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).     

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.     

2,4‐Di­nitro­phenyl­hydrazones of 2,4‐di­hydroxy­benz­aldehyde, 2,4‐di­hydroxy­aceto­phenone and 2,4‐di­hydroxy­benzo­phenone

In 2,4‐di­hydroxy­benz­aldehyde 2,4‐di­nitro­phenyl­hydrazone N,N‐di­methyl­form­amide solvate {or 4‐[(2,4‐di­nitro­phenyl)­hydrazono­methyl]­benzene‐1,3‐diol N,N‐di­methyl­form­amide solvate}, C₁₃H₁₀N₄O₆·C₃H₇NO, (X), 2,4‐di­hydroxy­aceto­phenone 2,4‐di­nitro­phenyl­hydrazone N,N‐di­methyl­form­am­ide solvate (or 4‐{1‐[(2,4‐di­nitro­phenyl)hydrazono]ethyl}benzene‐1,3‐diol N,N‐di­methyl­form­amide solvate), C₁₄H₁₂N₄O₆·C₃H₇NO, (XI), and 2,4‐di­hydroxy­benzo­phenone 2,4‐di­nitro­phenyl­hydrazone N,N‐di­methyl­acet­amide solvate (or 4‐­{[(2,4‐di­nitro­phenyl)hydrazono]phenyl­methyl}benzene‐1,3‐diol N,N‐di­methyl­acet­amide solvate), C₁₉H₁₄N₄O₆·C₄H₉NO, (XII), the molecules all lack a center of symmetry, crystallize in centrosymmetric space groups and have been observed to exhibit non‐linear optical activity. In each case, the hydrazone skeleton is fairly planar, facilitated by the presence of two intramolecular hydrogen bonds and some partial N—N double‐bond character. Each molecule is hydrogen bonded to one solvent mol­ecule.     

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).     

6‐(3,4‐Di­fluoro­benzoyl)‐3‐[2‐(4‐pyridyl)­ethyl]‐1,3‐benzo­thia­zol‐2(3H)‐one

A new type of benzo­thia­zolinone derivative with potential pharmacological activity, viz. 6‐(3,4‐di­fluoro­benzoyl)‐3‐[2‐(4‐pyridyl)­ethyl]‐1,3‐benzo­thia­zol‐2(3H)‐one, C₂₁H₁₄F₂N₂O₂S, has been prepared and studied by NMR, IR and single‐crystal X‐ray diffraction techniques. The mol­ecule is not planar, the pyridine and di­fluoro­benzene moieties being located above and below the benzo­thia­zole ring system. The carbonyl O atoms are involved in an intramolecular hydrogen‐bond‐type interaction.     

Three complexes of bis(N‐methyl­benzo­hydro­xamato‐O,O′)copper(II)

The first single‐crystal studies of three bis‐transoid Cu–hydrox­amate salts, bis(3‐methoxy‐4,N‐dimethyl­benzo­hydrox­amato‐O,O′)copper(II), [Cu(C₁₀H₁₂NO₃)₂], bis(4‐chloro‐N‐methyl­benzo­hydro­xamato‐O,O′)copper(II), [Cu­(C₈­H₇­Cl­NO₂)₂], bis(N‐methyl‐3,5‐di­nitro­benzo­hydro­xamato‐O,O′)copper(II)–chloro­form (1/2), [Cu­(C₈­H₆­N₃O₆)₂]·­2CHCl₃, are presented. The Cu atom in each of the title compounds sits at a center of inversion and displays a nearly square‐planar geometry with the hydro­xamate‐O atoms connected to it in a syn configuration. The N atoms are in a transoid configuration. Each five‐membered Cu–hydro­xamate ring is planar, thus providing evidence that a planar N atom is present in each ring. The phenyl groups are twisted with respect to the hydro­xamate group by ～40–54°. The angular strain of the sp² carbonyl oxy­gen is significant (～10° from ideal).     

