Evidence for hydrogen bonds in 1,2-dimethyl-3-propylimidazolium chloride and its chloroaluminate molten salts

The crystal structure of l,2-dimethyl-3-propylimidazoIium chloride (DMPICl) reveals the formation of hydrogen bonds between the ring, methyl, and methylene hydrogens and the chloride ion. Although the aromatic rings are found in stacks, aromatic-aromatic interactions are precluded by the 6.98 Å distance between the rings. From IR and¹HNMR spectroscopies, it is determined that only the hydrogen bonds between the ring hydrogens and the chloride ion persist in the room-temperature molten salts obtained from combining DMPIC1 with AlCl₃.     

The role of hydrogen bonding in pseudo-macrocyclic ring formation in 2,6-dimethyl-1,3,5,7-cyclooctatetraene 1,3,5,7-tetracarboxylic acid monohydrate

2,6-Dimethyl-1,3,5,7-cyclooctatetraene-1,3,5,7-tetracarboxylic acid 3, C₁₄H₁₄O₉, was prepared by thermolysis of the corresponding semibullvalene and characterized by spectroscopic and single-crystal X-ray diffraction studies. The monohydrate of 3 crystallizes in the tetrahedral space group P-4n2, a = 11.0924(3) Å, c = 12.6799(5) Å, V = 1560.15(9) ų, Z = 4. The cyclooctatetraene ring adopts a tub-shaped conformation with a crystallograpically imposed twofold rotational symmetry, and is composed of localized C=C double bonds in the 1,3,5, and 7 positions with an average interatomic distance of 1.327 (5) Å and C–C single bonds with an average interatomic distance of 1.489(5) Å. The average C=C–C angle in the ring is 122.6(3)°. Each symmetry generated eight-membered ring contains four carboxyl groups, two of which are coplanar with the methyl groups across the C=C ring atoms. However, across the C–C bonds the carboxyl groups and the methyl groups show a torsion angle of 64.3(4)°. The presence of a water molecule in the crystal lattice generates a three-dimensional network of close hydrogen bondings between water and the carboxyl groups of multiple rings. This creates a network of orthogonal 10-membered rings between the 8-membered rings. Two given cyclooctatetraene rings are intermolecularly hydrogen bonded not only directly through their carboxyl groups but also via a bridging water molecule. This effect is rare in polycarboxylic acids and their monohydrates which bond only with water or among themselves.     

Synthesis and X-ray structure analysis of benzoic acid [1-(6-methyl-2,4-dioxo-3,4-dihydro-2H-pyran-3-yl)eth-(E)-ylidene]-hydrazide with a water molecule (C15H14N2O4?H2O)

The crystal structure of the title compound has been determined by X-ray diffraction methods. It crystallizes in the monoclinic space group P2₁/n with cell parameters a = 7.097(1) Å, b = 19.257(1) Å, c = 10.893(1) Å, = 106.17(2), V = 1429.8(3) ų and Z = 4. The final reliability index is 0.059 for 2419 observed reflections. The molecule comprises of two six- membered rings which are abridged together through a network of C–N, N–N and C–N bonds. There are three keto functional groups and two methyl groups at various locations of the molecule. The C9 atom of methyl group and O2 of the keto group are deviated significantly from the mean plane of the molecule. Both the six-membered rings are planar and it is evident from the magnitude of their exocyclic torsion angles. The molecular structure is stabilized by few intra and intermolecular hydrogen bonds.     

Synthesis,structure and IR characterization of disodium tetra(9,10-dihydro-9-oxo-10-acridineacetato)zincate(II) bis(ethanol) heptahydrate

