The Zolmitriptan-Pyridine (1:1) and Zolmitriptan-Propiophenone (3:2) Inclusion Complex

Abstract  

The crystal structures of zolmitriptan with pyridine (I) and propiophenone (II) solvates have been determined by single crystal X-ray diffraction studies. Compound (I) crystallizes in the orthorhombic space group P2₁2₁2₁ with a = 8.5610(5) ?, b = 12.2709(7) ?, c = 19.6201(12) ?, V = 2061.1(2) ?³, and Z = 4, while compound (II) crystallizes in the monoclinic space group P2₁ with a = 15.085(1) ?, b = 19.656(12) ?, c = 21.0860(13) ?, β = 92.068(1)°, V = 6248(4) ?³ and Z = 4. The asymmetric unit of (I), C₁₆H₂₁N₃O₂·C₅H₅N, contains one zolmitriptan molecule and one pyridine solvate, while the asymmetric unit of (II), 3(C₁₆H₂₁N₃O₂)·2(C₉H₁₀O) comprises six zolmitriptan molecules and four propiophenone solvates. In both structures, the N–H···N hydrogen bonds, form an infinite helical chain and generate a C(11)-type motif in (I) and a D₂²(13)-type motif in (II). Both the complexes have layer structures, the layers being constructed from rings (cavity) of four zolmitriptan molecules, hydrogen bonded through N–H···N and N–H···O bonds, where the pyridine (I) and propiophenone (II) solvates are included in an R₄⁴(33) ring.     

The Synthesis and Crystal Determination of 3-Hydroxy-4-(4-methoxyphenyl)-5-(2-nitrophenyl)furan-2(5H)-one

Abstract  

The title compound, C₁₇H₁₃NO₆, was synthesized and structurally characterized by elemental analysis, MS, ¹H NMR and single crystal X-ray diffraction. It crystallizes in monoclinic system space group C 2/c with a = 27.981(6) ?, b = 12.996(3) ?, c = 8.0900(16) ?, β = 91.06(3)°, V = 2941.4(10) ?³, Z = 8, R ₁ = 0.0675, wR ₂ = 0.1626, and T = 298(2) K. The X-ray structure determination revealed that the center furanone ring is nearly coplanar with p-methoxybenzene ring and forms a dihedral angle of 87.2(1)° with the nitrobenzene ring. O–H···O Intermolecular hydrogen bonds link pairs of molecules into centrosymmetric dimers, making a graph set motif of R ₂²(10). The dimers are further assembled into a chain of edge-fused R ₄⁴(34) rings running along the [001] direction. The final three-dimensional supramolecular architecture is stabilized by weak π–π interactions.     

Structure and Antibacterial Activity of 3-(3,4-Dimethoxyphenyl)furan-2(5<Emphasis Type="Italic">H</Emphasis>)-ones

Abstract  

Crystalline hydrate of the title compound (5), C₁₉H₂₆N₂O₅·2(H₂O), was structurally characterized by single crystal X-ray diffraction. It crystallizes in monoclinic system space group P 21/c with a = 7.3987(7) ?, b = 17.8691(16) ?, c = 17.0022(13) ?, β = 112.944(3)°, V = 2070.0(3) ?³, Z = 4, R ₁ = 0.0592, wR ₂ = 0.1016, and T = 298(2) K. The X-ray structure determination revealed that the center furanone ring is nearly coplanar with 3,4-dimethoxybenzene ring, making a dihedral angle of 0.860(69)°. Two kinds of centrosymmetric tetramers characterized by graph-set motifs of R ₇⁸(36) and R ₄⁶(32) are formed through O–H···O, O–H···N and C–H···O hydrogen bonding interactions, which generate a sheet of edge-fused rings parallel to the (011) plane. These sheets are further linked into a three dimensional network by C–H···π interactions. Nine 3-(3,4-dimethoxyphenyl)furan-2(5H)-ones were synthesized and fully characterized by elemental analysis, MS and ¹H NMR. All of them were evaluated for antimicrobial activities against three Gram-positive organisms and a Gram-negative organism, and compound 5 was the most active against Staphylococcus aureus ATCC 25923.     

