Inhibiting low-frequency vibrations explains exceptionally high electron mobility in 2,5-difluoro-7,7,8,8-tetracyanoquinodimethane (f2-tcnq) single crystals / I. Y. Chernyshov, M. V. Vener, E. V. Feldman et al. // Journal of Physical Chemistry Letters. — 2017. — Vol. 8, no. 13. — P. 2875–2880. [ DOI ]
Peroxosolvates: formation criteria, h2o2 hydrogen bonding, and isomorphism with the corresponding hydrates / I. Y. Chernyshov, M. V. Vener, P. V. Prikhodchenko et al. // Crystal Growth and Design. — 2017. — Vol. 1, no. 17. — P. 214–220.
The role of london dispersion interactions in strong and moderate intermolecular hydrogen bonds / S. A. Katsyuba, M. V. Vener, E. E. Zvereva, J. G. Brandenburg // Chemical Physics Letters. — 2017. — Vol. 672. — P. 124–127. Two variants of density functional theory computations have been applied to characterization of hydrogen bonds of the 1-(2-hydroxylethyl)-3-methylimidazolium acetate ([C2OHmim][OAc]), i.e. with and without inclusion of dispersion interactions. A comparison of the results demonstrates that London dispersion interactions have very little impact on the energetical, geometrical, infrared spectroscopic and electron density parameters of charge-assisted intermolecular hydrogen bonds functioning both in the crystal of the [C2OHmim][OAc] and in the isolated [C2OHmim]+ [OAc] ion pairs. [ DOI ]
Weak interactions cause packing polymorphism in pharmaceutical two-component crystals. the case study of the salicylamide cocrystal / A. O. Surov, A. N. Manin, A. P. Voronin et al. // Crystal Growth and Design. — 2017. — Vol. 17. — P. 1425–1437. Two polymorphs of the salicylamide cocrystal with oxalic acid have been obtained and described. Form I of the cocrystal was prepared by three alternative methods in various solvents, while formation of form II was achieved only by a special crystallization procedure. Single-crystal X-ray analysis has revealed that polymorphs consist of conformationally identical salicylamide and oxalic acid molecules, which are assembled into supramolecular units connected via a network of very similar hydrogen bonds. The packing arrangements of the cocrystal polymorphs, however, were found to be different, suggesting a rare example of packing polymorphism. The stability relationship between the polymorphs has been rationalized by using a number of experimental methods, including thermochemical analysis, solubility, and solution calorimetry measurements. Similarities and differences in intermolecular contacts across two polymorphs have been visualized using the Hirshfeld surface analysis. The Bader analysis of the theoretical electron density has enabled us to quantify the pattern of noncovalent interactions in the considered cocrystals. Applicability of different theoretical schemes for evaluation of the lattice energy of the two-component organic crystals has been discussed. [ DOI ]
Voronin A. P., Perlovich G. L., Vener M. V. Effects of the crystal structure and thermodynamic stability on solubility of bioactive compounds: Dft study of isoniazid cocrystals // Computational & theoretical chemistry. — 2016. — Vol. 1092. — P. 1–11. Intrinsic solubility of the isoniazid-carboxylic acid cocrystals is explored using thermodynamic cycle of transferring from crystal to gas and then to solution. The enthalpy/Gibbs free energy of phase transitions is computed by solid-state DFT (crystal) and DFT methods with/without accounting for polar solvent (aqueous solution/gas). The dissolution process of the isoniazid-dicarboxylic acid 2:1 cocrystals is foundto be enthalpy-determined. The linear correlation between the theoretical sublimation enthalpies andexperimental Gibbs energy of solution is established. According to it, the increase of stability causes the decrease of the considered cocrystals solubility. We conclude that a soluble and relatively stable cocrystal of isoniazid should be characterized by the sublimation enthalpy varying from 185 to 200 kJmol-1. Bader analysis of theoretical periodic electron density enables us to quantify the noncovalent interactions and clarify their role in formation of the isoniazid cocrystals. The sublimation enthalpy of the cocrystals is defined by the structure of the coformer molecule. Its value is less 150 kJmol-1 in the case of aromatic acids and larger than 180 kJmol1 for the aliphatic dicarboxylic acids. The sublimation enthalpy increases with the increase of the dicarboxylic acid hydrocarbon chain. [ DOI ]