The synthesis, crystal structure and IR data are reported for Na₂[Zn(CMA)₄]·2EtOH·7H₂O, where CMA^– is the 9,10-dihydro-9-oxo-10-acridinacetate ion. The complex crystallizes in the monoclinic space group P2/n, with cell dimensionsa=17.335(9),b=8.440(5),c=21.875(12) Å, =91.94(5)°,Z=2. The structure was solved by direct methods and refined to a finalR value of 0.0363 for 3022 non-zero reflections. The Zn²⁺ ion occupies twofold axis and is coordinated to four carboxylate ligands, the ZnO₄ tetrahedron is considerably distorted with Zn–O distances of 1.978(3) and 1.961(3)Å. Each Na⁺ cation interacts with two water, one ethanol, and three carboxylate O atoms comprising distorted octahedron. The Zn²⁺ and Na⁺ cations are linked through monooxygen and syn-syn carboxylate bridges forming a trinuclear, mixed-metal cluster. The Zn...Na separation is 3.267(2)Å and Na...Na distance equals 3.520(2)Å. All oxygen bonded H-atoms are utilized in hydrogen bonds. The acridone rings overlap in the crystal with the 3.5 Å interlayer separations. The compound has been characterized by IR spectroscopy.     

Structure and characterization of bis(N-p-chloro-phenyl-salicylideneaminate) Schiff base copper(II) complex: Cu[N-p-Cl-Ph-Sal]2

The crystal and molecular structure of the title compound has been determined by X-ray crystallography. It crystallizes in the monoclinic system, space group P2₁/c, with lattice parameters a = 13.678(3), b = 10.729(2), c = 8.1996(2) Å, = 98.96°, V = 1188.7(4) ų, and Z = 4. The crystal structure contains two centrosymmetric molecules of bis (N-p-chloro-phenyl-salicylideneaminate) Schiff base copper(II). Copper(II) ion is coordinated in a slightly distorted trans square-planar configuration, the distortion consisting of a reduction of the N–Cu–O angle with the chelate rings from the ideal value of 90°. The p-chlorophenyl rings with salicylidene moieties form a dihedral angle of 38.96°.     

Crystal and molecular structure of trans-(tricarbonyl)bis(trans-2,2,3,4,4-pentamethyl-1-phenylphosphetane)iron

The title compound crystallizes in the monoclinic space groupP2₁/a witha=13.092(2) Å,b=15.853(2) Å,c=15.406(3) Å,=103.00(1)°,V=3116(1) ų, andD _calc=1.237 g cm^–3 forZ=4. The structure was solved by direct methods, and refined to a finalR value of 0.057. The phosphetane ligands adopt a nonlinear trans relationship. The four-membered rings are non-planar and have different flap angles of 6.1 and 20.3°. Virtual coupling is evident in the¹³C NMR spectrum of the title compound. Comparison of the¹³C NMR spectral data of this molecule with the parent phosphine ligand, the ligand oxide, and the mono-phosphine iron complex is provided.     

Carnosol. Crystal structure,absolute configuration,and spectroscopic properties of a diterpene

The structure and absolute configuration of naturally occurring Carnosol have been investigated by X-ray analyses. Crystal data are: orthorhombic P2₁2₁2;a=15.762(1),b=13.755(1),c=7.7747(7) Å,Z=4,V=1688.2 ų, andR=0.031 (2569 reflections). The absolute configuration is established at a significance level better than 0.995 according to HamiltonsR-factor test and is in accordance with that predicted experimentally by chemically means. Correlation of the solid-state IR pattern of the regions sensitive to hydrogen bonding (CO and OH stretching bands) with the X-ray crystal structure is excellent and shows, that even weak inter- and intramolecular hydrogen bonds may be unambiguously identified by IR spectroscopy. The variable-temperature nuclear magnetic resonance studies (NMR) show that the twinning of the signals from the isopropyl methyl protons cannot be due to hindered rotation but can be ascribed magnetic nonequivalence induced by the chiral centers.     

Crystal structure, thermal analysis, and IR spectrometric investigation of bis(tert-butylammonium) sulfate

Chemical preparation, X-ray single crystal, thermal analysis, and IR spectrometric investigation of (C₄H₁₂N)₂SO₄, denoted tBAS, are described. The compound crystallizes in the monoclinic system with C2/c space group. Its unit cell dimensions are a = 11.1585(5) Å, b = 6.2148(4) Å, c = 20.070(1) Å, = 102.004(4)°, V = 1361.4(1) ų, and Z = 4. The crystal structure of tBAS can be described as a typical thick layered organization built by all the components of the structure and centered by planes z = 1/4 and 3/4. Connection in these layers are established by N—H···O hydrogen bonds. Thermal analysis shows a reversible weak phase transition.     