Crystal Structure of 2-(2,2-Dibromovinyl)-1-methyl-1<Emphasis Type="Italic">H</Emphasis>-imidazole-4,5-dicarbonitrile

Abstract  

The crystal structure of 2-(2,2-dibromovinyl)-1-methyl-1H-imidazole-4,5-dicarbonitrile (C₈H₄Br₂N₄, Mr = 315.92) has been determined by single crystal X-ray diffraction analysis. The compound crystallizes in the monoclinic crystal system with space group P2₁/c and unit cell parameters: a = 15.144(2), b = 16.382(3), c = 8.267(1) ?, β = 95.76(2)^o and Z = 8. The final reliability index is 0.0297 for 2505 observed reflections. The two molecules of 2-(2,2-dibromovinyl)-4,5-dicyano-1-methylimidazole are localized in independent part of unit cell. The crystal packing is stabilized by C–H···N hydrogen bonds and Br···N intermolecular interactions.     

Crystallographic and Conformational Analysis of [(<Emphasis Type="Italic">E</Emphasis>)-2-[(3-Chlorophenylimino)methy])-4-methoxyphenol]

Abstract  The crystal structure of C₁₄H₁₂ClNO₂ was determined by X-ray analysis. It crystallizes in the triclinic space group Pc with a = 12.5346(10) ?, b = 4.5101(3) ?, c = 12.0534(11) ?, α = 90.00o, β = 113.669(6)o, γ = 90.00o, Z = 2, Dx = 1.393 mg/m³, μ (MoK_α) = 0.298 mm⁻¹. The title compound is photochromic and molecule is non-planar. It adopts a phenol–imine tautomeric form with a strong intramolecular O–H···N hydrogen bond and a strong intermolecular C–H···O hydrogen bond. Minimum energy conformations AM1 were calculated as a function of the three torsion angles θ1(C10–C9–N1–C8), θ2(C9–N1–C8–C1) and θ3(N1–C8–C1–C6), varied every 10°. As in the X-ray experiment results, molecule has an angle that makes it non-planar between two aromatic rings in AM1 optimized geometry. Graphical Abstract  Molecular and crystal structure of [(E)-2-[(3-chlorophenylimino)methy])-4-methoxyphenol], C₁₄H₁₂ClNO₂, have been determined by single crystal X-ray diffraction study, and conformational analysis of the title molecule with respect to the selected torsion angle has been achieved by AM1 semi-empirical calculations.      

Synthesis,Crystal Structure and Thermal Properties of <Emphasis Type="Italic">N</Emphasis>-Acetyl-3-(2-furyl)-5-ferrocenyl-2-pyrazoline and <Emphasis Type="Italic">N</Emphasis>-Acetyl-3-(2-thienyl)-5-ferrocenyl-2-pyrazoline

Abstract  

Two novel ferrocenyl substituted N-acetyl-2-pyrazolines, N-acetyl-3-(2-furyl)-5-ferrocenyl-2-pyrazoline (3) and N-acetyl-3-(2-thienyl)-5-ferrocenyl-2-pyrazoline (4), have been synthesized and characterized by FTIR, ¹H-NMR, ¹³C-NMR techniques, elemental analysis and X-ray structure analysis. Thermal properties of these compounds have been determined by TGA, DTA and DSC analysis. Compound 3 (C₁₉H₁₈N₂O₂Fe) crystallizes in the monoclinic space group P21/c and Z = 4, with a = 8.6970(4) ?, b = 18.4725(9) ?, c = 11.0041(5) ?, β = 110.942(3)°. Compound 4 (C₁₉H₁₈N₂OSFe) crystallizes in the orthorhombic space group Fdd2 and Z = 16, with a = 84.242(2) ?, b = 13.5416(5) ?, c = 5.9405(2) ?, β = 90°. In terms of crystal packing, each compound shows different molecular arrangement, which are stabilized by C–H···O intermolecular weak hydrogen bonds, and/or C–H···π interactions.     

