Specific C-H...N intramolecular interaction in 1-vinyl-2-cyanoethylthiobenzimidazole with the formation of a nine-membered intramolecular ring,according to1H and13C NMR data

In the¹H NMR spectrum of 1-vinyl-2-cyanoethylthiobenzimidazole, an abnormal downfield shift has been found in the signal of the -hydrogen atom of the vinyl group, and also an increase in the corresponding direct¹³C-¹H spin-spin coupling constant, in comparison with other 2-substituted benzimidazoles. This indicates a specific C-H...N intramolecular interaction in this molecule between the -hydrogen atom and the cyano nitrogen atom, forming a nine-membered intramolecular ring.Translated from Translated from Izvestiya Akademii Nauk SSSR No. 10, pp. 2285–2288, October, 1991.     

Multinuclear NMR (1H,13C,15N,17O) studies of intramolecular interactions in 1-vinylpyridones and quinolones

¹H and¹³C NMR was used to estimate the dihedral angles between the planes of the vinyl group and the hetero ring for 1-vinylpyridones and quinolones. The¹H,¹³C,¹⁵N, and¹⁷O NMR data showed the existence of a specific intramolecular weak hydrogen bond between the -H atom of the vinyl group and the O atom in 1-vinyl-2-pyridones and 2-vinyl-1-isoquinolone.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1539–1547, July, 1990.     

1-Methyl-2(3,4)-(1-vinylpyrrol-2-yl)pyridinium iodides: some structural features revealed by 1H and 13C NMR spectroscopy

The reactions of 2-, 3-, and 4-(1-vinylpyrrol-2-yl)pyridines with methyl iodide afford the corresponding quaternary salts. Analysis of their ¹H and ¹³C NMR spectra showed that the quaternization of the nitrogen atom considerably enhances the -acceptor effect of the pyridine ring on the pyrrole ring and on the vinyl group. 1-Methyl-2-(1-vinylpyrrol-2-yl)pyridinium iodide contains no weak intramolecular C--H...N hydrogen bond present in the starting compound.     

Determination of the structure of 7-diethylamino-4-(1,2,3-triazol-1-yl)-2H-1-benzopyran-2-one derivatives using two-dimensional heteronuclear chemical-shift correlated NMR techniques

¹H and¹³C NMR spectra of 7-diethylamino-4-(1,2,3-triazol-1-yl)-2H-1-benzopyran-2-one derivatives have been studied. The location of the substituent in the 1,2,3-triazole ring was determined by the 2D COLOC method. It was established that the H(3) and H(5) protons in the coumarin moiety experience anisotropic influence of the phenyl subsituent at the C(5) atom in the triazole ring.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1330–1332, July, 1994.     

2D-NMR: Part VI. 2D-INADEQUATE spectral analysis and crystal structure of tricyclo[7.3.1.02,7]tridecane

2-Hydroxy-13-oxo-tricyclo[7.3.1.0^2,7]tridecane derivatives can be obtained by reaction of cyclohexanone with alcohols under alkaline conditions. The unambiguous assignment of all signals of the¹H-NMR- and¹³C-NMR-spectrum is possible by 2D-¹H-¹³C-shift correlation and 2D-INADEQUATE. Compound1 crystallizes in space group P2₁/n witha=8.518 (1),b=14.789 (2),c=19.321 (2) Å, =94.91 (1)°,Z=8,D _c =1.22 Mg cm^–3. The structure refined toR=0.100 andR _w =0.097 for 1719 observed reflections. Two independent molecules form centrosymmetric hydrogen-bonded dimers.Part V:Haslinger E.,Kalchhau-ser H.,Robien W.,Steindl H., Monatsh. Chem.115, 597 (1984).     

Ion-molecular interactions and the equilibrium composition in the HCl-1-methyl-2-pyrrolidone-1,1,2,2-tetrachloroethane system according to IR spectroscopy data

Multiple Attenuated Total Reflectance (MATR) IR spectra of solutions of HCl in 1-methyl-2-pyrrolidone (N-MP) (0–43.4 % HCl) were studied in the 900–4000 cm^–1 range. Spectra were recorded for theN-MP-HCl-1,1,2,2-tetrachloroethane (TCE) ternary system at a TCE N-MP ratio of 1 1. Depending on the ratio between the components, complexes of the compositionN-MP · HCl (C-1),N-MP · 2HCl (C-2), and 2N-MP · HCl (C-3) are formed in the system. Complex C-1 has a quasiionic structure, (CH₂)₃N(Me)CO...H...Cl, formed by a strong quasisymmetrical H-bond between the carbonyl O atom and the Cl atom. The addition of anN-MP molecule to complex C-1 yields complex C-3, in which the quasiionic character of the bond betweenN-MP and HCl is retained. When excess HCl is present, the quasiionic structure is destroyed, theN-MP molecule is protonated, and the Cl^– anion interacts with HCl to give an ion with a strong symmetrical H bond (Cl...H...Cl)^–. Complex C-2 is an ion pair.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1757–1763, September, 1995.This work was carried out with financial support of the Russian Foundation for Basic Research (Project No. 93-03-18356).     