The molecular structure of acetato[2-(pyridin-2′-yl)phenyl]mercury(II)

The crystal structure of the title compound was determined by X-ray crystallography. The compound crystallizes in the monoclinic crystal system witha=8.152(4),b=17.994(7),c=8.634(9) Å, =108.92(5)°, space group P2₁/c (N:14),V=1198.02 ų,Z=4. The mercuryl(II) atom forms two strong, almost colinear bonds (bond angle 176.1(4)°) with a carbon of the phenyl ring (Hg–C=1.99(1) Å) and one of the acetate oxygen atoms (Hg–O(1)=2.005(7) Å). These primary bonds are supplemented by secondary intramolecular interactions with the pyridine nitrogen (Hg...N=2.727(9) Å) and the other acetate oxygen (Hg...O(2)=2.925(8) Å), although the latter is very weak and the acetate anion therefore practically monodentate. Weak additional intermolecular Hg–C and Hg–O(1)interactions contribute to the lattice structure.     

4-Hydroxy-N′-[(1E)-1-(4-methylphenyl)ethylidene]benzohydrazide: Synthesis, crystal structure, and spectroscopic studies

The titled compound has been synthesized by reaction of 4′-methylacetophenon with 4-hydrox-ybenzohydrazide in presence of catalytic amount of glacial acetic acid. The compound is characterized by elemental analysis, IR, ¹H NMR, ¹³C NMR and UV-visible spectra. The crystal structure was determined by X-ray diffraction method. Both X-ray data and NMR spectra indicate that the molecule exists in a trans configuration with respect to the C=N bond. The observation of strong ν(C=O) peak in IR spectra of the aroylhydrazone compound suggests that it is in keto form in solid state. X-ray diffraction results confirm this suggestion. In the crystal structure, there are N-H...O and O-H...O hydrogen bonds and weak C-H...π interaction.     

Crystal structure of benzimidazolium dichromate

The X-ray crystal structure of benzimidazolium dichromate is determined. The compound C₁₄H₁₄Cr₂N₄O₇ is Triclinic in P-1 with a = 8.2722(8) Å, b = 10.0269(10) Å, c = 11.7001(11) Å, = 102.073(2)°, =100.483(2)°, = 67.288(2)°, V = 869.88(15) ų, D _calc = 1.734 g/cm³, and Z = 2. A dichromate ion connects two benzimidazolium rings via hydrgen bonds, as leads to face-to-face intramolecular aromatic stacking. The major force of crystal formation comes from hydrogen bonds, and an intermolecular hydrogen bridge is formed to connect two neighbored dichromate ions.     

Synthesis,spectroscopic and X-ray structural study of 4-p-methoxy-phenylimino-3-hydroxyimino-2-pentanone

4-p-Methoxy-phenylimino-3-hydroxyimino-2-pentanone has been synthesized, characterized by elemental analysis. IR, NMR and mass spectroscopies and its structure determined by single crystal X-ray diffraction. It crystallizes in the orthorhombic space group P2₁2₁2₁, witha=7.2294(7),b=11.540(1),c=14.670(2) Å. Spectroscopic and X-ray data clearly indicate that the oxime tautomer is present. In the solid state, the geometrical isomer is the EZ, which is also the main species in solution according to NMR data. The two C=N bonds are not conjugated to each other.     

Structure of exo,exo-2,3-endo,endo-5,6-tetrabromobicycloheptane

The X-ray crystal structure analysis of the title compound, exo,exo-2,3-endo,endo-5,6-tetrabromobicycloheptane, C₇H₈Br₄, which is a product of high temperature bromination of norbornadiene, shows that the skeleton of the molecule is not changed after two bromine molecules are added via successive bromination reactions. The addition of Br₂ to both double bonds occurs (contrary to our expectation) in a syn fashion. It crystallizes in the orthorhombic space group Pbca with a = 15.688(2), b = 13.345(2), c = 9.461(1) Å, V = 1980.7(3) ų, Z = 8 and Dx = 2.762 gcm^–3.     