Structural Conformation of a Novel 1-Benzhydrylpiperazine Derivative: 1-Benzhydryl-4-(toluene-4-sulfonyl)-piperazine

Abstract  The title compound 1-benzhydryl-4-(toluene-4-sulfonyl)-piperazine was synthesized and the structure was investigated by X-ray crystallography. The title compound, C₂₄H₂₆N₂O₂S crystallizes in the monoclinic crystal class in the space group P2₁/c with cell parameters a = 13.5800(10) ?, b = 8.9630(7) ?, c = 18.9040(10) ?, β = 106.851(3)°, Z = 4 and V = 2202.1(3) ?³. The structure has been solved by direct methods and refined to R ₁ = 0.0468 for 3174 observed reflections I > 2σ(I). The structure reveals that the piperazine ring is in a chair conformation. The geometry around the S atom is a distorted tetrahedron. Graphical Abstract  The title compound 1-benzhydryl-4-(toluene-4-sulfonyl)-piperazine was synthesized and the structure was investigated by X-ray crystallography. The title compound, C₂₄H₂₆N₂O₂S crystallizes in the monoclinic crystal class in the space group P2₁/c with cell parameters a = 13.5800(10) ?, b = 8.9630(7) ?, c = 18.9040(10) ?, β = 106.851(3)°, Z = 4 and V = 2202.1(3) ?³. The structure has been solved by direct methods and refined to R ₁ = 0.0468 for 3174 observed reflections I > 2σ(I). The structure reveals that the piperazine ring is in a chair conformation. The geometry around the S atom is a distorted tetrahedron.

Crystallographic and Conformational Analysis of [(Z)-2-ethoxy-6-[(2-hydroxyphenylamino)methylene]cyclohexa-2,4-dienone]

Abstract  The single crystal X-ray diffraction analysis of the title compound, C₁₅H₁₅NO₃, shows that the structure is adopted to its NH tautomeric form and crystallizes in the orthorhombic space group P bcn with a = 21.2424(15) ?, b = 12.7696(9) ?, c = 9.3605(10) ?, Z = 8, V = 2539.1(4) ?³, D _c  = 1.346 g/cm³. The molecular conformation in the crystal is stabilized by an intramolecular H-bond and the crystal structure is stabilized by the bifurcated O–H···O type intermolecular H-bonds. In order to understand the effects on conformational flexibility of the title molecule, molecular energy profile was calculated as a function of the selected torsion angle by means of AM1 semi-empirical method. Index Abstract  Molecular and crystal structure of [(Z)-2-ethoxy-6-[(2-hydroxyphenylamino)methylene]cyclohexa-2,4-dienone], C₁₅H₁₅NO₃, have been determined by single crystal X-ray diffraction study, and conformational analysis of the title molecule with respect to the selected torsion angle has been achieved by AM1 semi-empirical calculations.      

3-Methyl-3a,4-Dihydro-3H-Thiochromeno[4,3-c]isoxazol

Abstract  The crystal structure of the title compound, C₁₁H₁₁NOS, was determined by an X-ray diffraction analysis. The compound crystallizes in the monoclinic space group P2₁/c with cell parameters a = 10.533(2) ?, b = 12.7826(19) ?, c = 7.6491(17) ?, β = 107.997(17)^°, V = 979.5(3) ?³ and Z = 4. The S containing heterocycle adopts a sofa conformation, whereas the 5-membered ring adopts an envelope conformation. The crystal packing is characterized by weak C–H···N contacts and π-stacking interactions. Graphical Abstract  The title compound, 3-methyl-3a,4-dihydro-3H-thiochromeno[4,3-c]isoxazol was synthesized by an 1,3 dipolar cycloaddition reaction and its crystal structure determined. Single crystal X-ray diffraction analysis reveals that the aromatic 6-membered ring is planar, whereas the ring containing the S atom adopts a sofa conformation and the 5-membered ring an envelope conformation. The methyl group is in an equatorial position.      

