共查询到20条相似文献,搜索用时 26 毫秒
1.
E. F. Kustov V. I. Nefedov A. V. Kalinin M. S. Karelina 《Russian Journal of Inorganic Chemistry》2008,53(7):1088-1097
A method has been developed for the determination of the structure and number of atoms in the shells of nanoparticles as a function of the arrangement of atoms at the symmetry elements of a symmetry group. The formulas for calculation of the number of particles of symmetry D 3d have been reported. It has been shown that the number of atoms in trigonal shells is determined by three structurally invariant numbers and the quantum number of the group order n. All possible nanostructures of symmetry D 3d have been classified: Cθ + 6z , z = 0, 1, 2, ..., where the basic shells are Cθ = C6, C8, and C14. A sum rule has been obtained for the coordination numbers of the shell sites located on symmetry axes. Trigonal nanoparticles are parent ones for obtaining (3,0), (6,0), and (9,0) nanotubes of trigonal type. The general formulas of these nanotubes with icosahedral, dodecahedral, and cubic caps are N8 + 12p , N20 + 24p , and N60 + 36p (p = 1, 2, ...), respectively. The graphical constructions of all classes of trigonal nanoparticles and nanotubes are reported. 相似文献
2.
The method of determination of the structure and the number of atoms in the shells of nanoparticles as a function of the arrangement of atoms at the symmetry elements of a symmetry group has been developed. The formulas for the calculation of the number of particles with symmetry group D 5d are reported. The number of particles in these shells is determined by three structurally invariant numbers and the “quantum number” of the group order n. The classification of all possible nanostructures with symmetry group D 5d is given: C θ+10z , z = 0, 1, 2, …, where the basic shells are C θ = C 2, C 10, C 12. The sum rule has been obtained for the coordination numbers of shell sites located at symmetry axes. Pentagonal axial nanoparticles are shown to be the initial shells for obtaining (5,5) and (10,10) armchair nanotubes or (5,0) and (10,0) zigzag nanotubes. The general formula of these nanotubes closed with icosahedral and dodecahedral caps is N 20+10p , N 60+10p (p = 1, 2, …). The graphical constructions of all classes of nanoparticles and nanotubes of the pentagonal axial type are reported. 相似文献
3.
Debdas Mandal Rakesh Ganguly Pabitra Baran Chatterjee Akira Endo Timothy J. R. Weakley Muktimoy Chaudhury 《Structural chemistry》2007,18(2):187-193
Two cis-dioxomolybdenum(VI) complexes [MoO2L] (L: L 1, 2 and L: L 2, 3) in a phenol-based sterically encumbered N2O2 ligand environment have been synthesized, and their crystallographic characterizations are reported. The orange crystals of 2 are monoclinic, space group P21/a with unit cell dimensions as a=16.2407(17) Å, b=7.2857(8) Å, c=18.400(2) Å, β=98.002(9)°, Z=4, and d cal=1.486 g cm?3. The light orange crystals of 3, however, are orthorhombic, space group, Pbcn, with unit cell dimensions a=8.3110(12) Å, b=12.637(3) Å, c=34.673(5) Å, Z=4, and d cal=1.187 g cm?3. The structures were refined by a full-matrix least-squares procedure on F 2 to a final R=0.046 (0.055 for 3) using 4944 (3677) all independent data. In both the cases, the Mo atom exists in a distorted octahedral geometry defined by a N2O4 donor set, which features a cis-Mo(–O)2 and a trans-Mo(OPh)2 arrangement. Compound 2 undergoes a quasireversible one-electron reduction at ?1.3 V vs Ag/AgCl reference due to MoVIO2/MoVO2 electron transfer and thus providing a rare example of steric solution to the comproportionation–dimerization problem encountered frequently in the development of valid biomimetic models for the active sites of oxomolybdenum enzymes. 相似文献
4.