Peroxosolvates: Formation criteria, h2o2 hydrogen bonding, and isomorphism with the corresponding hydrates / I. Y. Chernyshov, M. V. Vener, P. V. Prikhodchenko et al. // Crystal Growth and Design. — 2016. — Vol. 17, no. 1. — P. 214–220. [ DOI ]
Spectral features of guanidinium-carboxylate salt bridges. the combined atr-ir and theoretical studies of aqueous solution of guanidinium acetate / E. O. Levina, B. V. Lokshin, B. D. Mai, M. V. Vener // Chemical Physics Letters. — 2016. — Vol. 659. — P. 117–120. The spectrum of guanidinium acetate in aqueous solution has been recorded by attenuated total reflectance infrared spectroscopy (ATR-IR). Assignments of the bands have been done using the polarizable continuum model (PCM). Three IR intensive bands at 1670, 1550, and 1410 cm-1 are associated with stretching and bending vibrations of the groups forming a ring of six heavy atoms of the bidentate configuration of guanidinium acetate. The relatively weak broad band near 2200 cm-1 is tentatively assigned to the stretching vibration of the N-H...O fragment of the hydrogen-bonded ion pairs. [ DOI ]
ОСОБЕННОСТИ КОНТАКТНОЙ ИОННОЙ ПАРЫ ГУАНИДИН-АЦЕТАТ В ВОДЕ. ИССЛЕДОВАНИЕ МЕТОДАМИ НПВО И ТЕОРИИ ФУНКЦИОНАЛА ПЛОТНОСТИ / М. В. Венер, В. Н. Попов, Б. З. Май, Б. В. Локшин // Вестник Воронежского государственного университета. Серия: Химия. Биология. Фармация. — 2016. — № 3. — С. 58–62.
Influence of secondary interactions on the structure, sublimation thermodynamics and solubility of salicylate:4-hydroxybenzamide cocrystals combined experimental and theoretical study / A. N. Manin, A. P. Voronin, A. V. Shishkina et al. // Journal of Physical Chemistry B. — 2015. — Vol. 119. — P. 10466–10477. Cocrystal screening of 4-hydroxybenzamide with a number of salicylates (salicylic acid, SA; 4-aminosalicylic acid, PASA; acetylsalicylic acid, ASA; and salicylsalicylic acid, SSA) was conducted to confirm the formation of two cocrystals, [SA+4-OHBZA] (1:1) and [PASA+4-OHBZA] (1:1). Their structures were determined using single-crystal X-ray diffraction, and the hydrogen-bond network topology was studied. Thermodynamic characteristics of salicylic acid cocrystal sublimation were obtained experimentally. It was proved that PASA cocrystallization with 4-OHBZA makes the drug more stable and prevents the irreversible process of decarboxylation of PASA resulting in formation of toxic 3-aminophenol. The pattern of non-covalent interactions in the cocrystals is described quantitatively using solid-state density functional theory followed by Bader analysis of the periodic electron density. It has been found that the total energy of secondary interactions between synthon atoms and the side hydroxyl group of the acid molecule in [SA+4-OHBZA] (1:1) and [PASA+4-OHBZA] (1:1) cocrystals is comparable to the energy of the primary acid−amide heterosynthon. The theoretical value of the sublimation enthalpy of [SA+4-OHBZA], 231 kJ/mol, agrees fairly well with the experimental one, 272 kJ/mol. The dissolution experiments with [SA+4-OHBZA] have proved that the relatively large cocrystal stability in relation to the stability of its components has a negative effect on the dissolution rate and equilibrium solubility. The [PASA+4-OHBZA] (1:1) cocrystal showed an enhancement of apparent solubility compared to that of the corresponding pure active pharmaceutical ingredient, while their intrinsic dissolution rates are comparable. [ DOI ]
Potassium cesium and ammonium peroxogermanates with inorganic hexanuclear peroxo bridged germanium anion isolated from aqueous solution / A. G. Medvedev, A. A. Mikhaylov, A. V. Churakov et al. // Inorganic Chemistry. — 2015. — Vol. 54. — P. 8058–8065. Potassium, cesium ammonium and potassium ammonium peroxogermanates were isolated from 3% hydrogen peroxide aqueous solutions of the corresponding hydroxogermanates and characterized by single crystal and powder X-ray diffraction studies and by Raman spectroscopy and thermal analysis. The crystal structure of all three compounds consists of cations of potassium and/or ammonium and cesium, water molecules, and centrosymmetric hexanuclear peroxogermanate anion with six μ-oxo- and six μ-peroxo groups. Peroxogermanates demonstrate relatively high thermal stability: the peroxide remains in the structure even after water release after heating to 100−120 oC. DFT calculations of the peroxogermanate anion confirm its higher thermodynamic stability compared to the hydroperoxo- and oxogermanate analogues. [ DOI ]
