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1.
The existence of a hydrogen bond in which a methyl group of the (MeOH)2H+ ion acts as a proton donor is examined. The fundamental vibration frequencies of this ion were calculated for different numbers
and strengths of CH…O bonds. The atomic charges in neutral ((MeOH)
n
,n=1–4) and protonated ((MeOH)
m
H+,m=2–6) associates of methanol molecules were also calculated. The experimentally observed decrease in the v(CH) vibration frequencies
of the (MeOH)2H+ ion to 2890 cm−1 and 2760 cm−1 is attributable to the fact that each methyl group of the ion is involved in formation of two CH…O bonds with strength of
−12.5 kJ mol−1. The proton-donating ability of the CH bond depends on the charge on its H atom; however, it does not correlate with the
dipole moment of this bond.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 306–312, February, 1999. 相似文献
2.
Yu. A. Borisov Yu. A. Zolotarev E. V. Laskatelev N. F. Myasoedov 《Russian Chemical Bulletin》1998,47(8):1442-1445
Ab initio calculations of molecular and electronic structures of neutral molecules and protonated forms of methionine and its derivatives
in the gaseous phase were carried out by the Hartree-Fock method using the 6–31G* basis set with full geometry optimization. Proton affinities of methionine (1), methionine sulfoxide (2), and methionine
sulfone (3) were calculated for different modes of coordination of the proton. The results of calculations demonstrated that
in protonated forms of 1 and 3, bonding between the proton and the N atom is most favorable, while in protonated form of 2,
bonding between the proton and the O atom of the SO group is most favorable. The proton affinities of the amino acids are
as follows: 223.2 (1), 241.2 (2), and 221.5 (3) kcal mol−1,i.e., methionine sulfoxide 2 exhibits the highest proton affinity in the series of the amino acids under consideration.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1487–1490, August, 1998. 相似文献
3.
V. A. Afanasieva L. A. Glinskaya R. F. Klevtsova I. V. Mironov 《Journal of Structural Chemistry》2005,46(5):876-882
Protonation equilibrium has been studied for the acyclic gold(III) tetraaza metallocomplex [AuB]2+ [B = N, N′-bis(2-aminoethyl)-2,4-pentanediiminato(1−)] in aqueous solution. The synthetic procedure is described. The crystal
and molecular structure of the protonated form of the [AuHB](H5O2)(ClO4)4 complex has been determined. Monoclinic crystals with unit cell dimensions a = 11.964(2) Å, b = 13.789(3) Å, c = 15.496(3) Å, β = 109.00(3)°, V = 2417.1(8) Å3, Z = 4, ρcalc = 2.243 g/cm3, space group P21/n. The structure is built of nearly planar [Au(C9H20N4)]3+ complex cations, (H5O2)+ cations, and [ClO4]− anions. The gold atom coordinates four nitrogen atoms of the ligand, forming a square plane. The six-membered chelate ring
of the ligand is protonated at the central β-carbon atom and contains imine C=N bonds. The oxygen atoms of the perchlorate
ions are hydrogen bonded to the (H5O2)+ dihydroxonium ion and to the nitrogen atoms of the NH2 groups of the [AuHB]3+ cation.
Original Russian Text Copyright ? 2005 by V. A. Afanasieva, L. A. Glinskaya, R. F. Klevtsova, and I. V. Mironov
__________
Translated from Zhurnal Strukturnoi Khimii, Vol. 46, No. 5, pp. 909–915, September–October, 2005. 相似文献
4.
Henryk Wincel 《Journal of the American Society for Mass Spectrometry》2009,20(10):1900-1905
Thermochemical data, ΔH
n
o
, ΔS
n
o
, and ΔG
n
o
, for the hydration of protonated nucleic acid bases and protonated nucleosides have been experimentally studied by equilibrium
measurements using an electrospray high-pressure mass spectrometer equipped with a pulsed ion-beam reaction chamber. For protonated
nucleobases the hydration enthalpies were found to be similar for all studied systems and varied between 12.4–13.1 kcal/mol
for the first and 11.2–11.5 kcal/mol for the second water molecule. While for protonated nucleosides the water binding enthalpies
(11.7–13.3 kcal/mol) are very close to those for protonated nucleobases, the entropy values are “more negative.” The structural
and energetic aspects of hydrated ions are discussed in conjunction with the available theoretical data. 相似文献
5.
E. G. Tarakanova 《Journal of Structural Chemistry》1995,36(2):338-342
The calculated anharmonic frequencies and intensities of simultaneous vibrational transitions in CO2−H2O and (CO2)2−H2O hydrogen-bonded complexes are compared with known experimental data. Hydrogen-bonded complexes form in liquid CO2 solutions of water under normal conditions, unlike the gas phase in which the CO2 and H2O molecules are coupled by van der Waals bonds. The majority of these complexes are 2∶1 complexes.
N. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 2, pp. 375–379, March–April, 1995.
Translated from E. Taskaeva 相似文献
6.
Electrochemistry of hydrofullerene C60H36 was studied by cyclic voltammetry in THF and CH2Cl2 in the −47–14 °C temperature range. Hydrofullerene undergoes reversible one-electron reduction to form a radical anion in
THF (E
0=−3.18 V (Fc0/Fc+), Fc=ferrocene) and irreversible one-electron oxidation in CH2Cl2 (E
p
a
=1.22 V (Fc0/Fc+)). The reduction potential was used to estimate electron affinity of hydrofullerene as EA=−0.33 eV. It was suggested that
C60H36 is an isomer withT-symmetry in which 12 double bonds form four isolated benzenoid rings located in vertices of an imaginary inscribed tetrahedron
on the molecular surface. For hydrofullerene, the “electrochemical gap” is an analog of the energy gap (HOMO−LUMO), equal
to (E
Ox−E
Red)=4.4 V, and indicates that C60H36 is a sufficiently “hard” molecule with a low reactivity in redox reactions.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2083–2087, November, 1999. 相似文献
7.
L. S. Khaikin O. E. Grikina V. A. Sipachev A. A. Granovsky V. S. Nikitin 《Russian Chemical Bulletin》2000,49(4):620-630
The geometry and force fields of the bis(trimethylstannyl)acetylene molecule (a conformer withD
3d
symmetry corresponding to a minimum of the total energy of the molecule) were calculated by the RHF and MP2(fc) methods.
The effective core potential in SBK form with the optimized 31G* valence basis set was employed in the case of Sn atoms. The 6–31G** and 6–311G** basis sets were used for carbon and hydrogen atoms. Vibrational spectra of the light and perdeuterated isotopomers of bis(trimethylstannyl)acetylene
were interpreted using the procedure of scaling the quantum-chemical force fields.
For Part 5, see Ref. 1.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 616–626, April, 2000. 相似文献
8.
R. G. Bulgakov L. I. Sharapova G. L. Sharipov G. G. Bikbaeva 《Russian Chemical Bulletin》1999,48(4):790-793
The mechanism of oxidation of Cp2Fe by ozone in CCl4 was studied by chemiluminescence (CL), photoluminescence, IR, UV, and NMR spectral techniques, Ozone attacks Cp2Fe at the Fe−C and C=C bonds to form peroxides CpOOFe, CpFeOOH, triplet (3 nπ*) ketones (CL emitters), and organic acids.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 794–797, April, 1999. 相似文献
9.
S. F. Ledenkov V. N. Vandyshev A. S. Molchanov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2012,86(6):959-964
Enthalpies of the interaction of protonated dopamine with a hydroxide ion in water-ethanol mixtures in the concentration range
of 0–0.8 EtOH mole fractions are measured calorimetrically. The neutralization process of dopamine hydrochloride is shown
to occur endothermally in solvents with an ethanol concentration of ≥0.5 mole fractions. Standard thermodynamic characteristics
(Δr
H
○, Δr
G
○, and Δr
S
○) of the first-step acid dissociation of dopamine hydrochloride in solutions are calculated with regard to the autoprotolysis
enthalpy of binary solvents. It is found that dissociation enthalpies vary within 9.1–64.8 kJ/mol, depending on the water-ethanol
solvent composition. 相似文献
10.
A. V. Glushkov V. A. Efimov E. D. Gopchenko S. V. Ambrosov V. I. Polishchuk I. M. Shpinareva 《Journal of Structural Chemistry》1998,39(4):480-483
Interatomic potentials are calculated for the systems inert gas ion in the ground state-inert gas atom Ne+, Xe+ -Ne, Ar, Kr, Xe, Fr. The calculation is performed by the effective pseudopotential method using the new form of the polarization
interaction potential obtained by calculating the most important polarization diagrams of perturbation theory in the Thomas-Fermi
approximation. The quasimolecular states of these van der Waals systems are calculated to refine the available data; some
data are obtained for the first time.
Translated fromZhumal Strukturnoi Khimii, Vol. 39, No. 4, pp. 591–595, July–August, 1998. 相似文献
11.
R. Bishop D. C. Craig I. G. Dance M. L. Scudder A. T. Ung 《Journal of Structural Chemistry》1999,40(5):663-671
Crystallization of 2,7-dimethyltricyclo[43.1.13,8]undecane-syn-2,syn-7-diol 2 from acetonitrile or dichloro-methane yields the compounds (2)4-(guest) in space group 141/acd which are further examples of the ellipsoidal clathrate structure. Both enantiomers of 2 are linked through (O-H)4 cycles of hydrogen bonds to form a three-dimensional sublattice. Two inversion related sublattices interpenetrate thereby
generating a superlattice with guest-occupied voids situated between the two individual sublattices. The two X-ray structures
are compared and contrasted with that of Powell’s (hydroquinone)3 (SO2) clathrate compound.