Synthesis and Crystal Structure of 2-(2,3,4-Trimethoxy-6-Methylbenzylideneamino)phenol

Abstract  The title compound 2-(2,3,4-trimethoxy-6-methylbenzylideneamino)phenol (C₁₇H₁₉NO₄, M _r = 301.33) was synthesised and characterized by elemental analysis, IR spectra and single crystal X-ray diffraction. The crystal belongs to monoclinic, space group P21/c, with a = 10.4458(14), b = 8.3870(10), c = 17.780(2) ?, β = 91.102(2)^°, V = 1557.4(3) ?³, Z = 4, D _c = 1.285 g/cm³, λ = 0.71073 ?, μ(Mo Kα) = 0.092 mm⁻¹, F(000) = 640. The final refinement gave R = 0.0452, wR(F ²) = 0.1065 for 2,743 observed reflections with I > 2σ(I). X-ray diffraction analysis reveals that the molecule adopts an E configuration at the C=N functional bond. The dihedral angle between the two phenyl rings is 38.3(3)°. The crystal structure is stabilized by C–H···O, O–H···O and O–H···N hydrogen bonds and π–π stacking interactions. Graphical Abstract  The title compound 2-(2,3,4-trimethoxy-6-methylbenzylideneamino)phenol (C₁₇H₁₉NO₄, M _r = 301.33) was synthesised and characterized by elemental analysis, IR spectra and single crystal X-ray diffraction. The crystal belongs to monoclinic, space group P21/c, with a = 10.4458(14), b = 8.387(1), c = 17.780(2) ?, β = 91.102(2)°, V = 1557.4(3) ?³, Z = 4, D _c = 1.285 g/cm³, λ = 0.71073 ?, μ(Mo Kα) = 0.092 mm⁻¹, F(000) = 640. The final refinement gave R = 0.0452, wR(F ²) = 0.1065 for 2,743 observed reflections with I > 2σ(I). X-ray diffraction analysis reveals that the molecule adopts an E configuration at the C=N functional bond. The dihedral angle between the two phenyl rings is 38.3(3)°. The crystal structure is stabilized by C–H···O and O–H···O hydrogen bonds and π–π stacking interactions.      

Synthesis,Structure, and Two Polymorphs of 4-((1,3-Dioxoisoindolin-2-yl)methyl)-1-methoxypyridinium tetrafluoroborate

Abstract  

4-((1,3-Dioxoisoindolin-2-yl)methyl)-1-methoxypyridinium tetrafluoroborate, C₁₅H₁₃BF₄N₂O₃, 1, was obtained by alkylation of the corresponding N-oxide and has been characterized by ¹H and ¹³C NMR, IR, UV spectroscopy and by X-ray crystallography. The crystal undergoes a reversible phase transition between 173 and 293 K. At room temperature, crystals are orthorhombic, space group Pna2₁ with a = 7.2487(3) ?, b = 17.8359 (8) ?, c = 12.4077(6) ?, V = 1604.16(12) ?³, and Z = 4. At 173 K, cations adopt four conformations in monoclinic space group Cc with a = 24.7076(29) ?, b = 14.4145(9) ?, c = 21.8765(25) ?, β = 126.249(17)°, V = 6283.3(7) ?³, and Z = 16. The compound is photostable in the crystal and does not undergo homolytic N–O bond cleavage as observed in solution.     

Crystal Structure and Conformational Analysis of 4-[(<Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-Dimethylamino)Benzylidene]-2-Phenyloxazole-5-One

Abstract  

Molecular and crystal structure of 4-[(p-N,N-dimethylamino)benzylidene]-2-phenyloxazol-5-one, C₁₈H₁₆N₂O₂, have been determined by single crystal X-ray diffraction study. The title compound is monoclinic, with a = 12.1704(23) ?, b = 3.9810(5) ?, c = 30.9603(56) ?, β = 101.176(15)°, Z = 4, D _x = 1.32 g/cm³, μ(Mo Kα) = 0.087 mm⁻¹, and space group is P12₁/c1. The structure was solved by direct methods and refined to a final R = 0.047 for 3166 reflections with I > 2σ(I). The crystal structure is stabilized by C–H⋯O and C–H⋯N type intra-molecular, C–H⋯O type inter-molecular interactions. To enlighten the flexibility and the geometric isomerism (E or Z) of the title compound, the selected torsion angle is varied from −180 to 180° in every 10° separately and molecular energy profile is calculated and analyzed.     