Quantification of conventional and non-conventional charge-assisted hydrogen bonds in the condensed and gas phases / S. A. Katsyuba, M. V. Vener, E. E. Zvereva et al. // Journal of Physical Chemistry Letters. — 2015. — Vol. 6. — P. 4431–4436. Charge-assisted hydrogen bonds (CAHBs) play critical roles in many systems from biology through to materials. In none of these areas has the role and function of CAHBs been explored satisfactorily because of the lack of data on the energy of CAHBs in the condensed phases. We have, for the first time, quantified three types of CAHBs in both the condensed and gas phases for 1-(2′-hydroxylethyl)-3-methylimidazolium acetate ([C2OHmim][OAc]). The energy of conventional OH···[OAc]− CAHBs is ∼10 kcal· mol−1, whereas nonconventional C(sp2)H···[OAc]− and C(sp3)H···[OAc]− CAHBs are weaker by ∼5−7 kcal·mol−1. In the gas phase, the strength of the nonconventional CAHBs is doubled, whereas the conventional CAHBs are strengthened by <20%. The influence of cooperativity effects on the ability of the [OAc]− anion to deprotonate the imidazolium cation is evaluated. The ability to quantify CAHBs in the condensed phase on the basis of easier accessible gas-phase estimates is highlighted. [ DOI ]
Specific features of the extra strong intermolecular hydrogen bonds in crystals: Insights from the theoretical charge density analysis / M. V. Vener, E. O. Levina, A. A. Astakhov, V. G. Tsirelson // Chemical Physics Letters. — 2015. — Vol. 638. — P. 233–236. [ DOI ]
The applicability of the dimeric heterosynthon concept to molecules with equivalent binding sites. a dft study of crystalline urea / A. G. Medvedev, A. V. Shishkina, O. Lev et al. // RSC advances. — 2015. — Vol. 5. — P. 29601–29608.
The structure and ir signatures of the arginine-glutamate salt bridge. insights from the classical md simulations / M. V. Vener, A. V. Odinokov, C. Wehmeyer, D. Sebastiani // Journal of Chemical Physics. — 2015. — Vol. 142. — P. 215106. Salt bridges and ionic interactions play an important role in protein stability, protein-protein interactions, and protein folding. Here, we provide the classical MD simulations of the structure and IR signatures of the arginine (Arg)–glutamate (Glu) salt bridge. The Arg-Glu model is based on the infinite polyalanine antiparallel two-stranded β-sheet structure. The 1 μs NPT simulations show that it preferably exists as a salt bridge (a contact ion pair). Bidentate (the end-on and side-on structures) and monodentate (the backside structure) configurations are localized [Donald et al., Proteins 79, 898–915 (2011)]. These structures are stabilized by the short +N–H· · ·O− bonds. Their relative stability depends on a force field used in the MD simulations. The side-on structure is the most stable in terms of the OPLS-AA force field. If AMBER ff99SB-ILDN is used, the backside structure is the most stable. Compared with experimental data, simulations using the OPLS all-atom (OPLS-AA) force field describe the stability of the salt bridge structures quite realistically. It decreases in the following order: side-on > end-on > backside. The most stable side-on structure lives several nanoseconds. The less stable backside structure exists a few tenth of a nanosecond. Several short-living species (solvent shared, completely separately solvated ionic groups ion pairs, etc.) are also localized. Their lifetime is a few tens of picoseconds or less. Conformational flexibility of amino acids forming the salt bridge is investigated. The spectral signature of the Arg-Glu salt bridge is the IR-intensive band around 2200 cm−1. It is caused by the asymmetric stretching vibrations of the +N–H· · ·O− fragment. Result of the present paper suggests that infrared spectroscopy in the 2000–2800 frequency region may be a rapid and quantitative method for the study of salt bridges in peptides and ionic interactions between proteins. This region is usually not considered in spectroscopic studies of peptides and proteins. [ DOI ]
Evaluation of the lattice energy of the two-component molecular crystals using solid-state density functional theory / M. V. Vener, E. O. Levina, O. A. Koloskov et al. // Crystal Growth and Design. — 2014. — Vol. 14, no. 10. — P. 4997–5003. [ DOI ]