Translated fromZhurnal Strukturnoi Khimii, Vol. 40, No. 5, pp. 822–831, September–October, 1999. 相似文献
12.
G. F. Khudorozhko É. A. Kravtsova L. N. Mazalov V. E. Fedorov L. G. Bulusheva I. P. Asanov G. K. Parygina Yu. V. Mironov 《Journal of Structural Chemistry》1996,37(5):767-772
The electronic structure of cubanocluster compounds of the series Re4−xMoxS4Te4 was studied by X-ray emission and X-ray photoelectron spectroscopy. The electronic structure of the (Re4S4)8+ cluster was calculated by the EHT method. It is shown that replacement of rhenium atoms by molybdenum atoms leads to changes
both in the chemical bonds of the Re4S4 cubanocluster fragment and in the bond of the latter with the Te4 fragment.
Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 5, pp. 901–906, September–October, 1996.
Translated by L. Smolina 相似文献
13.
Paizs B Bythell BJ Maître P 《Journal of the American Society for Mass Spectrometry》2012,23(4):664-675
The structure of the a
4
ion from protonated YGGFL was studied in a quadrupole ion trap mass spectrometer by ‘action’ infrared spectroscopy in the
1000–2000 cm–1 (‘fingerprint’) range using the CLIO Free Electron Laser. The potential energy surface (PES) of this ion was characterized
by detailed molecular dynamics scans and density functional theory calculations exploring a large number of isomers and protonation
sites. IR and theory indicate the a
4
ion population is primarily populated by the rearranged, linear structure proposed recently (Bythell et al., J. Am. Chem.
Soc. 2010, 132, 14766). This structure contains an imine group at the N- terminus and an amide group –CO–NH2 at the C-terminus. Our data also indicate that the originally proposed N-terminally protonated linear structure and macrocyclic
structures (Polfer et al., J. Am. Chem. Soc. 2007, 129, 5887) are also present as minor populations. The clear differences between the present and previous IR spectra are
discussed in detail. This mixture of gas-phase structures is also in agreement with the ion mobility spectrum published by
Clemmer and co-workers recently (J. Phys. Chem. A
2008, 112, 1286). Additionally, the calculated cross-sections for the rearranged structures indicate these correspond to the most abundant
(and previously unassigned) feature in Clemmer’s work. 相似文献
14.
M. R. Baklanov A. A. Karpushin K. P. Moginikov A. N. Sorokin 《Journal of Structural Chemistry》1996,37(1):11-17
We used the AM1 quantum chemical and cluster models to study the mechanism of formation of a SiF2-like layer and dissociation of the Si−Si bond during the interaction of atomic fluorine with the (111) surface of silicon.
It is shown that the negatively charged (Si3−Si−F2)− complex with the five-coordinated centered silicon atom plays an important part in these processes. The above complex participates
in the interaction of atomic fluorine with silicon to form a SiF2-like layer and break the subsurface Si−Si bonds without penetration of fluorine atoms into the subsurface silicon layers.
Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 1, pp. 14–21, January–February, 1996.
Translated by I. Izvekova 相似文献
15.
To explore the interactions between ubiquinones and oxygen in living organisms, the thermodynamics of a series of electron
and hydrogen transfer reactions between semiquinone radicals, as well as their corresponding protonated forms, and oxygen,
singlet or triplet, were studied using the hybrid Hartree–Fock–density functional theory method Becke's three parameter hybrid
method with the Lee, Yang, and Parr correlation functional. Effects of the solvent and of the isoprenyl tail on the electron
and hydrogen transfer reactions were also investigated. It is found that semiquinone radicals (semiquinone anion radicals
or protonated semiquinone radicals) cannot react with triplet oxygen to form the superoxide anion radical O2
−. In contrast, neutral quinones can scavenge O2
− efficiently. In the gas phase, only protonated semiquinone radicals can react spontaneously with singlet oxygen to produce
peroxyl radical (HO2). However, both semiquinone anion radicals and protonated semiquinone radicals can react with singlet oxygen to produce harmful
oxygen radicals (O2
−
a
l
l
b
u
l
l
and HO2, respectively) in aqueous and protein environments. The free-energy changes of the corresponding reactions obtained for different
ubiquinone systems are very similar. It clearly shows that the isoprenyl tail does not influence the electron and hydrogen
transfer reactions between semiquinone radicals and oxygen significantly. Results of electron affinities, vertical ionization
potentials, and proton affinities also show that the isoprenyl tail has no substantial effect on the electronic properties
of ubiquinones.
Received: 3 July 2000 / Accepted: 6 September 2000 / Published online: 21 December 2000 相似文献
16.
