorder in the proton position with it being 68% attached to the base and 32% attached to the acid. Of the structures with similar stoichiometries only 3 and 9 are isomorphous. The 4-phenyl substituent in all cases occupies an equatorial position except for 12 where it is in an axial position. The crystal chosen for structure 7 was refined as a non-merohedral twin. There is disorder in 5, 6, 10 and 11. For both 5 and 6, a nitro group is disordered and was modeled with two equivalent orientations with occupancies of 0.62 (3)/0.38 (3) and 0.690 (11)/0.310 (11), respectively. For 6, 10 and 11, this disorder is associated with the phenyl ring of the phenyl-piperazinium cation with occupancies of 0.687 (10)/0.313 (10), 0.51 (7)/0.49 (7) and 0.611 (13)/389 (13), respectively. For all salts, the packing is dominated by the N-H⋯O hydrogen bonds formed by the cation and anion. In addition, several structures contain C-H⋯π (1, 3, 4, 8, 9, 10, and 12) and aromatic π-π stacking inter-actions (6 and 8) and one structure (5) contains a -NO₂⋯π inter-action. For all structures, the Hirshfeld surface fingerprint plots show the expected prominent spikes as a result of the N-H⋯O and O-H⋯O hydrogen bonds.

Synthesis and crystal structures of 1-benzoyl-4-(4-nitrophenyl)piperazine and 1-(4-bromobenzoyl)-4-phenylpiperazine at 90 K

The syntheses and low-temperature (90 K) crystal structures of 1-benzoyl-4-(4-nitro­phen­yl)piperazine and 1-(4-bromo­benzo­yl)phenyl­piperazine are presented.

Synthesis and crystal structures of 1-benzoyl-4-(4-nitro­phen­yl)piperazine, C₁₇H₁₇N₃O₃, (I) and 1-(4-bromo­benzo­yl)-4-phenyl­piperazine, C₁₇H₁₇BrN₂O, (II) are described. Compounds I and II crystallize in the ortho­rhom­bic and monoclinic crystal systems with space groups Pna2₁ (Z′ = 2, I) and P2₁ (Z′ = 1, II), respectively. The crystal of II was a two-component aggregate, treated as a ‘twin’ for data-acquisition purposes. There are no conventional hydrogen bonds in either I or II, but there are weaker C—H⋯O contacts. Each mol­ecule consists of a central piperazine ring in a chair conformation, with either benzoyl and nitro­phenyl (I) or 4-bromo­benzoyl and phenyl (II) groups attached to different nitro­gen atoms of the piperazine. The various atom–atom contact coverages as qu­anti­fied by Hirshfeld surface analysis fingerprint plots are given.

Synthesis and crystal structure of topiramate azidosulfate at 90 K and 298 K

The synthesis, crystal structure, absolute configuration, spectroscopic and spectrometric details of topiramate azido­sulfate, a precursor to the anti-convulsant drug topiramate, are presented.

The low (90 K) and room (298 K) temperature crystal structures of topiramate azido­sulfate [systematic name 2,3:4,5-bis-O-(1-methyl­ethyl­idene)-β-d-fructo­pyran­ose azido­sulfate], C₁₂H₁₉N₃O₈S, an inter­mediate in the synthesis of the anti-convulsant drug topiramate, are described. Topiramate azido­sulfate (I) finds use as a reference impurity standard for topiramate. A modified synthesis and some spectroscopic details are also presented.

Isopropyl 4-aminobenzoate

The title compound crystallizes with two mol­ecules in the asymmetric unit, which form double chains in the crystal linked by N—H⋯O and N—H⋯N hydrogen bonds.

The title compound, C₁₀H₁₃NO₂, crystallizes with two mol­ecules (A and B) in the asymmetric unit. For A, the dihedral angle between the plane of the phenyl ring and the i-propyl substituent is 65.4 (3)° while for B this angle is 67.8 (3)°. In the crystal, the mol­ecules are linked by N—H⋯O and N—H⋯N hydrogen bonds to generate double chains propagating in the [100] direction.

Synthesis and crystal structure of ebastinium hydrogen fumarate

Crystals of the title salt are twinned by pseudo-merohedry and the structure shows extensive disorder. A strong N—H⋯O hydrogen bond links the cation and the anion and the anions are linked into [010] chains by O—H⋯O hydrogen bonds.