Spectroscopic effects and intramolecular interactions in the1H and13C NMR spectra of five-membered N-vinyllactams

In 1-vinylpyrrolidone, 1-vinyl-1,2,4-triazole-5-ones, 1,3-divinylimidazolidine-2-thione, and 1-vinylbenzimidazole-1-thione the vinyl groups exist predominantly in the s-trans-, but in 1-vinyl-4,5-diphenylimidazole-2-ones in the s-cis(0)-conformations relative to the exocyclic heteroatom. In 1-vinylbenzimidazole-2-ones, 3-vinylbenzoxazole-2-one, and 1-vinylindole-2,3-diones the vinyl group is present as a mixture of the s-cis(0)- and s-trans(0)-conformations. According to¹H and¹³C NMR results there are specific intramolecular interactions in 1-vinylpyrrolidone and in 1,3-divinylimidazolidine-2-thione resembling weak hydrogen bonding between the -hydrogen atoms of the vinyl group and the oxygen or the sulfur atom. In 1-vinylsuccinimide, 2-vinylphthalimide, and 1,3-divinyl-4,5-diphenylimidazole-2-one there is the same type of interaction with the -cis-hydrogen atom of the vinyl group, while in 1,3-divinyl-1,2,4-triazole-5-one there is interaction between the same hydrogen atom and the nitrogen atom.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1983–1990, September, 1990.     

Nitropyrazoles

The structures of substitutedN-aminonitropyrazoles and 1- and 2-amino-4-nitro-1,2,3-triazoles as well as the site of protonation of 1-aminopyrazole were determined based on the¹H,¹³C, and¹⁵N (¹⁴N) NMR spectra. The¹³C NMR spectra were recorded under conditions of¹³C-{¹H,¹⁴N} triple resonance. Effects of substituents in the pyrazole ring on the¹³C and¹⁴N chemical shifts were studied. The¹³C,¹H and¹⁵N,¹H spin-spin coupling constants, obtained using techniques of [¹H]¹³C and [¹H]¹⁵N polarization transfer (SPT, INEPT), were measured, fully assigned, and discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2181–2186, November, 1995.For Part 8, see Ref. 1.     

Intramolecular C-H...N interactions in 1-vinyl- and 1,1′-divinyl-2,2′-biimidazolyls according to the data of1H and13C NMR

The specific intramolecular interaction between the -proton of the vinyl group and the pyridine nitrogen atom of the second imidazole ring, similar to the hydrogen bond, is accomplished in 1-vinyl- and 1,1-divinyl-2,2-biimidazolyls. In 1-vinyl-2,2'-biimidazolyl, the available NH-proton of the 2'-imidazole ring is localized at the nitrogen atom in the anti orientation in relation to the vinyl group.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2747–2750, December, 1990.     

Functional polymers. XII: Synthesis and polymerization of 2(2-vinyl-4-hydroxyphenyl)2H-benzotriazole and 2(3-vinyl-4-hydroxyphenyl)2H-benzotriazole

Condensation of diazotizedo-nitroaniline with 3-ethylphenol or with 2-ethylphenol followed by reduction of the resulting azo compound with zinc dust in sodium hydroxide solution gave 2-(2-ethyl-4-hydroxyphenyl)2H-benzotriazole and 2(3-ethyl-4-hydroxyphenyl)2H-benzotriazole, respectively. The individual compounds were acetylated, brominated withN-bromosuccinimide to the corresponding 1-bromoethyl compounds which were then dehydrobrominated with triethyl amine in acetonitrile and hydrolyzed to 2(2-vinyl-4-hydroxyphenyl)2H-benzotriazole or 2(3-vinyl-4-hydroxyphenyl)2H-benzotriazole. The two monomers could be polymerized and copolymerized with styrene and methyl methacrylate. The ethyl as well as the vinyl compounds and the corresponding polymers, when tested, are ineffective as ultraviolet absorbers as they have structures of 4-hydroxyphenyl rather than 2-hydroxyphenyl compounds with respect to the benzotriazole ring. A careful NMR analysis for the correct structural assignment is also described.Part XI:S. Yoshida andO. Vogl, Makromol. Chem., in press.     