An X-ray Crystallographic Study of 1,4-Di[(<Emphasis Type="Italic">E</Emphasis>)-2-(<Emphasis Type="Italic">p</Emphasis>-tolyl)-1-diazenyl]piperazine

Abstract  

The crystal structure of methyl 1,4-di[(E)-2-(p-tolyl)-1-diazenyl]piperazine (4) has been determined by single crystal X-ray diffraction analysis. The bis-triazene (4) adopts a normal chair conformation in the piperazine ring, with puckering parameters : φ₂ = −29(5)°, Q_T = 0.534(2) ? and θ₂ = 177.0(2)°. The crystal structure of 4 is compared with the structure of the triazene (2a) and the closely related bis-triazenes (3 and 5a). The piperazine ring of 2a and 4 adopt a typical chair conformation, whereas the piperazine ring of 3 adopts an unusual pseudo-boat conformation. Crystal data: 4 C₁₈H₂₂N₆, triclinic, space group P[`1] P\overline{1} , a = 6.8925(2) ?, b = 7.8574(3) ?, c = 16.8856(8) ?, α = 103.103(2)°, β = 90.528(2)°, γ = 101.776(2)° and V = 870.44 (6) ?³, for Z = 2.     

Synthesis, Crystal and Molecular Structure of 1-(2-Chlorobenzyl)-2-methylthio-1H-benzimidazole

Abstract  

1-(2-Chlorobenzyl)-2-methylthio-1H-benzimidazole compound has been synthesized and characterized by elemental analysis, IR and ¹H-NMR spectroscopy and single crystal X-ray diffraction. The compound crystallizes in the triclinic space group P-1 with unit cell parameters a = 17.201 ?, b = 5.873 ?, c = 24.791 ?, α = 67.410(10)°, β = 74.083(11)°, γ = 81.858(12)°. In the crystal packing, no classic hydrogen bonds are founded, but C–H···π interactions are being between the molecules. The molecular geometry and vibrational frequencies of (C₁₅H₁₃ClN₂S) in the ground state have been calculated by using Hartree–Fock (HF) and Density Functional Method (DFT/B3LYP) with 6-31G(d) basis set. The optimized geometric bond lengths and bond angles obtained by using HF and DFT (B3LYP) show the best agreement with the experimental data.     

Synthesis and Structure of Bis(3-dimethylammonium-1-propyne)pentachlorobismuthate(III) (C<Subscript>5</Subscript>H<Subscript>10</Subscript>N)<Subscript>2</Subscript>BiCl<Subscript>5</Subscript>

Abstract  

The synthesis and crystal structure are given for the bis(3-dimethylammonium-1-propyne)pentachlorobismuthate(III) salt. An X-ray investigation has shown that the title compound crystallizes at 298 K in a centrosymmetric monoclinic system, space group C2/c with the following lattice parameters a = 12.6215(4) ?, b = 18.9228(5) ?, c = 8.3134(2) ?, β = 104.100(2)°, V = 1925.70(9) ?³. The structure was solved from 7,716 independent reflections with R ₁ = 0.0457 and wR ₂ = 0.0906, and refined with 85 parameters. The structure consists of disordered 3-dimethylammonium-1-propyne, C₅H₉NH⁺ cations and polynuclear anions in which slightly distorted (BiCl₅)²⁻ anions, sharing an apex are interconnected in chains. These chains are themselves interconnected by means of N–H···Cl originating from the C₅H₉NH⁺ entities, forming a three-dimensional network.     

