Investigation of 2-(3,4-dimethoxyphenyl)-5,6-dimethoxy-1H-indene by X-ray crystallography and NMR spectroscopy

2-(3,4-Dimethoxyphenyl)-5,6-dimethoxy-1H-indene (obtained by acid treatment of 1,2-bis(3,4-dimethoxyphenyl)-1,3-propanediol) crystallizes in space groupP2₁/c witha=6.836(6),b=28.631(9),c=16.344(6) Å, =95.73(5)°, andZ=8. There are two molecules in the asymmetric unit; the conformations of these molecules exhibit minor differences. In the crystals the double bond in the five-membered ring of the compound is disordered over two positions. The nature of the bonds in the five-membered ring could be ensured by¹H-NMR and¹³C-NMR spectral examinations.     

Investigation of lignin models of the biphenyl type by X-ray crystallography and NMR spectroscopy

Lignin models of the biphenyl type have been synthesized and crystal structures of two of them have been determined. The tetraacetate of 5,5-bis(hydroxymethyl)-3,3-dimethoxy-2,2-biphenyldiol crystallizes in space group witha=11.319(2),b=12.232(6),c=9.242(3) Å, =101.66(3)°, =108.14(2)°, =79.08(2)° andZ=2.R=0.036 (2720 observed [I>3(I)] reflections). The acetate of 5,5-di-tert-butyl-2,3,3-trimethoxy-2-biphenylol crystallizes in space group witha=11.972(2),b=21.621(3),c=9.834(1) Å, =91.18(1)°, =113.13(1)°. =98.42(1)°, andZ=4.R=0.050 (8129 observed [I>3(I)] reflections).¹H NMR and¹³C NMR data for the above-mentioned compounds and a third model, the diacetate of 5,5-bis(1-hydroxyethyl)-2,2,3,3-tetramethoxybiphenyl, are reported. Observed signal positions are compared with those calculated on the basis of crystal structure data. The possibilities to obtain structural information about biphenyl structures in lignins from NMR spectra are discussed.     

Investigation of an inclusion compound of trans-1,3-bis(3,4-dimethoxyphenyl)-2,3-epoxy-1-propanone with chloroform by NMR spectroscopy and X-ray crystallography

trans-1,3-Bis(3,4-dimethoxyphenyl)-2,3-epoxy-1-propanone crystallizes in a monoclinic form (m.p. 155–156°C, from ethanol) and a trigonal form (m.p. 125–126°C, from chloroform/hexane or chloroform). NMR studies revealed that chloroform is present in the crystals of the trigonal form (epoxide/chloroform ratio 3:1). Solid-state NMR experiments showed that the trigonal form was gradually converted into the monoclinic form on storage in vacuo. On the basis of NMR and X-ray examinations it was concluded that the trigonal form is an inclusion compound of trans-1,3-bis(3,4-dimethoxyphenyl)-2,3-epoxy-1-propanone with chloroform. The crystal structure of the trigonal form with space group of R , a = 36.0354(4), c = 8.2743(2) Å, and Z = 18, has been refined to R = 0.0506 by the employment of the SQUEEZE procedure implemented in PLATON-94.     

Crystal structure and spectroscopy of 4-N-benzylaminocoumarin

The structure of 4-N-benzylaminocoumarin (C₁₆H₁₃NO₂) has been determined by X-ray diffraction and the Ft-ir,¹H- and¹³C-nmr spectra of the compound were recorded. Crystals of the compound are monoclinic, space group P2₁/c, with cell dimensiona=8.077(2),b=14.598(4),c=10.890(3) Å, and =97.76(3)°. The Ft-ir and nmr spectra indicate that the nitrogen atom is in the amino form in solution. The crystal structure is consistent with this observation, but the C(3)–C(4) double bond is clearly delocalized to include the lone pair on the nitrogen atom.     

