Crystal and molecular structures of (1,3,4-thiadiazolyl-2)aminodipropionic and (5-methyl-1,3,4-thiadiazolyl-2)aminodipropionic acids

Crystal structures of (1,3,4-thiadiazolyl-2)aminodipropionic (I) and (5-methyl-1,3,4-thiadiazolyl-2) aminodipropionic (II) acids are determined [R = 0.0363 and 0.0529 for 2706 and 1614 reflections with I > 2σ(I) for I and II, respectively]. The similarity and distinctions in the hydrogen-bond systems and molecular-packing motifs of crystals I and II are discussed.     

Synthesis and crystal structures of 5-amino-1-(2-hydroxyethyl)imidazole-4-carboxamide and 5-amino-1-(2-chloroethyl)-4-cyanoimidazole

Both 5-amino-1-(2-hydroxyethyl)imidazole-4-carboxamide (AHIC) and 5-amino-1-(2-chloroethyl)-4-cyanoimidazole (ACCI) have been synthesized and crystallized in the monoclinic space group P2₁/c, Z = 4, with a = 8.420(2), b = 9.759(2), c = 10.583(2) Å, = 111.80(2)° for AHIC and a = 6.139(1), b = 8.522(2), c = 15.156(3) Å, = 96.71(2)° for ACCI. Differences in the molecular geometries of the two compounds are attributed to the differences in the substituents at the 1- and 4-positions of the imidazole ring. The molecular conformation of AHIC is stabilized by intramolecular hydrogen bonding between the 5-amino and the vicinal carboxamide moiety, resulting in an extended planar structural pattern. The presence of the cyano group in the 4-position of ACCI prevents the formation of such an intramolecular hydrogen bond. Both the crystal structures are stabilized by networks of intermolecular hydrogen bonds.     

Crystal and molecular structures of 2-(p-methylbenzyl)- and 2-(p-chlorobenzyl)-5-(p-bromobenzylidene)cyclopentanone. Influence of chloro and methyl substitution on solid-state reactivity

The crystal structures of the title compounds have been determined as part of an investigation into the factors which may influence the solid-state reactivity of benzylidene cyclopentanones. Thep-methyl derivative, which is photoactive in the crystalline state, in monoclinic:P2₁/c,a=18.381(2),b=11.209(2),c=8.285(2) Å,=94.46(12)°, andz=4. The chloro derivative, which is photostable, is also monoclinic:P2₁/c,a=17.522(4),b=7.906(2),c=11.888(2) Å,=91.19(14)°, andz=4. The structures were solved and developed via the heavy-atom method and refined by least-squares to finalR values of 0.062 and 0.061, respectively, using 1902 and 2356 observed reflections measured using an automatic diffractometer. The conformations of the two molecules in their crystal structures are significantly different and lead to dissimilar packing arrangements, which clearly account for the different photochemical behaviors.     

Crystal and molecular structure of (Z)-2-(1,3-benzothiazol-2-yl)-2-(6,7,8,9-tetrahydro-5H-benzocyclohepten-5-ylidene)ethanonitrile

The title compound C₂₀H₁₆N₂S is crystallized in the monoclinic space groupP2₁/c with cell parametersa=10.663(4),b=17.585(9),c=9.418(5)Å,=115.23°(4),V=1598(3)ų,Z=4. The structure was refined by full-matrix least-squares methods using X-ray data set collected at room temperature. A finalR _F =0.033 andR _w =0.048 for 2225 unique reflections withI> 3(I) and 272 variables was obtained. The X-ray crystallographic study establishes theZ stereochemistry of the title compound.     

Crystal and molecular structures of 2′-nitro-4-aminobiphenyl and 2-amino-7-nitrofluorene