Crystal structure and spectroscopic study of 6a,7a,13b,13c-tetrahydro-6a-hydroxy-2,3,11,12-tetramethoxy-6,6,8,8-tetramethyl-6H,8H-bischromeno-[3,4-b:4′,3′-d]furan,a dimer of precocene II 3,4-epoxide

The X-ray crystal structure of the title compound has been determined. The crystals are orthorhombic:Pcab, a=9.857(5),b=15.274(5),c=32.601(14) Å,V _c =4908.4 ų;Z=8;D _x =1.279 Mg m^–3; (MoK)=0.71069 Å;=0.88 cm^–1,F(000)=2016, temperature of measurement 294 K. The structure was solved by direct methods, and refined with 932 reflections to a finalR value of 0.071. The two six-membered rings show distorted boat conformations and the tetrahydrofuran ring exhibits a half-chair conformation. Mass spectra, IR spectrum, and¹H and¹³C NMR spectra are also reported.     

Synthesis,Crystal Structure and Antibacterial Activity of 5-Bromonicotinic Acid [1-(4-Chlorophenyl)methylidene]hydrazide Monohydrate Methanol Solvate

Abstract  The compound 5-bromonicotinic acid [1-(4-chlorophenyl)methylidene]hydrazide monohydrate methanol solvate, derived from the condensation reaction of 5-bromonicotinic acid hydrazide with 4-chlorobenzaldehyde in a methanol solution, was synthesized and characterized by elemental analysis, IR spectrum, ¹H NMR and X-ray single crystal determination. The compound crystallizes in the triclinic space group P − 1 with unit cell dimensions a = 6.9360(14) ?, b = 10.070(2) ?, c = 12.267(3) ?, α = 84.39(3)°, β = 86.10(3)°, γ = 80.50(3)°, V = 839.8(3) Ǻ³, Z = 2, R ₁ = 0.0724, and wR ₂ = 0.1720. X-ray structure determination reveals that the compound has a trans configuration with respect to the C=N double bond or C–N single bond. In the crystal structure, molecules are linked through intermolecular O–H···N, O–H···O, and C–H···O hydrogen bonds, forming layers parallel to the ab plane. The preliminary biological tests show that the compound has excellent antibacterial activity. Index Abstract  The compound 5-bromonicotinic acid [1-(4-chlorophenyl)methylidene]hydrazide monohydrate methanol solvate, derived from the condensation reaction of 5-bromonicotinic acid hydrazide with 4-chlorobenzaldehyde in a methanol solution, was synthesized and characterized by elemental analysis, IR spectrum, ¹H NMR and X-ray single crystal determination. The molecule of the compound has a trans configuration with respect to the C=N double bond or C–N single bond. In the crystal structure, molecules are linked through intermolecular O–H···N, O–H···O, and C–H···O hydrogen bonds, forming layers parallel to the ab plane. The preliminary biological tests show that the compound has excellent antibacterial activity.      

Synthesis and crystal structure of 3,4-trans-4, 5-trans-2-amino-3-cyano-1,3-dimethyloxycarbonyl-4, 5-di(3,4-methyl-enedioxylphenyl) cyclopentene

The 3,4-trans-4,5-trans-2-amino-3-cyano-1,3-dimethyloxycarbonyl-4,5-di-(3,4-methyl-enedioxylphenyl) cyclopentene has been synthesized and characterized by IR, ¹H NMR, Elemental analysis, and X-ray crystallography. It crystallizes in the monoclinic space group P2₁/n, with a = 10.936(3) Å, b = 10.142(3) Å, c = 20.001(4) Å, = 93.81(2)°, and D _calc = 1.390 g cm^–3 for Z = 4. X-ray analysis reveals that the phenyl groups and the alkoxyl carbonyl group are in the equatorial positions. The dihedral angles between the phenyl groups and the central five-membered ring are 73.08° and 62.15°. In addition, there are intermolecular hydrogen bonds in the crystal lattices.     