Helical chirality of 1-phenacyl-1,10-phenanthrolinium bromides

Evidence for non-coplanarity of the pyridine and pyridinium rings in a series of 1-phenacyl-1,10-phenanthrolinium bromides was gleaned from ¹H-NMR data recorded in DMSO-d ₆ solution. The X-ray structure of 1-(4-chlorophenacyl)-1,10-phenanthrolinium bromide, as representative of this series, was determined in order to establish whether such a molecular distortion occurs in the solid state. The title compound crystallizes in the space group C2/c as a sesquihydrate of formula C₂₀H₁₄BrClN₂O·1.5H₂O with a = 35.7348(3) Å, b = 5.3468(1) Å, c = 21.7312(2) Å, = 116.4076(4)° and Z = 8. In the crystal, the helical chirality is manifested as a pronounced twist in the phenanthrolinium moiety, with the pyridine and pyridinium rings inclined at 6.8(2)°. This distortion is attributed to intramolecular hydrogen bonding of type C–H···N involving the methylene group and the uncharged nitrogen atom of the phenanthrolinium moiety. In the crystal, the cations surround an intricate array of water molecules and bromide ions held together by O–H···Br^– hydrogen bonds and comprising infinite chains ···Br^–···H–O–H···Br^–···, cross-linked by water molecules.     

Structure Effect of Solute on Orientational Order in Binary Mixture by 2H-NMR and Molecular Simulations

Abstract

The orientational order parameters of six solutes with different shapes and sizes dissolved in two nematic solvents have been measured as a function of temperature. The parameter, S^xx-S^yy is correlated with the molecular geometrical structure, while S^zz is affected by not only the geometry but also the anisotropy in the polarizability. The molecular dynamics simulations are carried out using a realistic atom-atom potential for evaluating the ordering properties in the nematic phase. The results provide reasonable values of S^zz corresponding to experimental ones for solutes and solvents, and also a prediction of uniaxiality for the nematic phase.     

Synthesis,spectral, X-ray diffraction and DFT studies on 1-(2-methyl-2-propenyl)-3-(2,3,4,5,6-pentamethylbenzyl)benzimidazolium chloride hydrate

A new benzimidazole based N-heterocyclic carbene (NHC) salt (1) was synthesized by the reaction of benzimidazole precursor with alkyl halide. The structure of 1 was determined by elemental analysis, FT-IR, ¹H NMR and ¹³C NMR spectroscopy tecniques and X-ray crystallography. The compound crystallized in the triclinic space group P-1 with two molecules in the unit cell. The optimization of 1 was firstly performed at B3LYP/6-311G++(d,p) level, then the theoretical spectral studies performed and compared with the experimental values. Besides the frontier molecular orbital energies and chemical reactivity analysis of 1, together with the electrostatic potential and molecular electrostatic potential analyses were performed at the same level of theory.     

Helical chirality of pyrrolo[1,2-a][1,10]phenanthroline derivatives

The objective of the study was to confirm by X-ray analysis the phenomenon of helical chirality inferred from solution ¹H-NMR data for a series of derivatives based on the novel pyrrolo[1,2-a][1,10]phenanthroline system. The syntheses of the title compounds and their ¹H-NMR data are presented. Crystals of the representative compound ethyl, 1-(4-phenylbenzoyl)-pyrrolo[1,2-a][1,10]phenanthroline-3-carboxylate, with molecular formula C₃₁H₂₂N₂O₃, were found to crystallize in the triclinic system, space group P 1 with a = 7.8541(1), b = 11.2605(2), c = 13.4093(3) Å, = 92.244(1), = 90.292(1), = 106.475(1) and Z = 2. The X-ray analysis revealed the predicted helicity of the phenanthroline system as well as its origin, namely the proximity of the pyridine N atom and the carbonyl C atom of the phenylbenzoyl residue, with non-bonded distance N s C of only 2.465(2) Å. A secondary, but significant distortion, involving displacement of the carbonyl C atom by more than 0.5 Å from the pyrrole ring, was evident. The crystal structure is maintained by C–H s O hydrogen bonds and – interactions.     

