共查询到20条相似文献,搜索用时 15 毫秒
1.
《Acta Crystallographica. Section C, Structural Chemistry》2017,73(11):990-993
2,6‐Diaminopyridine (26‐DAP, C5H7N3) is a common intermediate in the synthesis of aromatic azo chromophores, which are widespread in the dyes and pigments industry. Sublimation of commercial 26‐DAP powder yielded a new polymorph, denoted Form II, which grew as colorless orthorhombic needles. Recrystallization from acetone or toluene also yielded Form II as the major phase. Thermal analysis shows that Form II is a less stable polymorph and it converts upon heating at 335 K to the previously reported Form I. 相似文献
2.
Angel Ramos‐Organillo Rosalinda Contreras 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(9):o501-o503
A new sulfate acid polymorph of 1,3‐dihydrobenzotriazole, viz. 1,3‐dihydrobenzotriazolium hydrogensulfate, C6H6N3+·HSO4−, differs from an existing polymorph in that the polymeric interaction between the HSO4− anions, together with different classical (D—H...A) and nonclassical (C—H...A) interactions, changes the space group. 相似文献
3.
Victor Ch. Kravtsov Marina S. Fonari Michael J. Zaworotko Janusz Lipkowski 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(11):o683-o684
A new orthorhombic polymorphic modification of the title compound (alternative name: cis–transoid–cis‐2,5,8,15,18,21‐hexaoxatricyclo[20.4.0.09,14]hexacosane), C20H36O6, has been found and is compared with the previously known monoclinic modification. In the structures of the two polymorphs, the crown‐ether molecules are centrosymmetric and reveal essentially the same molecular shape but different packing motifs. 相似文献
4.
Palladium‐catalyzed coupling reaction of trifluoromethylacetimidoyl iodide with dialkyl vinylphosphonates afforded trifluoromethylated and phosphorylated α, β‐unsatured imines, which gave corresponding quinoline derivatives upon cyclization with Pd/C in nitrobenzene. 相似文献
5.
Jung‐Won Park Jeum‐Jong Kim Ho‐Kyun Kim Young‐Jin Kang Woo Song Lee Yong‐Jin Yoon 《Journal of heterocyclic chemistry》2000,37(6):1603-1606
This paper presents the methoxylation of 4,5‐dichloro‐2‐methyl‐6‐nitropyridazin‐3‐one with potassium carbonate/methanol. 相似文献
6.
Jií Hanusek Pavel Drabina Milo Sedlk Pavel Rosa 《Journal of heterocyclic chemistry》2006,43(5):1281-1285
Acylation of 2‐amino‐N‐methyl‐thiobenzamide with substituted benzoyl chlorides has been used to synthesize the corresponding 2‐benzoylamino‐N‐methylthiobenzamides. Subsequent sodium methoxide‐catalyzed ring closure gives the corresponding 3‐methyl‐2‐phenylquinazoline‐4‐thiones. These compounds were characterized by means of their 1H‐ and 12C‐NMR spectra. The kinetics of the cyclization reaction has been followed with UV‐VIS spectroscopy at 100 °C in methanolic solutions of sodium methoxide. 相似文献
7.
Wojciech Jankowski Maria Gdaniec 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(3):o181-o182
In β‐phenazine, C12H9N2, the molecules show a sandwich herring‐bone type of packing. The experimental crystal structure shows very good agreement with that predicted earlier from systematic searches of potential packing arrangements for the known unit cell [Hammond, Roberts, Smith & Docherty (1999). J. Phys. Chem. B, 103 , 7762–7770]. 相似文献
8.
Dragana Stevanovi Anka Pejovi Sladjana B. Novakovi Goran A. Bogdanovi Vladimir Divjakovi Rastko D. Vukievi 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(2):m37-m40
Recrystallization of the title compound, [Fe(C5H5)(C14H13N2O3)], from a mixture of n‐hexane and dichloromethane gave the new polymorph, denoted (I), which crystallizes in the same space group (P) as the previously reported structure, denoted (II). The Fe—C distances in (I) range from 2.015 (3) to 2.048 (2) Å and the average value of the C—C bond lengths in the two cyclopentadienyl (Cp) rings is 1.403 (13) Å. As indicated by the smallest C—Cg1—Cg2—C torsion angle of 1.4° (Cg1 and Cg2 are the centroids of the two Cp rings), the orientation of the Cp rings in (I) is more eclipsed than in the case of (II), for which the value was 15.3°. Despite the pronounced conformational similarity between (I) and (II), the formation of self‐complementary N—H...O hydrogen‐bonded dimers represents the only structural motif common to the two polymorphs. In the extended structure, molecules of (I) utilize C—H...O hydrogen bonds and, unlike (II), an extensive set of intermolecular C—H...π interactions. Fingerprint plots based on Hirshfeld surfaces are used to compare the packing of the two polymorphs. 相似文献
9.
