3,5‐Di­fluoro‐4‐nitro­pyridine N‐oxide and 3,5‐di­amino‐4‐nitro­pyridine N‐oxide monohydrate

The mol­ecule of 3,5‐di­fluoro‐4‐nitro­pyridine N‐oxide, C₅H₂F₂N₂O₃, is twisted around the C—NO₂ bond by 38.5 (1)°, while the 3,5‐di­amino analogue, 3,5‐di­amino‐4‐nitro­pyridine N‐oxide monohydrate, C₅H₆N₄O₃·H₂O, adopts a planar conformation stabilized by intramolecular hydrogen bonds, with a significant redistribution of π electrons.     

Layered zincoarsenate templated by N,N,N′,N′‐tetra­methyl­ethyl­ene‐di­amine mol­ecules

The title compound, N,N,N′,N′‐tetra­methyl­ethyl­enedi­ammon­ium di­aqua­(arsenate)­(hydrogen arsenate)­dizinc(II), (C₆H₁₈N₂)_0.5[Zn₂(AsO₄)(HAsO₄)(H₂O)₂], is a new zincoarsenate obtained by hydro­thermal synthesis. The structure consists of infinite two‐dimensional anionic layers alternating with planes containing centrosymmetric organic diprotonated template N,N,N′,N′‐tetra­methyl­ethyl­enedi­ammonium cations, [H₃N­C₆H₁₂NH₃]²⁺. The latter are interconnected to the framework through hydrogen bonds.     

Two modifications of l‐alanyl‐l‐tyrosyl‐l‐alanine with different solvent mol­ecules in the crystal lattice

The low‐temperature crystal and mol­ecular structure analyses of two modifications of l ‐alanyl‐l ‐tyrosyl‐l ‐alanine with water, C₁₅H₂₁N₃O₅·2.63H₂O [(I), at 9 K], and ethanol, C₁₅H₂₁N₃O₅·C₂H₅O [(II), at 20 K], solvent mol­ecules in the crystal lattice show that the overall conformations of both modifications of the title tripeptide are practically the same. Moreover, despite the presence of different solvent mol­ecules in the crystal lattice, the specific inter­molecular inter­actions characteristic for individual tripeptide mol­ecules of (I) and (II) are conserved. The crystal packing of the two modifications of Ala‐Tyr‐Ala differ from each other only in the solvent region. The tight arrangements of tripeptide mol­ecules seem to be responsible for similar displacement parameters for all non‐H atoms, despite the different distances from the mol­ecular centre of mass. Comparison of the displacement parameters between the room‐ and low‐temperature structures shows that an average U_eq value decrease of about 80% takes place at 9 K [for (I)] and 20 K [for (II)] with respect to room temperature.     

Charge‐transfer complexes of N‐methyl‐and N‐ethyl­carbazole with 3,5‐di­nitro­benzo­nitrile

In the two title compounds, N‐methyl­carba­zole–3,5‐di­nitro­benzo­nitrile (1/1), C₁₃H₁₁N·C₇H₃N₃O₄, (I), and N‐ethyl­carba­zole–3,5‐di­nitro­benzo­nitrile (1/1), C₁₄H₁₃N·C₇H₃N₃O₄, (II), the donor and acceptor mol­ecules are stacked alternately to form one‐dimensional columns. In (I), the N‐methyl group of the donor is nearly eclipsed with respect to one of the nitro groups of the neighboring acceptor in a column, whereas the N‐ethyl group is anti with respect to the cyano group of the neighboring acceptor in (II).     

The ternary complex 4‐(2‐pyridyl)pyridinium–3,5‐di­nitro­benzoate–3,5‐di­nitro­benzoic acid (1/1/1)

In the title ternary complex, C₁₀H₉N₂⁺·C₇H₃N₂O₆^?·C₇H₄N₂O₆, the pyridinium cation adopts the role of the donor in an intermolecular N—H?O hydrogen‐bonding interaction with the carboxyl­ate group of the 3,5‐di­nitro­benzoate anion. The mol­ecules of the ternary complex form molecular ribbons perpendicular to the b direction, which are stabilized by one N—H?O, one O—H?O and five C—H?O intermolecular hydrogen bonds. The ribbons are further interconnected by three intermolecular C—H?O hydrogen bonds into a three‐dimensional network.     

Charge‐transfer complexes of N‐methyl‐, N‐iso­propyl‐, N‐butyl‐ and N‐iso­butyl­carbazole with 3,5‐di­nitro­benzoic acid

In the title four compounds, C₁₃H₁₁N·C₇H₄N₂O₆, (I), C₁₅H₁₅N·C₇H₄N₂O₆, (II), C₁₆H₁₇N·C₇H₄N₂O₆, (III), and C₁₆H₁₇N·C₇H₄N₂O₆, (IV), the donor and acceptor mol­ecules are stacked alternately to form one‐dimensional columns. In (I), the N‐methyl group of the donor is nearly eclipsed with respect to one of the nitro groups of the neighboring acceptor in a column, whereas the N‐iso­propyl, N‐butyl and N‐iso­butyl groups are in anti positions with respect to one of the nitro groups of the neighboring acceptor in compounds (II)–(IV).     