Nitranilic acid hexahydrate, a novel benchmark system of the zundel cation in an intrinsically asymmetric environment: hydrogen bond dynamics characterised by experimental and theoretical methods / K. Molčanov, J. Stare, M. V. Vener et al. // Physical Chemistry Chemical Physics. — 2014. — Vol. 16. — P. 998–1007. Nitranilic acid (2,5-dihydroxy-3,6-dinitro-2,5-cyclohexadiene-1,4-dione) as a strong dibasic acid in acidic aqueous media creates the Zundel cation, H5O2+. The structural unit in a crystal comprises (H5O2)2+(2,5-dihydroxy-3,6-dinitro-1,4-benzoquinonate)2 dihydrate where the Zundel cation reveals no symmetry, being an ideal case for studying proton dynamics and its stability. The Zundel cation and proton transfer dynamics are studied by variable-temperature X-ray diffraction, IR and solid-state NMR spectroscopy, and various quantum chemical methods, including periodic DFT calculations, ab initio molecular dynamics simulation, and quantization of nuclear motion along three fully coupled internal coordinates. The Zundel cation features a short H-bond with the O O distance of 2.433(2) Å with an asymmetric placement of hydrogen. The proton potential is of a single well type and, due to the non-symmetric surroundings, of asymmetric shape. The formation of the Zundel cation is facilitated by the electronegative NO2 groups. The employed spectroscopic techniques supported by calculations confirm the presence of a short H-bond with a complex proton dynamics. [ DOI ]
Salicylamide cocrystals: Screening, crystal structure, sublimation thermodynamics, dissolution and solid-state dft calculations / A. N. Manin, A. P. Voronin, N. G. Manin et al. // Journal of Physical Chemistry B. — 2014. — Vol. 118. — P. 6803–6814.
Vener M. V., Shenderovich I. G., Rykounov A. A. A qualitative study of the effect of a counterion and polar environment on the structure and spectroscopic signatures of a hydrated hydroxyl anion // Theoretical Chemistry Accounts. — 2013. — Vol. 132. — P. 1361. The results of the qualitative analysis of the effect of a counterion and polar environment on the structure and spectroscopic signatures of a hydrated hydroxyl anion based on DFT/M06-2X calculations in the polarizable cavity approximation reported in this work provide a tool to discriminate between the spectral signatures of the neutral, OH-(nH2O) B+, and anionic, OH-(nH2O), solvation clusters in aqueous solutions of alkali metal (B) hydroxides. These results demonstrate also that the precisions of the available experimental data and of the double harmonic approximation are insufficient to attribute the experimental spectral signatures to any specific cluster with the certain number of involved water molecules at least for 2 < n < 7. [ DOI ]
Cl center dot center dot center dot cl interactions in molecular crystals: Insights from the theoretical charge density analysis / M. V. Vener, A. V. Shishkina, A. A. Rykounov, V. G. Tsirelson // The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment & general theory. — 2013. — Vol. 117, no. 35. — P. 8459–8467. [ DOI ]
Noncovalent interactions in crystalline picolinic acid n-oxide: Insights from experimental and theoretical charge density analysis / A. V. Shishkina, V. V. Zhurov, A. I. Stash et al. // Crystal Growth and Design. — 2013. — Vol. 13, no. 2. — P. 816–828.
Strong is hydrogen bonding in ionic liquids? combined x-ray crystallographic, infrared/raman spectroscopic, and density functional theory study / S. A. Katsyuba, M. V. Vener, E. E. Zvereva et al. // Journal of Physical Chemistry B. — 2013. — Vol. 117. — P. 9094–9105. Hydrogen bonding in ionic liquids based on the 1-(2′-hydroxylethyl)-3-methylimidazolium cation ([C2OHmim]+) and various anions ([A]−) of differing H-bond acceptor strength, viz. hexafluorophosphate [PF6]−, tetrafluoroborate [BF4]−, bis-(trifluoromethanesulfonimide) [Tf2N]−, trifluoromethylsulfonate [OTf]−, and trifluoroacetate [TFA]−, was studied by a range of spectroscopic and computational techniques and, in the case of [C2OHmim][PF6], by single crystal X-ray diffraction. T. [ DOI ]
Intermolecular hydrogen bond energies in crystals evaluated using electron density properties: Dft computations with periodic boundary conditions / M. V. Vener, A. N. Egorova, V. G. Tsirelson, A. V. Churakov // Journal of Computational Chemistry. — 2012. — Vol. 33. — P. 2303–2309.