E. S. Shubina N. V. Belkova E. V. Bakhmutova L. N. Saitkulova A. V. Ionidis L. M. Epstein 《Russian Chemical Bulletin》1998,47(5):817-822
The results of experimental and theoretical studies of intermolecular MH...HX and BH...HX hydrogen bonds with the hydride
hydrogen atom acting as a proton accepting site are analyzed. Spectral (IR and NMR) criteria for their formation are presented.
The spectral, structural, and thermodynamic characteristics of these unusual hydrogen bonds obey the regularities found for
classical hydrogen bonds. It was shown that the MH...HX bonds participate in the proton transfer with the formation of nonclassical
cationic hydrides and the |M(η2-H2|+ hydrogen bonds are formed in low-polarity media. Problems arising in this new line of investigations are discussed.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 846–851, May, 1998. 相似文献
17.
This paper deals with the mechanisms of localization of Franck-Condon vibronic coupling of πσ*- or πlπ*-orbital type in a few vibrational modes, (LVM) in excited electronic states of polyatomic molecules. The analysis of vibronic
coupling uses highly symmetric basis sets (for representing MO structures and normal coordinates ξR) as well as simplified models that relate the shift ΔR of the electron potential minima along the normal coordinates to the MO structure and to ξR in the form of analytical expressions. The modes that are active in LVM are determined from the experimental luminescence
spectra. These ideas about approximately high local symmetry of vibronic coupling in benzene fragments as well as the estimates
of ΔR depending on variations in the MO structure explain the experimental results.
L. Ya. Karpov Physicochemical Scientific Research Institute. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 2, pp. 286–291, March–April, 1995.
Translated by L. Smolina 相似文献
18.
N. I. Medvedeva V. P. Zhukov D. L. Novikov V. A. Gubanov 《Journal of Structural Chemistry》1996,37(1):41-50
The band structure of the fluorite-type δ-Bi2O3 was calculated by the linear LMTO methods in the approximation of overlapping atomic spheres using the basis set of orthogonal
orbitals (LMTO-ASA) and by the full-potential LMTO method (LMTO-FP) for two vacancy orientations over a wide range of oxygen
concentrations. The calculated parameters of chemical bonds—the binding energy Ebin and the pressure of the electron-nuclear system—show that the most stable compound is that with two vacancies per unit cell,
oriented predominantly along the (111) direction. The hybrid Bi−O bonds are weak, and mostly the Bi−Bi bonds are responsible
for the structural stabilization of δ-Bi2O3. The mechanism of the formation of a semiconductor gap in the band structure of δ-Bi2O3 is discussed.
Institute of Solid State Chemistry, Ural Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 1, pp. 48–58, January–February, 1996.
Translated by I. Izvekova 相似文献
19.
The electronic structures of amidine CH3C(NH)NH2 and its complex [Pt(NH3)5{CH3C(NH)NH2}]4+ are studied by the semiempirical CNDO method and by the ab initio Hartree-Fock-Roothaan method using the effective core potential
for the platinum atom by the GAUSSIAN-92 program. It is shown that in free amidine the protonation of the NH group is energetically
more profitable than the protonation of the NH2 group. Formation of the amidine-platinum(IV) ion complex is accompanied by a considerable redistribution of electron density
in amidine atoms and bonds. In the above complex, the amidine NH2 group exhibits enhanced protophilic properties.
St. Petersburg State Technological Institute (Technical University). Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 2, pp. 220–224, March–April, 1996.
Translated by I. Izvekova 相似文献
20.
L. S. Khaikin O. E. Grikina B. I. Zhilinskii E. A. Zhilinskaya E. G. Baskir R. V. Nepomnyashchii O. A. Fomicheva M. V. Proskurnina 《Russian Chemical Bulletin》1998,47(9):1653-1665
The equilibrium geometric parameters and structures of transition states of internal rotation for the molecules of methyldicyanophospine
MeP(CN)2 and its isocyano analog MeP(NC)2 were calculated by the RHF and MP2 methods with the 6–31G* and 6–31G** basis sets. At the MP2 level, the total energy of cyanide is −35 kcal mol−1 lower than that of isocyanide and the barriers to internal rotation of methyl group for MeP(CN)2 and MeP(NC)2 are 2.2 and 2.7 kcal mol−1, respectively. For both molecules, the one-dimensionalab initio potential functions of internal rotation approximated by a truncated Fourier series were used to determine the frequencies
of torsional transitions by solving direct vibrational problems for a non-rigid model. The Raman spectrum of crystalline MeP(CN)2 was recorded in the range 3500–50 cm−1. The vibrational spectra of this compound were interpreted by scalingab initio force fields calculated by the RHF and MP2 method. The vibrational spectrum of methyldiisocyanophosphine was predicted with
the use of the obtained scale factors.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1703–1714, September, 1998. 相似文献