Crystal and molecular structure of triphenyl[2-(p-tolylthio)ethyl]tin

The crystal and molecular structure of Ph₃SnCH₂CH₂SC₆H₄Me-p has been determined by X-ray crystallography. In each of the two independent molecules in the asymmetric unit the tin atom has an irregular tetrahedral geometry, with C–Sn–C valency angles ranging from 104.1(5) to 114.7(5)° in molecule (1) and from 104.6 to 112.7(6)° in molecule (2). The bond lengths, C_alkyl–Sn are 2.18(1) and 2.17(2)Å (in molecules (1) and (2), respectively) while the C_aryl–Sn bond lengths range from 2.11(1) to 2.13(1)Å in molecule (1) and from 2.09(1) to 2.14(1)Å in molecule (2). The Sn–C–C–S torsion angle, 172(1)° is the same for both molecules. NMR spectral data are presented; the¹H NMR spectrum in solution of the central-CH₂–CH₂-unit suggests that each of the protons on each of the CH₂ groups is magnetically distinct and that rotations about the C–C bond are slow on the NMR time scale. Comparisons with similar molecules are made and conformations discussed in terms of steric effects.     

X-ray structure and NMR assignment of 4,4′-[3-oxa-1,5-pentanedi(ylthio)]-3,3′-diquinolinyl sulfide

The title compound (C₂₂H₁₈N₂OS₃) is monoclinic, with a=20.7446(5), b=8.332(1), c=24.393(7)°, β=112.12(1)° and space group P2₁/n. There are two independent molecules in the unit cell. Two quinoline moieties are nearly perpendicular to each other (76.9(1)°) and (72.0(2)°). Both S-methylene fragments are trans-orientated with respect to the C(3)−S(1)−C(13) plane. Two pairs of sulfur atoms in ortho-positions are in very close contact with sulfide preserving a skew conformation. The central 12-membered ring adopts an unusual conformation. Part XLIII in the series of Azinyl Sulfides. Part XLII: Maślankiewicz, M.J.; Maślankiewicz, A.J. Heterocycl. Chem. 1996,33, 1989.     

Spectroscopic Studies and Crystal Structure of 3-[(2-morpholinoethylimino)methyl]benzene-1,2-diol

Abstract Schiff base 3-[(2-morpholinoethylimino)methyl]benzene-1,2-diol has been synthesized from the reaction of 4-(2-aminoethyl)morpholine with 2,3-dihydroxybenzaldehyde. The title compound has been characterized by elemental analysis, IR, ¹H-NMR, ¹³C-NMR and UV–visible techniques. The structure of the compound also has been examined crystallographically. For the compound exist as dominant form of enol-imines in both the solutions and solid state. The crystal structure has been solved by direct methods and refined by full-matrix least squares. The title compound crystallize in the monoclinic space group P2₁/n with a = 12.085(1), b = 8.256(1), c = 13.650(1) ?, β = 108.56(1)°, V = 1291.1(2) ?³, D _x = 1.288 g cm⁻³, respectively (R ₁ = 0.0336 and wR ₂ = 0.0922 for 2117 reflections [I > 2σ(I)]. Index abstract Intramolecular hydrogen bonding is important on the tautomeric properties and the type of aldehyde plays a vital role of the enol-imine and keto-amine properties of the Schiff base ligand.      

Preparation,spectral studies and X-ray crystal structure of 1,3,5-triphenyl-1,5-pentanedione,C23H20O2

1,3,5-triphenyl-1,5-pentanedione, C₂₃H₂₀O₂, has been prepared and characterized by spectroscopic methods and single crystal X-ray analysis. Crystals are monoclinic, space groupP2₁/n, a=28.124(4),b=5.997(1),c=10.434(1)Å, -98.42(1)Å,Z=4. The structure has been refined to a finalR-value of 0.040 for 1625 reflections withF _o>3(F _o). The compound contains the two carbonyl groups in a mutuallycis arrangement.     

Crystal structure of 3H-1,2-benzodithiol-3-one 1-oxide

The compound 3H-1,2-benzodithiol-3-one 1-oxide (2) has proven useful in modeling the reactivity of the novel antitumor antibiotic leinamycin (1). The crystal structure of this unusual sulfur heterocycle is reported here. The molecule crystallizes in the P-1 space group with cell parameters a = 7.168(4), b = 7.670(3), c = 7.922(3)Å, = 68.34(4), = 83.86(3), = 65.50(3),° and U = 367.8 ų.     