Intermolecular hydrogen bond energies in crystals evaluated using electron density properties: Dft computations with periodic boundary conditions / M. V. Vener, A. N. Egorova, A. V. Churakov, V. G. Tsirelson // Journal of Computational Chemistry. — 2012. — Vol. 33, no. 29. — P. 2303–2309. [ DOI ]
Qtaimc study of the x-h/h center dot center dot center dot o bond order indices (x = o, n, c) in molecular systems / E. V. Bartashevich, D. K. Nikulov, M. V. Vener, V. G. Tsirelson // Computational and Theoretical Chemistry. — 2011. — Vol. 973, no. 1-3. — P. 33–39. [ DOI ]
Dft study of h-bonds in the peptide secondary structures: The backbone-side-chain and polar side-chains interactions / M. V. Vener, A. N. Egorova, D. P. Fomin, V. G. Tsirelson // Journal of Molecular Structure. — 2010. — Vol. 972, no. 1-3. — P. 11–15. [ DOI ]
Vener M. V., Egorova A. N., Tsirelson V. G. Hydrogen bonds and o center dot center dot center dot o interactions in proton-ordered ices. dft computations with periodic boundary conditions // Chemical Physics Letters. — 2010. — Vol. 500, no. 4-6. — P. 272–276. [ DOI ]
A quantum-topological analysis of noncovalent interactions in secondary polyalanine structures / M. V. Vener, A. N. Egorova, D. P. Fomin, V. G. Tsirel'Son // Russian Journal of Physical Chemistry B. — 2009. — Vol. 3. — P. 541–547.
Hierarchy of the non-covalent interactions in the alanine-based secondary structures. dft study of the frequency shifts and electron-density features / M. V. Vener, A. N. Egorova, D. P. Fomin, V. G. Tsirelson // Journal of Physical Organic Chemistry. — 2009. — Vol. 22, no. 3. — P. 177–185. [ DOI ]
КВАНТОВО-ТОПОЛОГИЧЕСКИЙ АНАЛИЗ НЕКОВАЛЕНТНЫХ ВЗАИМОДЕЙСТВИЙ ВО ВТОРИЧНЫХ СТРУКТУРАХ ПОЛИАЛАНИНА / М. В. Венер, А. Н. Егорова, Д. П. Фомин, В. Г. Цирельсон // Химическая физика. — 2009. — Т. 28. — С. 3–10.
Dft study of proton dynamics in the potassium hydrogen maleate crystal: the infrared versus the inelastic neutron scattering spectra / M. V. Vener, A. V. Manaev, D. Hadzi, V. G. Tsirelson // ZEITSCHRIFT FUR PHYSIKALISCHE CHEMIE-INTERNATIONAL JOURNAL OF RESEARCH IN PHYSICAL CHEMISTRY & CHEMICAL PHYSICS. — 2008. — Vol. 222, no. 8-9. — P. 1349–1358. [ DOI ]
Molecular structure, barriers to internal rotation, and the enthalpy of formation of cumene hydroperoxide phcme2ooh: a dft study / A. N. Egorova, M. V. Vener, I. S. Zhukov et al. // Russian Chemical Bulletin. — 2008. — Vol. 57, no. 6. — P. 1179–1186.
Vener M. V., Manaev A. V., Tsirelson V. G. Proton dynamics in strong (short) intramolecular h-bond. dft study of the kh maleate crystal // The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment & general theory. — 2008. — Vol. 112, no. 51. — P. 13628–13632. [ DOI ]
КВАНТОВО-ТОПОЛОГИЧЕСКИЙ АНАЛИЗ КОРОТКИХ (СИЛЬНЫХ) ВОДОРОДНЫХ СВЯЗЕЙ В ТРЕХМЕРНЫХ ПЕРИОДИЧЕСКИХ КРИСТАЛЛАХ / М. В. Венер, А. В. Манаев, А. Н. Егорова, В. Г. Цирельсон // Химическая физика. — 2008. — Т. 27. — С. 19–32.
Структура, внутримолекулярные барьеры вращения и энтальпия образования гидропероксида кумола С6Н5С(СН3)2ООН по данным расчетов методами теории функционала плотности / А. Н. Егорова, М. В. Венер, И. С. Жуков и др. // Известия Академии наук. Серия химическая. — 2008. — С. 1157–1164.