Methyl 4-((E)-2-{3-[(3-{ (E)-2-[4-(methoxycarbonyl)phenyl]- 1-diazenyl}-5,5-dimethylhexahydro-1-pyrimidinyl)methyl]-5,5-dimethylhexahydro-1-pyrimidinyl-1-diazenyl) benzoate. X-ray crystal structure

Methyl 4-((E)-2-{3-[(3-{(E)-2-[4-(methoxycarbonyl)phenyl]-1-diazenyl}-5, 5-dimethyl hexahydro-1-pyrimidinyl)methyl]-5, 5- dimethylhexahydro-1- pyrimidinyl}-1- diazenyl) benzoate (1) has been synthesized by reaction of a mixture of formaldehyde and 2,2-dimethyl-1,3-propanediamine with p-methoxycarbonylbenzenediazonium chloride. The crystal structure of 1 has been determined by single crystal X-ray diffraction analysis. The crystals of 1 displayed problems of disorder; the asymmetric unit is built up by two independent molecules, which display disorder within a methoxycarbonyl group. The two independent molecules in the asymmetric unit are very similar, differing only slightly about the mutual orientation of the aryltriazenyl groups. With respect to the N–C–N bridge between the hexahydropyrimidinyl rings, the two equivalent fragments containing the triazene moieties are in a cis orientation. The N–N single bonds, in the range 1.319(4)–1.348(4) Å, and the N=N double bonds, in the range 1.255(5)–1.275(4) Å, indicate significant conjugations within the triazene moieties. All the hexahydropyrimidine six-membered rings adopt a chair conformation as shown by their puckering parameters. The crystal packing is determined only by simple van der Waals interactions. The crystal structure of 1 is compared with the previously reported structure of the unbranched hexahydropyrimidine analogue 2. Crystal data: 1 C29H40N8O4, triclinic, space group P-1, a = 13.9652(2), b = 14.2908(3), c = 16.6129(4) Å, = 97.279(1), = 90.872(1), = 107.385(1), V = 3133.6(1) ų, for Z = 4.     

Solution and solid-state hydrogen bond patterns ofo-methoxy- ando-ethoxybenzoic acids

The hydrogen bond patterns ofo-alkoxybenzoic acids have been shown previously to involve intramolecular hydrogen bonds. In this paper we show thato-methoxybenzoic acid (I) and o-ethoxybenzoic acid (II) both exist as monomers with intramolecular hydrogen bonds in solution but that, in the solid-state,I crystallizes as hydrogen-bonded dimers whileII crystallizes with an intramolecular hydrogen bond. The correlation between solution and solid-state hydrogen bond patterns is made using solution and solid-state IR and NMR methods and by correlating the solid-state patterns with known X-ray crystal structures. The crystal structure ofI is reported here. Crystal data: monoclinicP2₁/n;a=7.002(2),b=14.945(9),c=7.719(4) Å,=115.44(3)°,Z=4,V=729.4 ų, andR=0.046 (1660 reflections).     

Molecular and crystal structure of 2-amino-6-dimethylamino-4-(tricyclo[3.3.1.13, 7]dec-1-yl) methyl-1,3,5-triazine

The crystal and molecular structure of the title compound has been determined by X-ray crystallographic studies. The compound crystallizes in the triclinic space groupP¯1 witha=10.777(8) Å,b=13.003(9) Å,c=13.045(8) Å, =72.26°(4),=104.25°(5), =108.87°(5) andZ=4. The structure was solved by direct methods and full-matrix least-squares refinement converged to a finalR=0.083 for 2656 observed reflections. The two independent molecules differ only in orientation of the adamantyl moiety. Both of them utilize the two hydrogens of the amine nitrogen N(7) to make hydrogen bonds linking the molecules into infinite chains which are held together by van der Waals interactions. The conformation of the substituents at position 6 of the triazine ring is such that the torsion angle is close to 0° for both independent molecules of the asymmetric unit.     

Synthesis and crystal structure of (Z)-1-(phenylsulphenyl)-2-phenylethenyl p-toluenesulfonate

The reaction between 1-phenylsulphenyl-2-phenylethyne and p-toluenesulfonic acid in methylene chloride gives (Z)-1-(phenylsulphenyl)-2-phenylethenyl p-toluenesulfonate (1) in good yields. This reaction is both a regio- and a stereospecific cis addition, confirmed by X-ray crystal structure analysis of the title compound. 1 crystallizes in the monoclinic space group P2₁/n with the lattice parameters a = 10.556(3), b = 9.730(3), c = 19.687(3) Å, = 105.05(2)°, V = 1952.7(8) ų, and Z = 4. The results of elemental analysis, IR and NMR spectroscopy are included.