The hydrogen bonding in 2-amino-3-cyano-4-(3-nitrophenyl)-4,6-dihydro-5H-pyrano[3,2-c]quinolin-5-one N,N-dimethylformamide solvate monohydrate

The crystal structure of 2-amino-3-cyano-4,6-dihydro-4-(3-nitrophenyl)-5H-pyrano[3,2-c]quinolin-5-one N,N-dimethylformamide solvate monohydrate is determined by room temperature X-ray diffraction. The title compound 1, C₂₂H₂₁N₅O₆, is triclinic, space group P-1, a=9.109(2) ?, b=11.340(2) ?, c=12.485(2) ?, α=70.02(1)°, β=69.36(1)°, γ=67.32(1)°, Z=2, V=1081.4(4) ?³. It is interesting that a bridge-like hydrogen bond O–H···O is formed between the title compound and solvent molecules of water with molecular ratio of 2:2 building a bi-layer framework. In addition, there are two other types of classical hydrogen bonds N–H···N and N–H···O in the crystal structure.Supplementary material Crystallographic data for the structure reported in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication no. CCDC-275001. Copies of available material can be obtained, free of charge, on application to the Director, CCDC, 12 Union Road, Cambridge CB2 1EZ, UK, (fax: +44-(0) 1223–336033 or e-mail: deposit@ccdc.cam.ac.uk).     

Structure of 4-(2-chloro-4,5-dimethoxybenzylidene)-2-methyl-5-oxazolone. X-ray and NMR study

The azlactone of 6-chloroveratraldehyde 3 (4-(2-chloro-4,5-dimethoxybenzylidene)-2-methyl-5-oxazolone) was synthesized from 6-chloroveratraldehyde 2 and its structure investigated using X-ray crystallographic and nuclear magnetic resonance methods. Compound 3 crystallized in the P2₁/c (#14) space group (Z = 4) with cell dimensions a = 9.148(2), b = 22.938(2), c = 6.707(1) Å, and = 111.50(2)°. The X-ray study shows that azlactone 3 exists as the Z-isomer and crystallizes as a planar structure, i.e., both the phenyl and azlactone ring systems, as well as the functional groups attached to them, lie in the same plane. The ¹H and ¹³C NMR spectral values also support the formation of the Z-isomer only, during the synthesis of 4-(2-chloro-4,5-dimethoxybenzylidene)-2-methyl-5-oxazolone.     

The crystallographic structure of 4-hydroxy-3-methylene-4-(p-nitrophenyl)butan-2-one

The crystallographic structure of 4-hydroxy-3-methylene-4-(p-nitrophenyl)butan-2-one 1 is disclosed by x-ray analysis. It crystallized in the space group C2/c (#15) with a = 19.958(4), b = 10.486(3), c = 15.009(3) Å, = 137.553(6)°, V = 2120.0(9) Å,³ Dcalc = 1.386 g/cm³, and Z = 8.     

The preparation, characterization and X-ray structural analysis of tetrakis[1-methyl-3-(2-propyl)-2(3H)-imidazolethione]zinc(II) tetrafluoroborate and tetrakis[1-methyl-3-(1-butyl)-2(3H)- imidazolethione]zinc(II) tetrafluoroborate

Two compounds, [Zn(mipit)₄][BF₄]₂ (1) and [Zn(mnbit)₄][BF₄]₂ (2) have been synthesized and characterized via standard solid and solution state methods including single crystal X-ray crystallography (mipit: 1-methyl-3-(2-propyl)-2(3H)-imidazolethione and mnbit: 1-methyl-3-(1-butyl)-2(3H)-imidazolethione). Compound 1 crystallizes in monoclinic space group P2₁/n with a = 11.804(2) ?, b = 16.710(3) ?, c = 25.763(5) ?, γ = 90.14(3)° and Z = 4, whereas compound 2 crystallizes in tetragonal space group $${\rm I}\bar{4}$$ with a = b = 11.6517(16) ?, c= 16.820(3) ?, and Z = 2. Both complexes are high melting, colorless water soluble 2:1 electrolyte solids that state have flattened tetrahedral ZnS₄ coordination geometry. The isopropyl analog is slightly more distorted than the n-butyl analog, and the degree of distortion is not directly related to the steric bulk of the ligand.     