Qtaim study of strong h-bonds with the o-h center dot center dot center dot a fragment (a = o, n) in three-dimensional periodical crystals / M. V. Vener, A. V. Manaev, A. N. Egorova, V. G. Tsirelson // The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment & general theory. — 2007. — Vol. 111, no. 6. — P. 1155–1162. [ DOI ]
Qtaim study of the closed-shell interactions in peptide secondary structures: A cluster treatment of oligo- and polyalanines / M. V. Vener, A. N. Egorova, D. P. Fomin, V. G. Tsirelson // Chemical Physics Letters. — 2007. — Vol. 440, no. 4-6. — P. 279–285. [ DOI ]
КОЛИЧЕСТВЕННЫЙ АНАЛИЗ Н-СВЯЗЕЙ В b-ПЕТЛЯХ НА ОСНОВЕ АЛАНИНА. ЧАСТОТНЫЕ СДВИГИ И ЭЛЕКТРОННЫЕ ХАРАКТЕРИСТИКИ КРИТИЧЕСКИХ ТОЧЕК / М. В. Венер, Д. П. Фомин, А. Н. Егорова, В. Г. Цирельсон // Успехи в химии и химической технологии. — 2007. — Т. 21. — С. 50–54.
Quantum-topological study of short h-bonds with the o..h..o fragment. molecular crystals versus isolated species / M. V. Vener, A. V. Manaev, A. N. Egorova, V. G. Tsirelson // III International Conference on H-bonding and Molecular interactions. Kyiv, Ukraine. Book of abstracts. — 2006. — P. 160.
СТРУКТУРА И ВНУТРИМОЛЕКУЛЯРНЫЕ БАРЬЕРЫ ВРАЩЕНИЯ 1-МЕТИЛ-1-ФЕНИЛ-ЭТИЛ КУМОЛ ГИДРОПЕРОКСИДА С6Н5С(СН3)2ООН ПО ДАННЫМ НЕЭМПИРИЧЕСКИХ РАСЧЕТОВ / А. Н. Егорова, М. В. Венер, И. С. Жуков и др. // Успехи в химии и химической технологии. — 2006. — Т. 20, № 3. — С. 55–59.
Heterogeneous catalytic synthesis and structure of 5,5a,10a,11-tetrahydro-10h-indeno[1,2-b]quinoline / V. PLESHAKOV, K. AMBACHEU, M. RYASHENTSEVA et al. // Russian Chemical Bulletin. — 1994. — Vol. 43, no. 6. — P. 1037–1040. Hydrogenation of 10H-indeno[1,2-b]quinoline in benzene in the presence of R(2)S(7) (250 degrees C, pH(2) = 140 atm, 4 h) gave 5,5a,10a,11-tetrahydro-10H-indeno[1,2-b]quinoline, the structure of which was established by mass-, IR, UV, C-13, and H-1 NMR spectra. The cis fusion of the indan and tetrahydroquinoline fragments, the axial orientation of the proton at C(5a), and the equatorial orientation of the proton at C(10a) were confirmed by molecular mechanics calculations using the PC MODEL program. [ DOI ]
Theoretical-study of homogeneous electron self-exchange in polar aromatic-molecules - the role of the reactant structure / M. VENER, N. IOFFE, A. CHEPRAKOV, V. MAIRANOVSKY // Journal of Electroanalytical Chemistry. — 1994. — Vol. 370, no. 1-2. — P. 33–39.
Structures of lithium salts of substituted 1-phenylpropynes: 13c nmr and mndo study / P. I. Dem’yanov, I. M. Styrkov, D. P. Krut’ko et al. // Journal of Organometallic Chemistry. — 1992. — Vol. 438, no. 3. — P. 265–288. 13C NMR spectroscopy has been used to study the structure of ambident carbanions in contact (CIP) and solvent-separated (SSIP) ion pairs of lithium salts of substituted 1-phenylpropynes. It was shown that the structures of carbanions in SSIP are close to the propargylic type, whereas, with the decrease in delocalizing ability of substituents at the propargylic centre, their structure shifts to the allenylic type, in fair agreement with theoretical predictions by the MNDO semi-empirical method. In CIP, the structures of carbanions are progressively changed from near-to-propargylic to allenylic with decrease of delocalizing ability of the substituents. [ DOI ]
Строение литиевых солей замещ.1-фенилпропинов: C(13)ЯМР и mndo-изучение / П. И. Демьянов, В. С. Петросян, И. М. Штырков и др. // Journal of Organometallic Chemistry. — 1992. — Т. 438. — С. 265.