Rodrigo S. Corrêa Sarita A. Santana Rogrio Salloum Rosalice M. Silva Antnio C. Doriguetto 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(3):o115-o117
A planar conformation of 1,3‐thiazolidine‐2‐thione (TZDTH), C3H5NS2, was crystallized for the first time. The new triclinic polymorph (P) obtained was compared in terms of its intra‐ and intermolecular geometry with three previous reports of a monoclinic polymorph (P21/n). The packing is based on centrosymmetric dimers of TZDTH, linked by N—H⋯S hydrogen bonds. 相似文献
10.
Jana Sopkov‐de Oliveira Santos Alexandre Bouillon Jean‐Charles Lancelot Sylvain Rault 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(8):o582-o584
The crystal structure of the first reported non‐substituted N‐methyldioxazaborocane confirms that the presence of a methyl group attached to the N atom introduces an NB bond length that is longer than that in a simple dioxazaborocane ring. The presence of more N atoms in the vicinity of the B atom in the title compound [systematic name: 6a‐(6‐bromopyridin‐2‐yl)‐3a‐methyl‐2,3,4,5‐tetrahydro‐1,6‐dioxa‐3a‐aza‐6a‐borapentalene], C10H14BBrN2O2, does not modify significantly any structural parameter in the dioxazaborocane ring. On the other hand, a small asymmetry appears in the bond angles of the pyridine C atom next to the B atom. 相似文献
11.
Jan Fbry Michal Duek Pemysl Vank Iegor Rafalovskyi Jií Hlinka Jií Urban 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(12):1153-1160
The structures of 4‐chloro‐3‐nitroaniline, C6H5ClN2O2, (I), and 4‐iodo‐3‐nitroaniline, C6H5IN2O2, (II), are isomorphs and both undergo continuous (second order) phase transitions at 237 and 200 K, respectively. The structures, as well as their phase transitions, have been studied by single‐crystal X‐ray diffraction, Raman spectroscopy and difference scanning calorimetry experiments. Both high‐temperature phases (293 K) show disorder of the nitro substituents, which are inclined towards the benzene‐ring planes at two different orientations. In the low‐temperature phases (120 K), both inclination angles are well maintained, while the disorder is removed. Concomitantly, the b axis doubles with respect to the room‐temperature cell. Each of the low‐temperature phases of (I) and (II) contains two pairs of independent molecules, where the molecules in each pair are related by noncrystallographic inversion centres. The molecules within each pair have the same absolute value of the inclination angle. The Flack parameter of the low‐temperature phases is very close to 0.5, indicating inversion twinning. This can be envisaged as stacking faults in the low‐temperature phases. It seems that competition between the primary amine–nitro N—H...O hydrogen bonds which form three‐centred hydrogen bonds is the reason for the disorder of the nitro groups, as well as for the phase transition in both (I) and (II). The backbones of the structures are formed by N—H...N hydrogen bonding of moderate strength which results in the graph‐set motif C(3). This graph‐set motif forms a zigzag chain parallel to the monoclinic b axis and is maintained in both the high‐ and the low‐temperature structures. The primary amine groups are pyramidal, with similar geometric values in all four determinations. The high‐temperature phase of (II) has been described previously [Garden et al. (2004). Acta Cryst. C 60 , o328–o330]. 相似文献
12.
Agnieszka Czapik Maria Gdaniec 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(4):o198-o201
A new crystalline form of benzene‐1,2‐diamine, C6H8N2, crystallizing in the space group Pbca, has been identified during screening for cocrystals. The crystals are constructed from molecular bilayers parallel to (001) that have the polar amino groups directed to the inside and the aromatic groups, showing a herringbone arrangement, directed to the outside. The known monoclinic form and the new orthorhombic polymorph exhibit two‐dimensional isostructurality as the crystals consist of nearly identical bilayers. In the monoclinic form, neighbouring bilayers are generated by a unit translation along the a axis, whereas in the orthorhombic form they are generated by a c‐glide. Moreover, the new form of benzene‐1,2‐diamine is essentially isomorphous with the only known form of 2‐aminophenol. 相似文献
13.