The reaction of N-methyl-N-trimethylsilylacetamide with silanes ClCH2SiR1R2Cl (R1, R2 = H, Me; H, Ph; Ph2) leads to the formation of (O→Si) chelate compounds with pentacoordinate silicon: N-[chloro(methyl)-silyl]methyl-, N-[chloro(phenyl)silyl]methyl-, and N-[chloro(diphenyl)silyl]methyl-N-methylacetamides. From the data of multinuclear NMR spectroscopy, the intermediates of the reaction of N-methyl-N-trimethylsilylacetamide with ClCH2SiPhHCl and ClCH2SiPh2Cl are stable in CDCl3 solution at room temperature during several days and slowly rearrange to the final (O–Si) chelate compounds. 相似文献
5.
G. S. Kuanysheva K. U. Dzhamansarieva G. Zh. Sdikova 《Russian Journal of Inorganic Chemistry》2007,52(9):1359-1362
The mean atomic Gibbs energies of formation of (Δ f ? at 0 ) of s-, p-, and d-element diphosphates have been calculated using ion increments of the Gibbs energy (Δ f G 0). The diphosphate hydrolysis kinetics is considered, and a correlation between the Δ f ? at 0 values and the hydrolysis rate constants is presented. 相似文献
6.
A. N. Chekhlov 《Journal of Structural Chemistry》2005,46(1):182-184
The crystal and molecular structure of tris(m-chlorophenyl)phosphine selenide, C18H12Cl3PSe (I), was investigated by X-ray diffraction (XRD) analysis. The trigonal rhombohedral structure of I (space group \(R\overline 3 c\), a = 14.110(2) Å, c = 32.360(4) Å, Z = 12) was solved by direct methods and refined by least squares in an anisotropic approximation (R = 0.029) for 1319 averaged measured reflections (CAD-4 automatic diffractometer, λCuKα). 相似文献
7.
Properties of frontier orbitals and low-energy electronic transitions in a d 0-organometallic complex have been studied by TDDFT and DFT methods using B3LYP hybrid functional and 3-21G*, 6-31G**, SDD, CEP-121G, and DGDZVP basis sets. It has been shown that the electronic transition between frontier orbitals in the excitation and absorption spectra is associated with charge transfer mainly from π-type ligands to a central metal d 0-ion. The good agreement of the data (the shape and band position of the spectra of electronic absorption and excitation, energy of electronic transitions, and strength of the harmonic oscillator) of quantum-chemical and photophysical studies is demonstrated. 相似文献
8.
Marco Bortoluzzi Dario Battistel Gabriele Albertin Salvatore Daniele Francesco Enrichi Riccardo Rumonato 《Chemical Papers》2016,70(1):43-52
1,10-Phenanthroline-5,6-dione (Phd) complexes of group 3 and lanthanide elements having formulae Ln(hfac)3(Phd) (Ln = Y, Eu, Yb; hfac = hexafluoroacetylacetonate) were synthesised and characterised. Complexes of d-block elements of the type [MCl(Phd)(p-cymene)]+ (M = Ru, Os) were also prepared. In all these species, coordination of the polydentate ligand occurs by the N-donor moieties, as indicated by DFT calculations. The novel compounds were tested, together with fac-ReBr(Phd)(CO)3, as precursors for the preparation of heterobimetallic d/f derivatives. The reaction of the rhenium complex with yttrium or lanthanide anhydrous triflate salts led to the formation of the complexes ReBr(CO)3(N,N′-Phd-O,O′)Ln(OTf)3(THF) (Ln = Y, Eu, Yb), where the trivalent ions interacted with the quinonoid moiety. The redox properties of the rhenium centre were strongly affected by the coordination of Ln(OTf)3, as observed by comparing the cyclic voltammetry measurements carried out on fac-ReBr(Phd)(CO)3 and on ReBr(CO)3(N,N′-Phd-O,O′)Y(OTf)3. 相似文献
9.