2′-nitro-4-aminobiphenyl (5), C₁₂H₁₀N₂O₂, crystallizes in the monoclinic space groupP2₁/c:a = 6.043(2),b =15.795(3),c = 11.577(2) Å, β = 103.42(8) °;D _c = 1.324 g cm^?3 forZ = 4. 2-amino-7-nitrofluorene (3), C₁₃H₁₀N₂O₂, crystallizes in the monoclinic space groupP2₁ n:a = 10.765(2),b = 7.454(4),c = 12.959(2) Å, β = 95.44(1) °;D _c = 1.451 g cm^?3 forZ = 4. Three-dimensional CuKα intensity data were measured with a computer-controlled diffractometer, and the initial phases were obtained by direct methods. The two structures were refined by the full-matrix least-squares method, which gave finalR values for 5 and 3 of 0.045 and 0.043, respectively. Bond lengths in the compounds are normal, apart from slight shortening of the phenyl-phenyl C-C bond and some distortion of the phenyl rings caused by the amino and nitro groups. In 5, the two phenyl rings are twisted by 57.1 °, and the nitro group is twisted by 34.6 ° from the plane of its phenyl group. The carbon backbone of 3 is nearly planar with the two phenyl groups tilted by 4.0 ° to each other. The nitro group in 3 is twisted 5.7 ° from the plane of its phenyl group. There is amino hydrogen to nitro oxygen intermolecular hydrogen bonding in each structure.     

Crystal and molecular structure of 5-amino-1,2,3,4-thiatriazole

The crystal structure of 5-amino-1,2,3,4-thiatriazole has been determined from three-dimensional counter data and refined by full-matrix least-squares techniques. The crystals belong to the monoclinic space groupP2₁/n witha = 3.780(2),b = 10.179(5),c = 10.139(5) Å, = 91.78(4) °, andD _x = 1.74 g cm^–3 forZ = 4. The finalR factor for 572 observed reflections is 0.042. This structure represents the first X-ray structure determination of an ammosubstituted thiatriazole, although electron diffraction and CNDO calculations have been carried out on related systems. The results show that the discrepancy between the observed reactivity and that calculated might be due to the fact that 5-substitution appreciably affects the -system of the heteroaromatic ring.     

Molecular and crystal structures of 2-amino-5-benzoyl-4-(2-nitrophenyl)-3-cyano-4,5-dihydrothiophene

The crystal structure of 2-amino-5-benzoyl-4-(2-nitrophenyl)-3-cyano-4,5-dihydrothiophene is determined by X-ray diffraction analysis. The unit cell parameters are as follows: a = 10.878(2) Å, b = 12.890(3) Å, c = 13.539(4) Å, α = 108.15(2)°, β = 99.26(2)°, γ = 107.13(2)°, V = 1656(2) ų, d _calcd = 1.410 g/cm³, Z = 4, and space group P1ˉ. The molecules occupy two systems of independent positions in the crystal. Similar to the compounds studied earlier in this series, the o-nitrophenyl substituent has a synperiplanar orientation relative to the hydrogen atom at the C(4) atom of the heterocycle. __________ Translated from Kristallografiya, Vol. 45, No. 2, 2000, pp. 282–285. Original Russian Text Copyright ? 2000 by Nesterov, Kuleshova, Samet, Shestopalov.     

Two Novel Potential Anticonvulsant Salts of 5-Amino-2-Sulfonamide-1,3,4-Thiadiazole

Abstract  

Two crystal structures of sulfonamide salts were studied by X-Ray diffraction. The compound C₂H₅N₄O₂S₂ ⁺·H₂O·Cl⁻ (I), (Hats·H₂O·Cl, Hats = protonated 5-amino-2-sulfonamide-1,3,4-thiadiazole) crystallizes in orthorhombic space group, P2₁2₁2₁, with unit cell parameters a = 10.047(4), b = 5.186(2), c = 16.766(6) ? and the compound C₂H₅N₄O₂S₂ ⁺·CH₃O₃S⁻ (II), crystallizes in monoclinic space group, Cc, with unit cell parameters a = 5.378(3), b = 19.707(6), c = 10.014(5) ?, beta = 99.97(1)°. The molecules in compound I are arranged in a helix of alternating water and Hats molecules. Helixes are interconnected by hydrogen bonds provided by Cl⁻ ions and one ring with a graph set R₆⁴ (12) is determined. The crystal structure of compound II presents mesylate and Hats molecules bonded by two hydrogen bond determining a ring with a graph set R₂²(8).     