L. Vijayalakshmi V. Parthasarathi Bharat Varu Narasinh Dodia Anamik Shah 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(9):e401-e402
In the title compound, C23H15NO2, the naphthyl unit is planar and the benzopyran unit is nearly planar. These two moieties are inclined at an angle of 9.10 (6)° with respect to one another. 相似文献
14.
Mihaela Pop Gheorghe Borodi Kees Goubitz Ren Peschar Jan Fraanje Ioan Fenesan Henk Schenk 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(5):o280-o281
The title compound, C11H17N2O3PS2, is a cyclic thiophosphoryl pyrimidine derivative exhibiting insecticidal properties. The crystal structure determination gives evidence for the presence of the thione isomer of the compound. The pyrimidine nucleus is planar and its substituents have small deviations from the least‐squares plane. The dioxaphosphorinane ring adopts a chair conformation. The lack of classical hydrogen bonds and the weak intermolecular interactions lead to a `loose' packing characterized by channels in the structure. 相似文献
15.
Natalia V. Kuratieva Daria Mikhailova Helmut Ehrenberg 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(11):i85-i86
A new polymorph of nonacopper(II) bis(orthoborate) bis(hexaoxodiborate), Cu9(BO3)2(B2O6)2, or Cu3B2O6 with Z′ = 3, has a pseudo‐layered monoclinic structure containing BO3 triangles and B2O6 units consisting of corner‐sharing BO3 triangles and BO4 tetrahedra. The compound was obtained during an investigation of the Li–Cu–B–O system. In contrast to the triclinic form of Cu3B2O6, the layers are linked to one another by BO4 tetrahedra. 相似文献
16.
Farid Naghiyev Ibrahim Mamedov Victor Khrustalev Namiq Shixaliyev Abel Maharramov 《中国化学会会志》2019,66(3):253-256
In this paper, we report a new synthesis route to 4H‐pyran derivatives and a plausible reaction mechanism. The interaction of 5‐acetyl‐2‐amino‐6‐methyl‐4‐phenyl‐4H‐pyran‐3‐carbonitrile with different active methylene reagents gives rise to the cleavage and subsequent recyclization of the pyran ring to afford the corresponding 4H‐pyran derivatives. 相似文献
17.
Viktor Vrbel Jozef Lehotay Drahomír Oktavec tefan Marchalín 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(9):1073-1074
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°). 相似文献
18.
Genivaldo Júlio Perptuo Jan Janczak 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(5):o271-o273
Crystals of the title compound, C4H8N5+·C2F3O2−, are built up of singly protonated 2,4‐diamino‐6‐methyl‐1,3,5‐triazin‐1‐ium cations and trifluoroacetate anions. The CF3 group of the anion is disordered. The oppositely charged ions interact via almost linear N—H...O hydrogen bonds, forming a CF3COO−...C4H8N5+ unit. Two units related by an inversion centre interact through a pair of N—H...N hydrogen bonds, forming planar (CF3COO−...C4H8N5+...C4H8N5+·CF3COO−) aggregates that are linked by a pair of N—H...O hydrogen bonds into chains running along the c axis. 相似文献
19.
George B. Okide 《Journal of heterocyclic chemistry》2001,38(5):1213-1214
The bromine atoms of the title compound were replaced by the requisite amino compound to afford the desired derivatives in high yields. Thus, six target compounds viz‐ bis(diethylamino)‐, bis(dibutylamino)‐, bis(dicyclohexylamino)‐, dipyrrolidino‐, dipiperidino‐, and dipiperazino‐derivatives were obtained and characterized by spectral and elemental analyses. 相似文献
20.
Vladimir N. Nesterov David J. Wiedenfeld Svitlana V. Nesterova Lucas F. Hastings 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(12):o705-o708
The syntheses, X‐ray structural investigations and calculations of the conformational preferences of the carbonyl substituent with respect to the pyran ring have been carried out for the two title compounds, viz. C15H14N2O2, (II), and C20H16N2O2·C2H3N, (III), respectively. In both molecules, the heterocyclic ring adopts a flattened boat conformation. In (II), the carbonyl group and a double bond of the heterocyclic ring are syn, but in (III) they are anti. The carbonyl group forms a short contact with a methyl group H atom in (II). The dihedral angles between the pseudo‐axial phenyl substituent and the flat part of the pyran ring are 92.7 (1) and 93.2 (1)° in (II) and (III), respectively. In the crystal structure of (II), intermolecular N—H⋯N and N—H⋯O hydrogen bonds link the molecules into a sheet along the (103) plane, while in (III), they link the molecules into ribbons along the a axis. 相似文献