The structure of ebastinium hydrogen fumarate {systematic name: 1-[4-(4-tert-butyl­phen­yl)-4-oxobut­yl]-4-(di­phenyl­meth­oxy)piperidin-1-ium (E)-3-carb­oxy-1-hy­droxy­prop-2-en-1-olate}, C₃₂H₄₀NO₂⁺·C₄H₃O₄⁻, a 1:1 salt formed in the reaction between ebastine and fumaric acid is presented. All examined crystals were found to be twinned by pseudo-merohedry. The structure is extensively disordered, with over half (20 out of 35) its non-hydrogen atoms modelled as lying over two sets of sites. In the crystal, cation–anion pairs are linked by a strong N—H⋯O hydrogen bond [N⋯O = 2.697 (11) Å]. These units inter­act via weaker C—H⋯O and C—H⋯π contacts to form layers lying parallel to the bc plane. The hydrogen fumarate anions are linked by a very short O—H⋯O hydrogen bond [O⋯O = 2.5402 (17) Å], augmented by weak C—H⋯O contacts into pairs of R²₂(6) ring motifs to form chains that extend parallel to the b-axis direction. Comparisons to similar crystal structures are presented.

Crystal-structure studies of 4-phenylpiperazin-1-ium 4-ethoxybenzoate monohydrate, 4-phenylpiperazin-1-ium 4-methoxybenzoate monohydrate, 4-phenylpiperazin-1-ium 4-methylbenzoate monohydrate and 4-phenylpiperazin-1-ium trifluoroacetate 0.12-hydrate

In this study, four new piperazinium salts, namely, 4-phenylpiperazin-1-ium 4-ethoxybenzoate monohydrate, C9H9O3·C10H15N2·H2O (I); 4-phenylpiperazin-1-ium 4-methoxybenzoate monohydrate, C10H15N2·C8H7O3·H2O (II); 4-phenylpiperazin-1-ium 4-methylbenzoate monohydrate, C10H15N2·C8H7O2·H2O (III); and 4-phenylpiperazin-1-ium trifluoroacetate 0.12 hydrate, C10H15N2·C2F3O2·0.12H2O (IV), have been synthesized. The single-crystal structures of these compounds reveal that all of them crystallize in the triclinic P\overline{1} space group and the crystal packing of (I)–(III) is built up of ribbons formed by a combination of hydrogen bonds of type N—H...O, O—H...O and other weak interactions of type C—H...O and C—H...π, leading to a three-dimensional network. In the crystal of (IV), the cations and the anions are connected by C—H...O, N—H...O and C—H...F hydrogen bonds and by C—H...π interactions, forming sheets which in turn interact to maintain the crystal structure by linking through the oxygen atoms of water molecules and van der Waals interactions, giving the whole structure.

Crystal structures of six 4-(4-nitrophenyl)piperazin-1-ium salts

Six piperazinium salts are reported, five of them are hydrated and two crystallized as 2:2 salts. They exhibit asymmetric units of a common 4-nitro­phenyl­piperazine cation and different p-substituent benzoate anions. Their crystal structures mainly pack as chains stabilized by strong N—H⋯O and O—H⋯O hydrogen bonds and other weak inter­actions such as C—H⋯O and C—H⋯π.