Crystal and molecular structure of (2-amino-4-methyl-1-pyridinio) cyanoborane

The crystal structure of the title compound, C₇H₁₀N₃B, has been determined by X-ray diffraction using CuK radiation. The crystals are monoclinic,P2₁/c witha=6.941(2),b=15.961(3),c=7.739(2) Å,=90.5(2)° andZ=4. The structure was solved by direct methods, and refined by full matrix least squares to a finalR-value of 056 with 833 observed reflections. The molecule is in the elongated form, but is not planar; the torsion angle C(2)-N(1)-B-C(8) is 82.9(4)°. The bond distances N(1)-B=1.587(5) Å; B-C(8)=1.586(6) Å; C(8)N(3)=1.134(5) Å. The B-C-N moiety is slightly [176.9(4)°] nonlinear. The molecules are linked by weak hydrogen bonds N(2)-H(1N)N(3), N(2)-N(3)=3.055(5) Å and N(2)-H(2N)N(3), N(2)-N(3)=3.165 Å.     

Crystal and molecular structure of 2-(p-tolyl)-2-dehydrosparteine

The formula of the title compound is C₂₂H₃₀N₂,M _T =322.5; monoclinic:P2₁,a=7.569(3),b=9.381(1),c=13.684(4) Å,=105.81(2)°,Z=2,V _c =933.7 ų,D _x =1.15 g cm^–3,(CuK)=5.1 cm^–1. The sparteine skeleton (bis-quinolizidine system) has atrans-trans configuration. RingA has an intermediate form between the sofa and half-chair conformations, ringsB andD-chair, and ringC-boat conformations, respectively. The double bond C(2)=C(3) is equal to 1.343(9) Å. The phenyl ring is planar and makes an angle with a plane through N(1), C(2), C(3), and C(4) atoms equal to 43.9°.     

Crystal and molecular structures of selected oxidative nitration products of aminopyrazine and 2-amino-3-hydroxypyridine

2,3,5,6-Tetraoxopiperazine (I), ammonium 2,3,5,6-tetraoxo-4-nitropyridinate crystal hydrate (II), co-crystallized dimethylammonium 2,3,5,6-tetraoxo-4-nitropyridinate and dimethylammonium chloride (III), and ammonium 2,6-dioxo-3,5-dinitropyridinate (IV) were isolated in the crystalline state and studied by X-ray diffraction. All heterocycles are planar and nonaromatic. They consist of two conjugated moieties linked together by C-C single bonds. The short C...O contacts (2.841–3.048 Å), which link the molecules to form zigzag two-dimensional chains, make a considerable contribution to the formation of the crystal structure of I, whereas hydrogen bonds that form three-dimensional networks play the most important role in the formation of the crystals of II–IV.     

Crystal structures of 2-(2-methoxyphenyl) perimidine and its hemihydrate

The crystal structures of the title compound and that of its hemihydrate have been determined. The anhydrous compound is roughly planar due to an intramolecular hydrogen bond (IMHB). The orange color can be related to its planarity and to the greater degree of overlapping between the perimidine and the phenyl group than in the hemihydrate. The yellow hemihydrate is not planar and the water molecule joins through O-HN hydrogen bonds two molecules related by a crystallographic twofold axis. In solution the compound behaves like the anhydrous form.     

Syntheses,crystal structures and properties of Cd(II) and Ag(I) complexes based on 2-p-methylphenyl-5-(2-pyridyl)-1,3,4-thiadiazole

Abstract

Complexes of [CdL₂(NO₃)₂]·1.5H₂O and [Ag₂(μ-L)₂(NO₃)₂] were synthesized by the reactions of 2-p-methylphenyl-5-(2-pyridyl)-1,3,4-thiadiazole (L) with Cd(NO₃)₂·4H₂O and AgNO₃, respectively. Their structures were determined by single crystal X-ray diffraction. The photophysical property and thermal stability were characterized by FT???IR, UV???Vis absorption, fluorescence, and thermogravimetric analysis (TGA). Both complexes belong to the triclinic system with space group p???1. The central metal of [CdL₂(NO₃)₂]·1.5H₂O has a distorted octahedral geometry [CdN₄O₂], while two central Ag(I) atoms of [Ag₂(μ-L)₂(NO₃)₂] exhibit distorted tetrahedral geometries [AgN₃O].     