A neutral complex of an azino–DTDAF compound with TCNQ

In the crystal structure of the title 1:1 complex, ethyl 2‐{[5‐(ethoxy­carbonyl)‐2,3‐dihydro‐3,4‐di­methyl‐1,3‐thia­zol‐2‐yl­idene]­hydrazono}‐2,3‐di­hydro‐3,4‐di­methyl‐1,3‐thia­zole‐5‐carboxyl­ate–7,7,8,8‐tetra­cyano‐p‐quinodi­methane (1/1), C₁₆H₂₂N₄O₄S₂·C₁₂H₄N₄, the planar donor and tetra­cyano‐p‐quinodi­methane (TCNQ) mol­ecules are each located on inversion centres and are stacked alternately. The bond lengths indicate that, in this complex, the donor and acceptor are neutral, as confirmed by IR investigation.     

Di­aqua­bis­(di­methyl sulfoxide)­bis(3,5‐di­nitro­benzoato)­zinc(II) and the synthesis of the Cu,Ni and Co analogs

In order to model processes of chemisorption in organic salts formed between di­nitro­benzoic acids (DNBH) and secondary amines (R₂NH), a series of compounds of composition [M^II(3,5‐DNB)₂(DMSO)₂(H₂O)₂] (where M^II is Zn, Cu, Ni or Co, 3,5‐DNB is the 3,5‐di­nitro­benzoate ion, and DMSO is di­methyl sulfoxide) have been prepared. In di­aqua­bis­(di­methyl sulf­oxide)­bis(3,5‐DNB)­zinc(II), [Zn(C₇H₃N₂O₆)₂(C₂H₆OS)₂(H₂O)₂], the 3,5‐DNB ions and mol­ecules of DMSO are monodentate ligands that are coordinated to the Zn atom through their O atoms. These ligands, together with two mol­ecules of water, form a slightly distorted octahedral coordination environment for the Zn atom, which lies on a center of symmetry.     

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.     

Hydrogen‐bonded one‐dimensional networks in 1:1 complexes of N,N′‐bis(2‐pyridyl)aryldiamines with anilic acid

The 1:1 complexes N,N′‐bis(2‐pyridyl)­benzene‐1,4‐di­amine–anilic acid (2,5‐di­hydroxy‐1,4‐benzo­quinone) (1/1), C₁₆H₁₄N₄·C₆H₄O₄, (I), and N,N′‐bis(2‐pyridyl)­bi­phenyl‐4,4′‐di­amine–anilic acid (1/1), C₂₂H₁₈N₄·C₆H₄O₄, (II), have been prepared and their solid‐state structures investigated. The component mol­ecules of these complexes are connected via conventional N—H?O and O—H?N hydrogen bonds, leading to the formation of an infinite one‐dimensional network generated by the cyclic motif R(9). The anilic acid molecules in both crystal structures lie around inversion centres and the observed bond lengths are typical for the neutral mol­ecule. Nevertheless, the pyridine C—N—C angles [120.9 (2) and 120.13 (17)° for complexes (I) and (II), respectively] point to a partial H‐atom transfer from anilic aicd to the bispyridyl­amine, and hence to H‐atom disorder in the OHN bridge. The bispyridyl­amine mol­ecules of (I) and (II) also lie around inversion centres and exhibit disorder of their central phenyl rings over two positions.     

4‐Methyl‐2‐[N‐(3,4‐methyl­ene­dioxy­benzyl­idene)hydrazino]­thia­zole and its reduction product, 4‐methyl‐2‐[N‐(3,4‐methyl­ene­dioxybenzyl­idene)hydrazono]‐4,5‐di­hydro­thia­zole

The crystal structures of 4‐methyl‐2‐[N‐(3,4‐methyl­ene­dioxybenzyl­idene)hydrazino]­thia­zole, C₁₂H₁₁N₃O₂S, and its reduction product 4‐methyl‐2‐[N‐(3,4‐methyl­ene­dioxybenzyl­idene)hydrazono]‐4,5‐di­hydro­thia­zole, C₁₂H₁₃N₃O₂S, have been determined and compared. In the reduction product, the tautomer observed bears an H atom on the exocyclic N atom. Both compounds form hydrogen‐bonded dimers over centers of inversion.     