Extraction and spectrophotometric determination of titanium(IV) withN 1-hydroxy-N 1,N 2-diphenylbenzamidine and thiocyanate

A precise, reliable, sensitive, and selective method for the determination of titanium(IV) is described. Titanium(IV) reacts withN ¹-hydroxy-N ¹,N ²-diphenylbenzamidine (HDPBA) and thiocyanate to form an orange-coloured mixed-ligand complex of stoichiometry 112 (Ti SCN^– HDPBA). The complex is quantitatively extractable into toluene from 0.05–0.15M hydrochloric acid. The spectrum of the complex exhibits an absorption maximum at 400 nm with a molar absorptivity of 20000M ^–1 cm^–1 and the coloured system obeys Beer's law in the concentration range 0.20–3.0 gml^–1 titanium. The effects of foreign ions and of various experimental parameters have been studied to establish the optimum conditions for the extraction and determination of titanium. The precision of the method has been evaluated and the relative standard deviation has been found to be 0.53%. The method has been successfully applied to the determination of titanium in synthetic matrices corresponding to titanium-containing ores, minerals, and alloys.     

Structural and spectral studies of 3-(2-hydroxyphenylimino)-1-phenylbutan-1-one and its diorganotin(IV) complexes

Two diorganotin(IV) complexes of the general formula R₂Sn[Ph(O)CCH-C(Me)N-C₆H₄(O)] (R = Ph, 1a; R = Me, 1b) have been synthesized from the corresponding diorganotin(IV) dichlorides and the ligand, 3-(2-hydroxyphenylimino)-1-phenylbutan-1-one (1) in methanol at room temperature in presence of triethylamine. Both compounds have been characterized by elemental analyses, IR and ¹H, ¹³C, ¹⁵N, ¹¹⁹Sn NMR spectra. The structures of the free ligand and the complexes have been confirmed by single crystal X-ray diffraction. There are three independent molecules in the crystal structure of the ligand 1 and in all three the O-bound proton is transferred to the imine nitrogen and makes an intramolecular N-H?O hydrogen bond with the carbonyl oxygen. In turn this makes an intermolecular hydrogen bond with the phenolic H atom. The crystal structure of 1 is trigonal and a new polymorph; triclinic and monoclinic forms have already been published. In 1a, the central tin atom adopts distorted trigonal-bipyramidal coordination geometry whereas in dimeric 1b it is distorted octahedral when including the intermolecular Sn-O(phenolic) bond [2.7998(20) Å]. The δ (¹¹⁹Sn) values for the complexes 1a and 1b are −306.6 and −127.9 ppm, respectively, thus indicating penta-coordinated Sn centres in solution.     

Synthesis and structure of azomethines based onN-vinyl derivatives of 2-amino- and 2-formylimidazoles

New Schiff's bases of theN-vinylimidazole andN-vinylbenzimidazole series were synthesized.¹H NMR data suggest that the azomethines exist in theE-form with respect to the CH=N bond and that the vinyl groups havetrans-orientation relative to each other. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 10, pp. 1857–1859, October, 1997.     

Molecular structure and spectroscopic properties of N-methylmorpholine betaine complex with 4-hydroxybenzoic acid

Crystal structure of the 1:1 complex of N-methylmorpholine betaine (MMB) with 4-hydroxybenzoic acid (4-HBA) has been determined by X-ray diffraction. Crystals are orthorhombic, space group Pna2₁ with a=7.933(2), b=15.336(3), and Z=4, R=0.033. The acid molecule forms two O-H?O hydrogen bonds with two betaine molecules. The COOH group of the acid forms shorter hydrogen bond with betaine (2.587(2) Å), than the hydroxyl group (2.677(2) Å). The carbonyl oxygen atom of the acid also interacts with the methylene hydrogen atom of the betaine through C-H?O hydrogen bond (3.256(2) Å). Thus formed infinite chains parallel to the z axis are connected by other C-H?O hydrogen bonds into layers perpendicular to the x axis. The morpholine ring has a chair conformation with the methyl group in the equatorial position and CH₂COO⁻ group in the axial one. The powder FTIR and Raman spectra and semiempirical calculations of the isolated molecule confirm the structure of the complex investigated. The ¹H and ¹³C spectra indicate that in DMSO-d₆ solution, protons are not transferred from the acid to the betaine molecules.     