Diethyl trans‐2,3‐di­benzoyl‐2‐butenedioate

The title compound, C₂₂H₂₀O₆, has a central double bond of length 1.3694 (12) Å. Two benzene rings, lying on different sides of the diethyl 2‐butenedioate main chain, are almost parallel to each other and nearly perpendicular to the main chain. In the unit cell, two symmetry‐equivalent mol­ecules are in general positions and two mol­ecules lie on inversion centres.     

N‐(2‐Carboxy­benzoyl)‐l‐leucine methyl ester

The title compound (with the systematic name 2‐{[(1S)‐1‐(methoxy­carbonyl)‐3‐methyl­butyl]amino­carbonyl}benzoic acid), C₁₅H₁₉NO₅, crystallizes in the monoclinic space group P2₁, with two independent mol­ecules per asymmetric unit. The most notable difference between the two mol­ecules is in the dihedral angles between the planes of the carboxyl group and the benzene ring, which are 3.5 (3) and 25.7 (1)°. This difference may account for the fact that two competing reactions are observed in aqueous solution, namely cyclization to form the imide N‐phthaloyl­leucine and hydrolysis of N‐(2‐carboxy­benzoyl)‐l ‐leucine methyl ester to phthalic acid and leucine.     

A uniform and one‐dimensional stacking of 2,5‐di­chloro­tetra­cyano­quinodimethanide mol­ecules in the tetra­methyl­arsonium salt

In the tetra­methyl­arsonium salt of 2,5‐di­chloro‐7,7,8,8‐tetra­cyano­quinodimethanide [systematic name: tetra­methyl­arson­ium 2,2′‐(2,5‐dichlorocyclohexa‐2,5‐diene‐1,4‐diylidene)bis(propanedinitrile)], C₄H₁₂As⁺·C₁₂H₂Cl₂N₄^? or [As(CH₃)₄](C₁₂H₂Cl₂N₄), the cation lies disordered about a twofold axis and the radical ion lies about an inversion center forming a uniform [interplanar distance 3.35 (2) Å] and one‐dimensional stacking without any slip. The electrical conductivity of the single crystal at room temperature was less than 10^?9 S cm^?1, and the temperature dependence of para­magnetic susceptibility obeyed a one‐dimensional antiferromagnetic Heisenberg model with a spin‐exchange integral of 83 K in the temperature range 1.8–320.0 K.     

Charge‐transfer complexes of 4‐(di­methyl­amino)­pyridine with 2,4‐, 3,4‐ and 3,5‐di­nitro­benzoic acid

In the three title crystal structures 4‐(di­methyl­amino)­pyridinium 2,4‐di­nitro­benzoate, (I), 4‐(di­methyl­amino)­pyri­dinium 3,4‐di­nitro­benzo­ate, (II), and 4‐(di­methyl­amino)pyri­din­ium 3,5‐di­nitro­benzo­ate, (III), all C₇H₁₁N₂⁺·C₇H₃N₂O₆^?, the ions are connected by an N—H?O hydrogen bond. Dihedral angles between the pyridine and phenyl rings are 69.9 (1), 26.7 (1) and 56.2 (1)° in (I), (II) and (III), respectively. Donor–acceptor π–π stacking is observed in (II) and (III), but not in (I).     

2,4,6‐Trimethyl‐N‐nitro­aniline

In 2,4,6‐trimethyl‐N‐nitro­aniline (alternatively called mesitylnitramine), C₉H₁₂N₂O₂, the primary nitramino group is planar with a short N—N bond and is nearly perpendicular to the aromatic ring. The methyl group located in the para position is disordered, each H atom having half‐occupancy. The mol­ecules are linked together along the [100] axis by inter­molecular N—H⋯O hydrogen bonds.     

Three‐in‐one: the novel packing and structures of three independent mol­ecules of a tricyclic boron compound

The three independent mol­ecules in a single crystal of the tricyclic compound 15‐[3‐(dimethyl­amino)prop­oxy]‐5,5,13,13‐tetra­methyl‐1,7,9,14,16‐penta­oxa‐5,13‐diazo­nia‐15‐bora‐6,8‐di­borata­dispiro­[5.1.5.3]hexa­decane, C₁₅H₃₆B₃N₃O₆, are bound in dense layers by C—H⋯O(B) inter­molecular inter­actions. The 3‐(dimethyl­amino)propoxy arms adopt three different conformations with only van der Waals contact distances between the layers. The replicated differences in the B—N bond lengths [mean 1.723 (7) and 1.678 (5) Å] for equivalent geometries are addressed using density functional theory (DFT) calculations.     

N‐(3‐Chloro­phenyl)‐α‐phenyl­nitro­ne: association with benzoic acid through hydrogen bonding

The identity of the title complex, C₁₃H₁₀ClNO·C₇H₆O₂, is confirmed to be a hydrogen‐bonded adduct of benzoic acid and N‐(3‐chloro­phenyl)‐α‐phenyl­nitro­ne. The two aromatic rings in the nitro­ne are trans about the C=N bond.     