Crystal and molecular structure of 2-(1,3-benzothiazol-2-yl)-2-(4-tert-butylcyclohexylidene)ethanonitrile

The crystal and molecular structure of the title compound (C₁₉H₂₂N₂S) has been investigated by single crystal X-ray methods. The crystals are orthorhombic, space groupPbca, with cell dimensions:a=12.082(2)Å,b=11.460(2)Å,c=25.128(4)Å. The structure was solved by direct methods, and refined with 1225 independent reflections by a full-matrix, least-squares procedure, which converged toR=0.042. The benzene and thiazole planes are coplanar and the cyclohexane ring adopts a chair conformation.     

Crystal structures of molecular complexes of 18-crown-6 with 2-aminobenzoic and 5-amino-1-benzyl-1,2,3-triazole-4-carboxylic acid hydrazides

The crystal structures of two host-guest molecular complexes of 18-crown-6 with 2-aminobenzoic acid hydrazide monohydrate (the ratio host: guest: H₂O = 1: 2: 2) (complex I) and 5-amino-1-benzyl-1,2,3-triazole-4-carboxylic acid hydrazide (the host: guest ratio = 1: 2) (complex II) are determined by X-ray diffraction analysis. Crystals I are monoclinic, a = 8.468(2) Å, b = 17.378(3) Å, c = 10.517(2) Å, β = 96.88(3)°, space group P2₁/n, and R = 0.0393 for 6692 reflections. Crystals II are orthorhombic, a = 18.489(1) Å, b = 10.192(3) Å, c = 20.412(2) Å, space group Pbca, and R = 0.0540 for 3513 reflections. In both complexes, the centrosymmetric 18-crown-6 and guest molecules are joined together through the NH?O (crown) hydrogen bonds, which involve all the hydrogen atoms of the hydrazine group. The NH?O=C intramolecular hydrogen bond is observed in the guest molecule. In structure I, the water molecule serves as a bridge between the guest molecules related by the glide-reflection plane and combines the guest-host-guest complexes into layers. In structure II, the guest molecules are linked into chains through hydrogen bonds of the NH?O=C type; in turn, the chains composed of guest molecules and the crown ether molecules bonded to these chains form a layered structure.     

Stereochemistry of diamination of (E)- and (Z)-2-butenes: Crystal and molecular structures of meso- and dl-2,3-diaminobutane ditosylates

Stereospecific anti-addition of diethyl N,N-dibromophosphoramidate (DBPA) to (E)- and (Z)-2-butenes was definitely corroborated by X-ray structural determinations ofthreo- anderythro-2-amino-3-bromobutane hydrochlorides prepared from the corresponding adducts without changing the configuration on either chiral centers. The stereochemistry of azidation ofthreo- anderythro-2-amino-3-bromobutane hydrochlorides leading todl- andmeso-2,3-diaminobutane ditosylates respectively (after reduction of an azide function) was deduced from an X-ray crystallographic analysis of these diamine salts. The X-ray crystallographic analysis was carried out for three compounds: two reaction products and substrate (Scheme 2).     

Crystal and molecular structures of two polymorphs of 4-methyl-2-nitroacetanilide (MNA)

Journal of Chemical Crystallography - The crystal and molecular structure of white (MNA-1) and yellow (MNA-3) forms of 4-methyl-2-nitroacetanilide have been determined by X-ray diffraction...     

Structures of two N-{2-([(5-amino-1,3,4-thiadiazol-2-yl)difluoromethyl]-4-halophenyl}acetamides

Abstract  

The compounds, N-{2-[(5-amino-1,3,4-thiadiazol-2-yl)difluoromethyl]-4-chlorophenyl}acetamide (1: X = Cl) and N-{2([(5-amino-1,3,4-thiadiazol-2-yl)difluoromethyl]-4-bromo-phenyl}acetamide (1: X = Br), are isostructural. The molecules are near ‘‘V’’ shaped with the angles between the two aromatic planes ca. 84° in each case. The various intermolecular interactions, namely N–H···O, N–H···N, N–H···F, and C–H···N hydrogen bonds and C–H···π, C–Cl···π and C–O···π interactions, generate 3-D arrays. Compound (1: X = Cl) crystallizes in the monoclinic space group P21/c with a = 16.9032(7) ?, 10.2193(4) ?, c = 7.5227(4) ?, β = 100.179(3)° and Z = 4. Compound (1: X = Br) crystallizes in the monoclinic space group P21/c with a = 17.2119(4) ?, 10.2167(2) ?, c = 7.5677(2) ?, β = 100.326(2)° and Z = 4.