Six piperazinium salts, namely 4-(4-nitro­phenyl)­piperazin-1-ium 4-bromo­ben­zo­ate dihydrate, C₁₀H₁₄N₃O₂⁺·C₇H₄BrO₂⁻·2H₂O, (I), 4-(4-nitro­phenyl)­pi­per­a­zin-1-ium 4-iodo­benzoate dihydrate, C₁₀H₁₄N₃O₂⁺·C₇H₄IO₂⁻·2H₂O, (II), 4-(4-nitro­phenyl)­piperazin-1-ium 4-hy­droxy­benzoate monohydrate, C₁₀H₁₄N₃O₂⁺·C₇H₅O₃⁻·H₂O, (III), 4-(4-nitro­phenyl)­piperazin-1-ium 4-methyl­benzoate monohydrate, C₁₀H₁₄N₃O₂⁺·C₈H₇O₂⁻·H₂O, (IV), 4-(4-nitro­phenyl)­piperazin-1-ium 4-meth­oxy­benzoate hemihydrate, 2C₁₀H₁₄N₃O₂⁺·2C₈H₇O₃⁻·H₂O, (V), and 4-(4-nitro­phenyl)­piperazin-1-ium 4-eth­oxy­benzoate, 2C₁₀H₁₄N₃O₂⁺·2C₉H₉O₃⁻, (VI), have been synthesized and their crystal structures solved by single-crystal X-ray diffraction, revealing that all of them crystallize in the triclinic space group P except for (V), which crystallizes in the monoclinic space group P2₁/c and has a disordered nitro group. Compounds (I) and (II) are isostructural. The crystal packing of (I)–(V) is constructed from organic chains formed by a combination of hydrogen bonds of type N—H⋯O and/or O—H⋯O and other weak inter­actions of type C—H⋯O and/or C—H⋯π, forming sheets, whereas (VI) shows a cationic and anionic-based layer structure.

Crystal structure studies of 4-ethyl-piperazin-1-ium 3,5-di-nitro-benzoate, 4-methyl-piperazin-1-ium 3,5-di-nitro-benzoate and 4-methyl-piperazin-1-ium 4-iodo-benzoate

As part of our ongoing investigation on the chemical and biological properties of piperazinium salts, we synthesized three novel compounds: 1-ethyl-piperazinium 3,5-di-nitro-benzoate (I), 1-methyl-piperazinium 3,5-di-nitro-benzoate (II) and 1-methyl-piperazinium 4-iodo-benzoate (III). The crystal structures of these compounds are built up of organic layers formed by the strong connection between the mol-ecules by hydrogen bonds of type N-H⋯O. These layers are linked through N-H⋯O hydrogen bonds and C-H⋯O inter-actions or C-I⋯N halogen bonding, leading to the formation of a three-dimensional network.

Is lower dose of intramuscular dexamethasone injection beneficial in reducing neonatal respiratory morbidity for elective caesarean section deliveries at 37 to 38 weeks? An observational study

INTRODUCTION

The use of intramuscular (IM) dexamethasone injections before an elective caesarean delivery at term has been shown in multiple randomized controlled trials to reduce the rates of transient tachypnoea of the newborn, and admission to neonatal care. Recent studies have suggested that a complete course of IM steroids can be associated with long term harmful consequences to the infants born, and there have been studies suggesting that a lower dose of IM corticosteroids can be beneficial. Therefore, we aim to establish if halving the dose of dexamethasone to 12mg can demonstrate any benefit for term elective caesarean section deliveries whilst minimizing foetal exposure.

METHODS

An observational controlled study comparing neonatal respiratory morbidities before and after the single dose 12mg dexamethasone was implemented in our obstetrics and gynaecology centre for term elective caesarean section deliveries. We included singleton pregnancies from 37+0 to 38+6 weeks undergoing elective caesarean section into our study. A total of 674 patients fulfilled the inclusion criteria and were recruited. We compared the rates and duration of admission to neonatal intensive care unit, the need for mechanical ventilation and the rate of transient tachypnoea of the newborn in the first half of 2019 without IM dexamethasone injections against the second half of the year when a single dose IM dexamethasone was given.

RESULTS

IM dexamethasone injection did not show any significant benefit with regards to reducing the admission to neonatal care (OR 0.97, p- value 0.69), admission to neonatal intensive care unit (OR 0.91, p- value 0.80), the need for mechanical ventilation (OR 0.98, p- value 0.95), and the incidence of transient tachypnoea of the newborn (OR1.01, p- value 0.96). There was also no significant difference for the duration of admission in the neonatal intensive care unit for both groups (p- value 0.17).

CONCLUSIONS

This study showed that there was no significant benefit gained from the lower dose antenatal corticosteroids for term elective caesarean section deliveries and considering that there have been long term harmful consequences demonstrated from the higher dose of antenatal corticosteroids at term, this practice should therefore be discontinued until a larger study is done to refute these findings. The use of such dexamethasone should only be a viable option in a research setting.

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.