Synthesis,Characterization, Crystal and Molecular Structure Analysis of 2,6-Dimethyl-3-acetyl-5-carbomethoxy-4-(3-nitrophenyl)-1,4-dihydropyridine

Abstract  A novel unsymmetrical dihydropyridine, possessing carboxymethyl and carbomethoxy groups at C(3) and C(5), respectively, has been produced using a modified Hantzsch synthesis, under solvent free conditions, in a domestic microwave oven. The product obtained was characterized by spectroscopic techniques and finally confirmed by X-ray diffraction studies. The title compound C₁₇H₁₈N₂O₅ crystallizes in the monoclinic system in the space group P2₁/c with cell parameters a = 12.860(2) ?, b = 7.4950(6) ?, c = 16.734(3) ?, β = 94.436(3)°, Z = 4 and V = 1608.1(4) ?³. The 1,4-dihydropyridine ring in the structure is in a flattened boat conformation. The molecule possesses a chiral center at C4. The 3-nitrophenyl ring is nearly orthogonal to the 1,4-dihydropyridine ring. The carbonyl groups at C3 and C5 are oriented in −antiperiplanar and +synperiplanar conformations, respectively. The structure exhibits both inter and intramolecular hydrogen bonds of the type N–H···O and C–H···O. Index Abstract  A novel unsymmetrical dihydropyridine, possessing carboxymethyl and carbomethoxy groups at C(3) and C(5) respectively, has been produced using a modified Hantzsch synthesis, under solvent free conditions, in a domestic microwave oven. The product obtained was characterized by spectroscipic techniques and finally confirmed by X-ray diffraction studies. The title compound C₁₇H₁₈N₂O₅ crystallizes in the monoclinic system in the space group P2_1/c with cell parameters a  =  12.860(2) ?, b  =  7.4950(6) ?, c  =  16.734(3) ?, β = 94.436(3)°, Z = 4 and V = 1608.1(4) ?³. The 1,4-dihydropyridine ring in the structure is in a flattened boat conformation. The molecule possesses a chiral center at C(4). The 3-nitrophenyl ring is nearly orthogonal to the 1,4-dihydropyridine ring. The carbonyl groups at C(3) and C(5) are oriented in −antiperiplanar and +synperiplanar conformations respectively. The structure exhibits both inter and intramolecular hydrogen bonds of the type N–H···O and C–H···O.

Microwave Assisted Synthesis and Crystal Structure of 3,3,6,6-Tetramethyl-9-(phenyl)-1,8-dioxo-2,3,4,5,6,7-hexahydroxanthene

Abstract  The title compound (C₂₃H₂₆O₃, M _r  = 350.44) has been synthesized under microwave irradiation. Its structure was characterized by IR, ¹H NMR spectroscopy and single-crystal X-ray diffraction. The title crystal is in the monoclinic system, space group C with cell dimensions of a = 6.0500(12) ?, b = 19.693(4) ?, c = 16.386(3) ?, β = 97.85(3)o, V = 1,934.0(7) ?³, Z = 4, D _c  = 1.204 g/cm³, λ = 0.71073 ?, μ = 0.08 mm⁻¹, F ₍₀₀₀₎ = 752, the final R = 0.065 and wR = 0.165 for 1,992 observed reflections with I > 2σ(I). In the molecular structure, the pyran ring is of boat conformation, and the two-six-membered rings fused with it adopt envelope conformations. Index Abstract  The title compound (C₂₃H₂₆O₃, M _r  = 350.44) has been synthesized under microwave irradiation. Its structure was characterized by IR, ¹H NMR spectroscopy and single-crystal X-ray diffraction. The title crystal is in the monoclinic system, space group P2₁/C with cell dimensions of a = 6.0500(12) ?, b = 19.693(4) ?, c = 16.386(3) ?, β = 97.85(3)o, V = 1934.0(7) ?³, Z = 4, D _c  = 1.204 g/cm³, λ = 0.71073 ?, μ = 0.08 mm^–1, F ₍₀₀₀₎  = 752, the final R = 0.065 and wR = 0.165 for 1,992 observed reflections with I > 2σ(I). In the molecular structure, the pyran ring is of boat conformation, and the two six-membered rings fused with it adopt envelope conformations.      