X-ray crystal structures of two polymorphic forms,monoclinic and triclinic,of: 1-[(<Emphasis Type="Italic">E</Emphasis>)-2-(4-bromophenyl)1-diazenyl]-3-({3-[(<Emphasis Type="Italic">E</Emphasis>)-2-(4-bromophenyl)-1-diazenyl]-6-ethylhexahydro-1-pyrimidinyl}methyl)-4-ethylhexahydropyrimidine

1-[(E)-2-(4-bromophenyl)-1-diazenyl]-3-({3-[(E)-2-(4-bromophenyl)-1-diazenyl]-6-ethylhexahydro-1-pyrimidinyl}methyl)-4-ethylhexahydropyrimidine (1) has been synthesized by reaction of a mixture of formaldehyde and 1,3-pentanediamine{DYTEK^®EPdiamine} with p-bromobenzenediazonium chloride. This compound crystallizes in two polymorphic forms 1-α and 1-β whose crystal structures have been determined by single crystal X-ray diffraction analysis. Both polymorphs 1-α and 1-β display crystallographic disorder within the hexahydropyrimidine rings. The molecule of 1 is built up of two equivalent 3-(aryldiazenyl)-6-ethylhexahydro-1-pyrimidinyl groups in the s-trans orientation around the central methylene group (C13). In both structures the triazene moieties adopt the anti configuration around the N=N bonds, displaying significant π-conjugation. The crystal packings are determined only by van der Waals interactions. The crystal structures of 1-α and 1-β are compared with the previously reported structure of the 5,5-dimethylhexahydropyrimidine analogue 3. Compounds 1 and 3 are isomeric with respect to the hexahydropyrimidine moiety. The structures of 1 and 3 are very different in one respect; in 1 the aryldiazenyl-hexahydropyrimidinyl groups are in the s-trans orientation around the central methylene group, whereas in 3 the arrangement of the aryldiazenylhexahydropyrimidinyl groups is the s-cis orientation. Crystal data: 1-α C₂₅H₃₄N₈Br₂, monoclinic, space group P2(1)/c, a = 9.2150(3), b = 19.4059(6), c = 15.4324(5) Å, β = 98.738(1)^°, V = 2727.7(2) ų, for Z = 4; 1-β C₂₅H₃₄N₈Br₂, triclinic, space group P-1, a = 9.6009(3), b = 10.7509(4), c = 14.2169(5) Å, α = 99.830(2), β = 105.973(3), γ = 95.578(1)^°, V = 1373.9(1) ų, for Z = 2.     

Stereoselective Synthesis and X-Ray Structure Determination of Labeled [1, 2, 3-<Superscript>13</Superscript>C<Subscript>3</Subscript>]-1-(Phenylsulfinyl)-3-Benzyloxyacetone

[1,2,3-¹³C₃]-1-(Phenylsulfinyl)-3-benzyloxyacetone, C₁₆H₁₆O₃S, (3) has been synthesized and its crystal structure has been determined by a single-crystal X-ray diffraction analysis. The X-ray diffraction study revealed that compound 3 crystallizes in the monoclinic crystal system in the acentric space group Pc, with cell constants at T = 100 K: a = 16.073(5), b = 5.5079(16), c = 7.949(2) Å, β = 100.221(4)^°, V = 692.6(3) ų, Z = 2, d _calc = 1.383 g/cm³. Compound 3 contains the chiral tetravalent three-coordinated sulfur atom, which has a distorted tetrahedral configuration with a lone electron pair occupying one of the tetrahedron vertices. In the crystal, the molecules are packed in stacks along the b axis; the stacks consist of the molecules of the same chirality. Furthermore, the stacks of the molecules of the opposite chirality alternate along the c axis. The molecules in neighboring stacks are arranged by head-to-tail orientations. There are no short intermolecular contacts in the crystal of 3.