Intermolecular interactions and ­molecular geometry in molecular complexes of N,N‐di­methyl­aniline: the 1:1 complex with 1,2,4,5‐tetra­cyano­benzene

The partner mol­ecules of N,N‐di­methyl­aniline–1,2,4,5‐tetra­cyano­benzene (1/1), C₈H₁₁N·C₁₀H₂N₄, are stacked alternately in infinite columns. The N atom of the N,N‐di­methyl­aniline mol­ecule has a partially tetrahedral character and the distance between neighbouring mol­ecules in the stack is relatively short on the side where the lone‐pair electrons of this atom are located. Molecular‐packing analysis of this and three other complexes of N,N‐di­methyl­aniline shows that there is a close relationship between the strength of the intermolecular interaction on this side and the tetrahedral character of the N atom.     

2,3‐Bis(4‐nitro­benzyl­thio)­maleo­nitrile

The maleo­nitrile moiety of the title compound, (2Z)‐2,3‐bis­[(4‐nitro­benzyl)­sulfanyl]­but‐2‐ene­di­nitrile, C₁₈H₁₂N₄O₄S₂, is almost planar. The two benzene rings are nearly parallel to each other and perpendicular to the maleo­nitrile plane. Intermolecular S?S and π–π interactions are observed in the crystal structure.     

1,3‐Benzothia­zole‐6‐carboxamidinium chloride dihydrate

The title compound, C₈H₈N₃S⁺·Cl⁻·2H₂O, has been synthesized and characterized both spectroscopically and structurally. The structure consists of 1,3‐benzothia­zole‐6‐carboxamidinium cations, chloride anions and water mol­ecules, all interconnected by hydrogen bonds into a three‐dimensional network. The 1,3‐benzo­thia­zole moiety is inclined to the 6‐­amidine group by 36.71 (9)°.     

Conformation of N‐methyl‐4‐piperidyl 2,4‐dinitrobenzoate

The crystal structure of N‐methyl‐4‐piperidyl 2,4‐di­nitro­benzoate, C₁₃H₁₅N₃O₆, (I), at 130 (2) K reveals that, in the solid state, the mol­ecule exists in the equatorial conformation, (Ieq). Thus, the through‐bond interaction present in the axial conformation, (Iax), is not strong enough to overcome the syn–diaxial interactions between the axial methyl substituent and the axial H atoms on the two piperidyl ring C atoms either side of the ester‐linked ring C atom. The carboxyl­ate group in (I) is orthogonal to the aromatic ring, in contrast with other 2,4‐di­nitro­benzoates, which are coplanar. The piperidyl–ester C—O bond distance is 1.467 (3) Å, which is actually shorter than other equatorial cyclo­hexyl–ester C—O distances. This shorter piperidyl–ester C—O bond distance is due to the reduced electron demand of the orthogonal ester group.     

Tetrakis(3,5‐di­methyl­pyridine)­dihydrido­silicon dibromide bis(aceto­nitrile) solvate and 3,5‐dimethylpyridinium bromide

In the course of an attempt to synthesize tetrakis(3,5‐di­methyl­pyridine)­dihydridosilicon dibromide, crystals of its aceto­nitrile disolvate, C₂₈H₃₈N₄Si²⁺·2Br^?·2C₂H₃N, (I), and of 3,5‐di­methyl­pyridinium bromide, C₇H₁₀N⁺·Br^?, (II), were obtained in the same reaction flask. They have both been structurally characterized.     