Two Crystal Forms of 4-{(2<Emphasis Type="Italic">E</Emphasis>)-2-[1-(4-Methoxyphenyl)ethylidene] hydrazinyl}-8-(trifluoromethyl)quinoline

Abstract  

The Schiff base, 4-{(2E)-2-[1-(4-methoxyphenyl)ethylidene] hydrazinyl}-8-(trifluoromethyl)quinoline, crystallizes in two polymorphic forms depending on the solvent. One of these forms is monoclinic (1M), space group P2₁/c with a = 10.2906(10) ?, b = 8.9211(7) ?, c = 18.4838(15), β = 97.271(8)°, and the other is orthorhombic (1O), space group Pbca, unit-cell parameters: a = 13.6485(12) ?, b = 9.0588(9) ?, c = 27.400(2) ?. The molecules in either crystalline form have similar bond lengths and angles, but one is nearly planar while the other has a significant twist. In monoclinic form the dihedral angle between terminal ring planes is 17.26(8)° while in the orthorhombic one it is 26.11(5)°, and in this latter case the central chain is almost coplanar with the quinoline ring system while in the former these two planes are significantly twisted. The crystal structures of both forms are determined by the interplay of van der Waals forces and weak directional interactions C–H···F, π···π stacking, and—in the case of 1M—short intermolecular C–F···N contact. The crystals of 1M decomposes slowly into the powder while the other form is stable. The powder diffraction pattern of the product of decomposition of 1M is similar to that calculated for 1O. This suggests that the decomposition is a consequence of the phase transition of the less stable monoclinic into more stable orthorhombic form.     

Crystal and Molecular Structures of Two Triazole Derivatives: 4-Cyclopropyl-4,5-dihydro-1H-1,2,3-triazole and Methyl 1-benzyl-1H-1,2,3-triazole-4-carboxylate

Abstract  

The molecule in 4-cyclopropyl-4,5-dihydro-1H-1,2,3-triazole (I) is disposed about a mirror plane with the triazole ring lying in the plane and being orthogonal to the cyclopropyl ring. Considerable delocalization of π-electron density within the triazole ring is indicated by the pattern of bond distances in (I). The molecule of methyl 1-benzyl-1H-1,2,3-triazole-4-carboxylate (II) adopts a curved shape with the dihedral angle formed between the triazole and benzene rings being 63.23(8)°. By contrast to (I), localization of π-electron density within the triazole ring in (II) is indicated. Both (I), via N–H···N hydrogen bonding, and (II), via C–H···O and C–H···N interactions, associate in the solid state to form supramolecular chains. In (I), the chain is a zigzag with a flat topology, whereas in (II) the linear chain has a curved topology. Compound (I) crystallizes in the orthorhombic space group Pnma with a = 5.6470(2) ?, b = 7.3359(4) ?, c = 13.4404(7) ?, and Z = 4. Compound (II) crystallizes in the monoclinic space group P2₁/c with a = 12.1314(5) ?, b = 5.5951(2) ?, c = 16.4339(7) ?, β = 111.269(2)°, and Z = 4.     

Crystal Structures of 1,7-Bis(furyl)-4-(1,3-dithiolan-2-ylidene)-1,6-heptadiene-3,5-dione and 1,7-bis(thienyl)-4-(1,3-dithiolan-2-ylidene)-1,6-heptadiene-3,5-dione

Abstract  

The title compounds (bis(alkenoyl) ketene dithioacetals) were prepared starting from the cyclic acyl ketene dithioacetal and aromatic aldehydes. These compounds were characterized by IR, ¹H NMR, mass spectral studies and X-ray crystal structure analysis. The bis(furyl) ketene dithioacetal crystallized in the space group P[`\text1] P{\bar{\text{1}}} with unit cell dimensions a = 7.7626(12) ?, b = 9.0217(13) ?, c = 26.827(5) ?, α = 86.271(14)°, β = 87.643(14)°, γ = 66.286(11)° and the structure was refined to an R-factor of 0.0528 while bis(thienyl) ketene dithioacetal crystallized in the space group P2₁/c with unit cell dimensions a = 10.2433(9) ?, b = 10.4142(6) ?, c = 18.0973(18) ?, β = 106.0° and the structure was refined to an R-factor of 0.0446. The ketenedithioacetal functionality present between the carbonyl groups prevents the possibility of keto-enol tautomerization in these compounds. In both the crystal structures, the crystal packing is stabilized by C–H···O hydrogen bonds as well as van der Waals interactions.