Crystal structures of the recreational drug N-(4-meth-oxy-phen-yl)piperazine (MeOPP) and three of its salts

Crystal structures are reported for N-(4-meth-oxy-phen-yl)piperazine (MeOPP), (I), and for its 3,5-di-nitro-benzoate, 2,4,6-tri-nitro-phenolate (picrate) and 4-amino-benzoate salts, (II)-(IV), the last of which crystallizes as a monohydrate. In MeOPP, C11H16N2O, (I), the 4-meth-oxy-phenyl group is nearly planar and it occupies an equatorial site on the piperazine ring: the mol-ecules are linked into simple C(10) chains by N-H⋯O hydrogen bonds. In each of the salts, i.e., C11H17N2O+·C7H3N2O6 -, (II), C11H17N2O+·C6H2N3O7 -, (III), and C11H17N2O+·C7H6NO2 -·H2O, (IV), the effectively planar 4-meth-oxy-phenyl substituent again occupies an equatorial site on the piperazine ring. In (II), two of the nitro groups are disordered over two sets of atomic sites and the bond distances in the anion indicate considerable delocalization of the negative charge over the C atoms of the ring. The ions in (II) are linked by two N-H⋯O hydrogen bonds to form a cyclic, centrosymmetric four-ion aggregate; those in (III) are linked by a combination of N-H⋯O and C-H⋯π(arene) hydrogen bonds to form sheets; and the components of (IV) are linked by N-H⋯O, O-H⋯O and C-H⋯π(arene) hydrogen bonds to form a three-dimensional framework structure. Comparisons are made with the structures of some related compounds.

Crystal structures of three 6-aryl-2-(4-chloro-benz-yl)-5-[(1H-indol-3-yl)meth-yl]imidazo[2,1-b][1,3,4]thia-diazo-les

Three title compounds, namely, 2-(4-chloro-benz-yl)-5-[(1H-indol-3-yl)meth-yl]-6-phenyl-imidazo[2,1-b][1,3,4]thia-diazole, C26H19ClN4S, (I), 2-(4-chloro-benz-yl)-6-(4-fluoro-phen-yl)-5-[(1H-indol-3-yl)meth-yl]imidazo[2,1-b][1,3,4]thia-diazole, C26H18ClFN4S, (II), and 6-(4-bromo-phen-yl)-2-(4-chloro-benz-yl)-5-[(1H-indol-3-yl)meth-yl]imidazo[2,1-b][1,3,4]thia-diazole, C26H18BrClN4S, (III), have been prepared using a reductive condensation of indole with the corresponding 6-aryl-2-(4-chloro-benz-yl)imidazo[2,1-b][1,3,4]thia-diazole-5-carbaldehydes (aryl = phenyl, 4-fluoro-phenyl or 4-bromo-phen-yl), and their crystal structures have been determined. The asymmetric unit of compound (I) consists of two independent mol-ecules and one of the mol-ecules exhibits disorder of the 4-chloro-benzyl substituent with occupancies 0.6289 (17) and 0.3711 (17). Each type of mol-ecule forms a C(8) chain motif built from N-H⋯N hydrogen bonds, which for the fully ordered mol-ecule is reinforced by C-H⋯π inter-actions. In compound (II), the chloro-benzyl unit is again disordered, with occupancies 0.822 (6) and 0.178 (6), and the mol-ecules form C(8) chains similar to those in (I), reinforced by C-H⋯π inter-actions involving only the major disorder component. The chloro-benzyl unit in compound (III) is also disordered with occupancies of 0.839 (5) and 0.161 (5). The mol-ecules are linked by a combination of one N-H⋯N hydrogen bond and four C-H⋯π inter-actions, forming a three-dimensional framework.