Molecular miscible blend of poly(2-cyano-1,4-phenyleneterephthalamide) and polyvinylpyrrolidone characterized by two-dimensional correlation FTIR and solid state C NMR spectroscopy

Miscibility of blends of poly(2-cyano-1,4-phenyleneterephthalamide/polyvinylpyrrolidone) (CN-PPTA/PVP) was investigated by dilute solution viscometry, two-dimensional (2D) correlation Fourier transformed infrared (FTIR) spectroscopy and solid state ¹³C NMR spectroscopy. It was shown that a large proportion of the PVP, the water-soluble component, could not be removed from CN-PPTA by extraction with water, and even with boiling water for blend films, suggesting that the flexible aliphatic PVP chain forms a blend with the rigid aromatic CN-PPTA chain through strong intermolecular interaction making it too difficult to dissolve even in boiling water. Viscometry on a polymer mixture of dilute solution showed that [η]_exp exhibited larger value than [η]_theo in all mixtures used in this experiment, suggesting occurrence of a strong attractive interaction between the two polymers. 2D correlation FTIR spectroscopy revealed that the carbonyl absorption band of PVP at 1675 cm⁻¹ shifted to a new low frequency absorption band at 1640 cm⁻¹ with a change of 35 cm⁻¹, suggesting strong hydrogen bonding with NH (amide II) proton of CN-PPTA. Another new absorption band at 1685 cm⁻¹ was due to the carbonyl absorption band of CN-PPTA shifting to a higher frequency than that at 1662 cm⁻¹, indicating that some of the carbonyl groups in the CN-PPTA components of the blends were in a free state or in a non-hydrogen bonded state as a consequence of the participation of NH proton of CN-PPTA in hydrogen bonding, resulting in the absorption bands of NH bend deformation of CN-PPTA at 1542 and 1313 cm⁻¹ being shifted to higher wavenumber of 1556 and 1324 cm⁻¹, respectively. Solid state ¹³C NMR spectroscopy revealed a chemical shift for CO of the PVP component in the blend fiber changing down-field (shift to left) at 177.346 ppm with a difference of 1.812 ppm; this was due to a lower electron density around the carbon atom of CO of lactam via hydrogen bonding with NH proton of amide in the CN-PPTA component, suggesting that a homogeneous blend of the CN-PPTA and PVP was produced on a molecular scale via hydrogen bonding.     

Predissociation lifetime of the 1σ g 2 2σ g diabatic state of He 2 + : a one-channel approach

Summary This work is concerned with the application of a one-channel model to obtaining predissociation lifetimes and transition rates in a system of crossing diabatic states. The calculation focuses on the first shape resonance of the 1 _g ² 2 _g diabatic state of He ₂ ⁺ , which is relatively stable with respect to tunneling. This resonance predissociates as a result of the 1 _g ² 2 _g state being crossed by the 1 _g 1 _u ² dissociative diabatic state near the resonance level. We have estimated its predissociation lifetime to be of the order of 10^–11 s.     

A note on the electronic structure of O 2 −

Summary The electronic spectrum of O ₂ ^– is reinvestigated using CASSCF and CI methods. In particular, a previously noted curious flattening of theA ² _u curve has been studied in detail. The present analysis disagrees with the previous one where this flattening was found to be a result of an avoided curve crossing between a valence and a Rydberg state of O ₂ ^– . A simple procedure is suggested to determine whether a wavefunction is of real Rydberg character or if the bound character of the state is just an artefact of the calculation.     

New structural aspects of 3-vinyl-1H-indoles for predicting the outcome of Diels-Alder reactions

Summary Some selected 3-vinyl-1H-indoles have been synthesised and the first¹³C-NMR studies performed; in addition He(I) photoelectron spectra and the results of perturbation MO calculations of some examples of this class of compounds are presented. The molecular characteristics obtained thereby can be used to predict the results of [4s+2s]-cycloaddition reactions with 3-vinylindoles.

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Neue strukturelle Aspekte von 3-Vinylindolen zur Vorhersage der Reaktionsergebnisse bei Diels-Alder-Reaktionen

Zusammenfassung An selektiv synthetisierten 3-Vinyl-1H-indolen werden erstmals¹³C-NMR-spektroskopische Studien durchgeführt und exemplarisch an einigen Vertretern dieser Strukturklasse He(I)-Photoelektronenspektren sowie Ergebnisse von Störungs-MO-Rechnungen vorgestellt. Die daraus gewonnenen Moleküleigenschaften können zur Vorhersage des Reaktionsausganges von [4s+2s]-Cycloadditionen mit 3-Vinylindolen verwendent werden.

     

Stereochemicai study of 7-aryl-1,7,8,8a-tetrahydro-3(2H)indolizinones by1H and13C NMR

Stereochemistry of 7-aryl-1,7,8,8a-tetrahydro-3(2H)-indolizinones was studied by¹H and¹³C NMR. Complete assignment of¹H NMR signals and analysis of¹H-¹H coupling constants were performed using the iterative PANIC program. Values of³ J _6,7,³ J _7,8endo, and⁴ J _5,7 allow one to unambiguously identify the correspondingexo- andendo-stereoisomers. For stereoisomers with exo-orientation of H(7), complete assignment of¹³C NMR signals was performed on the basis of analysis of the¹³C-¹H coupling constants using two dimensional heteronuclear shift-correlating spectroscopy.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 591–593, March, 1996.