The proton‐transfer compounds of strychnine with achiral salicylic acids: strychninium 3,5‐dinitro­salicylate and the strychninium 5‐nitro­salicylate bis­(5‐nitro­salicylic acid) adduct

In the crystal structures of the proton‐transfer compounds of strychnine with 3,5‐dinitro­salicylic acid, namely strychninium 3,5‐dinitro­salicylate, C₂₁H₂₃N₂O₂⁺·C₇H₃N₂O₇⁻, (I), and 5‐nitro­salicylic acid, namely strychninium–5‐nitro­salicylate–5‐nitro­salicylic acid (1/1/2), C₂₁H₂₃N₂O₂⁺·C₇H₄NO₅⁻·2C₇H₅NO₅, (II), protonation of one of the N atoms of the strychnine mol­ecule occurs and this group is subsequently involved in inter­molecular hydrogen‐bonding inter­actions. In (I), this is four‐centred, the primary being with an adjacent strychninium carbonyl O‐atom acceptor in a side‐to‐side inter­action giving linear chains. Other inter­actions are with the phenolate and nitro O‐atom acceptors of the anionic species, resulting in a one‐dimensional polymer structure. In (II), the N⁺—H inter­action is three‐centred, the hydrogen bonding involving carboxyl O‐atom acceptors of the anion and both acid adduct species, giving unique discrete hetero‐tetramer units. The structure of (II) also features π‐bonding inter­actions between the two acid adduct mol­ecules.     

Hydro­gen‐bonded dimers in N‐(2‐nitro­phenyl­thio)­saccharin

In the title compound, 2‐(2‐nitro­phenyl­thio)‐1,2‐benzo­thia­zol‐3(2H)‐one 1,1‐dioxide, 2‐O₂NC₆H₄S(C₇H₄NO₃S) or C₁₃H₈N₂­O₅S₂, the planes of the saccharin and nitro­phenyl­thiol­ate portions are almost orthogonal. The mol­ecules are linked by C—H?O=S hydrogen bonds [C?O 3.308 (3) Å, H?O 2.44 Å and C—H?O 155°] into cyclic centrosymmetric R²₂(16) dimers, reinforced by aromatic π?π stacking interactions between the nitrated aryl rings.     

A structural hierarchy in the hydrogen‐bonded adduct N,N′‐di­methyl­piperazine–tartaric acid–water (1/2/2): an N‐component N‐dimensional structure (N = 3) with substructures having N = 1 and 2

In the hydrated adduct N,N′‐di­methyl­piperazine‐1,4‐diium bis(3‐carboxy‐2,3‐di­hydroxy­propanoate) dihydrate, [MeNH(CH₂CH₂)₂NHMe]²⁺·2(C₄H₅O₆)^?·2H₂O or C₆H₁₆N₂²⁺·2C₄H₅O₆^?·2H₂O, formed between racemic tartaric acid and N,N′‐di­methyl­piperazine (triclinic P, Z′ = 0.5), the cations lie across centres of inversion. The anions alone form chains, and anions and water mol­ecules together form sheets; the sheets are linked by the cations to form a pillared‐layer framework. The supramolecular architecture thus takes the form of a family of N‐dimensional N‐component structures having N = 1, 2 or 3.     

Three polar derivatives of N‐ethylcarbazole: materials for optical applications

Three N‐ethyl­carbazole derivatives have been synthesized and tested for non‐linear optical (NLO) properties. The compounds are 2‐(9‐ethyl‐9H‐carbazol‐3‐yl­methyl­ene)­malono­nitrile, C₁₈H₁₃N₃, (IIIa), 2‐cyano‐3‐(9‐ethyl‐9H‐carba­zol‐3‐yl)­thio­acryl­amide, C₁₈H₁₅N₃S, (IIIb), and 3‐(9‐ethyl‐9H‐carbazol‐3‐yl)‐2‐(4‐phenyl‐1,3‐thia­zol‐2‐yl)­acrylo­nitrile, C₂₆H₁₉N₃S, (V). It was found that the mol­ecules of (IIIa) and (V) are nearly planar, while non‐planarity is more pronounced for (IIIb). Molecules of (IIIa) and (V) exhibit herring‐bone packing motifs. In (IIIb), the mol­ecules form layers coplanar with (01), within which they form centrosymmetric dimers via N—H?S hydrogen bonds.