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

Twelve 4-(4-meth-oxy-phen-yl)piperazin-1-ium salts containing organic anions have been prepared and structurally characterized. The monohydrated benzoate, 4-fluoro-benzoate, 4-chloro-benzoate and 4-bromo-benzoate salts, C₁₁H₁₇N₂O⁺·C₇H₅O₂ ^-·H₂O (I), C₁₁H₁₇N₂O⁺·C₇H₄FO₂ ^-·H₂O (II), C₁₁H₁₇N₂O⁺·C₇H₄ClO₂ ^-·H₂O (III), and C₁₁H₁₇N₂O⁺·C₇H₄BrO₂ ^-·H₂O (IV), respectively, are isomorphous and all exhibit disorder in the 4-meth-oxy-phenyl unit: the components are linked by N-H⋯O and O-H⋯O hydrogen bond to form chains of rings. The unsolvated 2-hy-droxy-benzoate, pyridine-3-carboxyl-ate and 2-hy-droxy-3,5-di-nitro-benzoate salts, C₁₁H₁₇N₂O⁺·C₇H₅O₃ ^- (V), C₁₁H₁₇N₂O⁺·C₆H₄NO₂ ^- (VI) and C₁₁H₁₇N₂O⁺·C₇H₃N₂O₇ ^- (VII), respectively, are all fully ordered: the components of (V) are linked by multiple N-H⋯O hydrogen bonds to form a chain of rings; those of (VI) are linked into a three-dimensional framework by a combination of N-H⋯O, C-H⋯O and C-H⋯N hydrogen bonds and those of (VII), where the anion has a structure reminiscent of the picrate anion, are linked into a three-dimensional array by N-H⋯O and C-H⋯O hydrogen bonds. The hydrogensuccinate and hydrogenfumarate salts, C₁₁H₁₇N₂O⁺·C₄H₅O₄ ^- (VIII) and C₁₁H₁₇N₂O⁺·C₄H₃O₃ ^- (IX), respectively, are isomorphous, and both exhibit disorder in the anionic component: N-H⋯O and O-H⋯O hydrogen bonds link the ions into sheets, which are further linked by C-H⋯π(arene) inter-actions. The anion of the hydrogenmaleate salt, C₁₁H₁₇N₂O⁺·C₄H₃O₃ ^- (X), contains a very short and nearly symmetrical O⋯H⋯O hydrogen bond, and N-H⋯O hydrogen bonds link the anions into chains of rings. The ions in the tri-chloro-acetate salt, C₁₁H₁₇N₂O⁺·C₂Cl₃O₂ ^- (XI), are linked into simple chains by N-H⋯O hydrogen bonds. In the hydrated chloranilate salt, 2C₁₁H₁₇N₂O⁺·C₆Cl₂O₄ ^2-·2H₂O (XII), which crystallizes as a non-merohedral twin, the anion lies across a centre of inversion in space group P2₁/n, and a combination of N-H⋯O and O-H⋯O hydrogen bonds generates complex sheets. Comparisons are made with the structures of some related compounds.

Six 1-aroyl-4-(4-meth-oxy-phen-yl)piperazines: similar mol-ecular structures but different patterns of supra-molecular assembly

Six new 1-aroyl-4-(4-meth-oxy-phen-yl)piperazines have been prepared, using coupling reactions between benzoic acids and N-(4-meth-oxy-phen-yl)piperazine. There are no significant hydrogen bonds in the structure of 1-benzoyl-4-(4-meth-oxy-phen-yl)piperazine, C18H20N2O2, (I). The mol-ecules of 1-(2-fluoro-benzo-yl)-4-(4-meth-oxy-phen-yl)piperazine, C18H19FN2O2, (II), are linked by two C-H⋯O hydrogen bonds to form chains of rings, which are linked into sheets by an aromatic π-π stacking inter-action. 1-(2-Chloro-benzo-yl)-4-(4-meth-oxy-phen-yl)piperazine, C18H19ClN2O2, (III), 1-(2-bromo-benzo-yl)-4-(4-meth-oxy-phen-yl)piperazine, C18H19BrN2O2, (IV), and 1-(2-iodo-benzo-yl)-4-(4-meth-oxyphen-yl)piperazine, C18H19IN2O2, (V), are isomorphous, but in (III) the aroyl ring is disordered over two sets of atomic sites having occupancies of 0.942 (2) and 0.058 (2). In each of (III)-(V), a combination of two C-H⋯π(arene) hydrogen bonds links the mol-ecules into sheets. A single O-H⋯O hydrogen bond links the mol-ecules of 1-(2-hy-droxy-benzo-yl)-4-(4-meth-oxy-phen-yl)piperazine, C18H20N2O3, (VI), into simple chains. Comparisons are made with the structures of 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\overline{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.