Benz­aldehyde 2,4‐di­nitro­phenyl­hydrazone

Crystals of the title compound, C₁₃H₁₀N₄O₄, were obtained from a condensation reaction of benz­aldehyde and 2,4‐di­nitrophenyl­hydrazine. The mol­ecule assumes an approximately planar E configuration. Within the di­nitro­phenyl moiety, the average distance for the aromatic C—C bonds close to the imino group [1.417 (3) Å] is appreciably longer than the average distance for the other aromatic C—C bonds in the same phenyl ring [1.373 (3) Å]. This increased distance may be a result of the overlap of the non‐bonding orbital of the imino N atom with the π orbitals of the arene. It is likely that π–π stacking exists in the crystal structure.     

N,N′‐Di­thio­bisphthal­imide–nitro­benzene (2/1): a Pn solvate with localized solvent mol­ecules ordered head‐to‐tail in channels

N,N′‐Di­thio­bisphthal­imide crystallizes from nitro­benzene solution as a solvate, 2C₁₆H₈N₂O₄S₂·C₆H₅NO₂, having space group Pn. The bisphthal­imide mol­ecules are linked by C—H?O hydrogen bonds and by aromatic π–π‐stacking interactions, forming a framework enclosing continuous channels running along the [100] direction and accounting for ca 20% of the unit‐cell volume. The nitro­benzene mol­ecules lie in these channels, ordered in a head‐to‐tail fashion and linked to the bis­phthal­imide framework by C—H?O and C—H?π(arene) hydrogen bonds.     

Redetermination of 1,3,5‐tri­chloro‐2,4‐di­nitro­benzene

The title compound, C₆HCl₃N₂O₄, is an intermediate in the synthesis of 1,3,5‐tri­chloro‐2,4,6‐tri­nitro­benzene. The crystal structure at 153 K shows no major deviations from the previously reported structure at 295 K other than the expected contraction of the a and c axes and, correspondingly, the β angle.     

Intramolecular hydrogen‐bond‐directed coordination: trans‐bis(N‐benzoyl‐N′‐propyl­thio­urea‐κS)di­iodo­platinum(II) and trans‐bis(N‐benzoyl‐N′‐propyl­thio­urea‐κS)di­bromo­platinum(II)

In the title compounds, trans‐[PtI₂(C₁₁H₁₄N₂OS)₂], (I), and trans‐[PtBr₂(C₁₁H₁₄N₂OS)₂], (II), respectively, intramolecular N—H⋯O (propyl­amine side) hydrogen bonds in the potentially bidentate thio­urea ligands lock the carbonyl O atoms into six‐membered rings, determining the S‐mono­dentate mode of coordination of these ligands. Intramolecular N—H⋯X (X is I or Br) interactions (benzoyl­amine side) lead to slight distortions of the Pt^II coordination spheres from ideal square‐planar geometry. The Pt^II ion is located on an inversion centre in both structures.     

Tri­bromo(3,5‐di­methyl‐2‐nitro­phenyl‐κ2C1,O)­tellurium(IV), bromo(3,5‐di­methyl‐2‐nitro­phenyl‐κ2C1,O)­tellurium(II) and bromo(3,5‐di­methyl‐2‐nitro­so­phenyl‐κ2C1,O)­tellurium(II)

All three title compounds, prepared from bis(3,5‐di­methyl‐2‐nitro­phenyl)­ditellurium, exhibit high degrees of intramol­ecular Te—O coordination. Their Te—O distances increase in the order C₈H₈BrNOTe < C₈H₈BrNO₂Te < C₈H₈Br₃NO₂Te, with distances of 2.165 (3), 2.306 (1) and 2.423 (6) Å, respectively, indicating that C₈H₈BrNOTe may be more aptly described as 1‐bromo‐4,6‐di­methyl‐2,1,3‐benzoxatellurazole.     

3‐Methyl 5‐isopropyl 2‐methoxy­imino­methyl‐6‐methyl‐4‐(3‐nitro­phenyl)‐1,4‐di­hydro­pyridine‐3,5‐di­carboxyl­ate

The crystal structure of the title compound, C₂₀H₂₃N₃O₇, consists of relatively isolated mol­ecules. The substituted 1,4‐di­hydro­pyridine ring adopts a flattened boat conformation. Both ester groups, at positions 3 and 5, have cis,cis geometry. The phenyl ring is nearly planar and is approximately perpendicular to the 1,4‐di­hydro­pyridine ring (dihedral angle 87.70°).     

1:1 Complex of 4‐nitro­benzoic acid and 4‐nitro­pyridine N‐oxide

In the title co‐crystal, C₇H₅NO₄·C₅H₄N₂O₃, the two components are linked by an intermolecular hydrogen bond between the O—H and N—O groups [O?O 2.577 (3) Å]. The interplanar angle between the planes of the rings of the mol­ecules is 5.3 (2)°. The rings are stacked in the crystal with a mean interplanar distance of 3.279 (3) Å.