Dhiraj Brahman Amarjit Kamath Dipu Kumar Mishra Biswajit Sinha 《Journal of solution chemistry》2017,46(3):589-612
The densities, viscosities and refractive indices of N,N /-ethylene-bis(salicylideneiminato)-diaquochromium(III) chloride, [Cr(salen)(H2O)2]Cl, in aqueous dimethylsulfoxide (DMSO) with different mass fractions (w 2 = 0.20, 0.40, 0.60, 0.80 and 1.00) of DMSO were determined at 298.15, 308.15 and 318.15 K under atmospheric pressure. From measured densities, viscosities and refractive indices the apparent molar volumes (V φ ), standard partial molar volume (V φ 0 ), the slope (S V * ), standard isobaric partial molar expansibility (φ E 0 ) and its temperature dependence (?φ E 0 /?T) p , the viscosity B-coefficient, its temperature dependence (?B/?T), solvation number (S n ) and apparent molar refractivity (R D φ ), etc., were calculated and discussed on the basis of ion–ion and ion–solvent interactions. These results revealed that the solutions are characterized by ion–solvent interactions rather than by ion–ion interactions and the complex behaves as a long range structure maker. Thermodynamics of viscous flow was discussed in terms of transition state theory. 相似文献
10.
N. V. Nastapova A. S. Stepanov V. V. Yanilkin V. A. Burilov V. V. Skripacheva A. R. Mustafina S. E. Solov’eva A. I. Konovalov 《Russian Journal of Electrochemistry》2009,45(7):783-794
The electrochemical properties of n-sulfonatothiacalyx[4]arene (H4XNa4) complexes with [Co(dipy)3]3+ and Fe3+ ions were studied by means of cyclic voltammetry in aqueous solution at pH 2.5. The observed single-electron reduction of [Co(dipy)3]3+ bound extraspherically to the upper rim and Fe3+ ion bound intraspherically to the lower rim of n-sulfonatothiacalyx[4]arene in binary [Co(dipy)3]3+ · H3X5?, H3X5? · Fe3+, and ternary [Co(dipy)3]3+ · H3X5? · Fe3+ heterometal complexes was more difficult than in the free state. The reversible single-electron transfer to the metal ion results in lower binding energy ([Co(dipy)3]3+, ΔΔG 0 = 3.9 kJ/mol) or in full fast dissociation of the complex (Fe3+). The ternary complex in the solution forms the aggregates, in which inner encapsulated Fe(III) and Co(III) ions are not reduced on the electrode. Their quantitative reduction takes place by the relay mechanism of intra- and intermolecular electron transfer through electrochemically generated [Co(dipy)3]2+ outer ions. 相似文献
11.
G. S. Kuanysheva K. U. Dzhamansarieva G. Zh. Sdikova 《Russian Journal of Inorganic Chemistry》2007,52(9):1363-1364
The hydrolysis kinetics of the anion in 3d-element cyclotetraphosphates is considered. The thermodynamic functions of formation (Δ f H 0, Δ f G 0, and Δ f ? at 0 ) of the cyclotetraphosphates are calculated using the ion increment method. A linear correlation is established between and log K Δ f ? at 0 for these compounds. 相似文献
12.
A. V. Soldatov A. N. Kravtsova L. N. Mazalov S. V. Trubina N. A. Kryuchkova G. B. Sukharina 《Journal of Structural Chemistry》2007,48(6):1061-1065
The NiK edge X-ray absorption near edge spectra (XANES) of the Ni(EtOCS2)2 complex were measured. The theoretical NiK edge XANES spectra were calculated by the total multiple scattering and finite difference methods; the potential was calculated with a muffin-tin approximation and without it. It is shown that inclusion of the non-muffin-tin effects is important for modeling the NiK XANES spectrum for the Ni(EtOCS2)2 complex; good agreement with experiment was achieved only in the calculations with the total potential (without the muffin-tin approximation for the shape of the potential). 相似文献
13.
Yu. Yu. Rusakov L. B. Krivdin E. Yu. Shmidt A. M. Vasil’tsov A. I. Mikhaleva B. A. Trofimov 《Russian Journal of Organic Chemistry》2007,43(6):880-887
Conformational analysis of ten N-vinylpyrroles was performed on the basis of experimental 13C-1H and 13C-13C coupling constants and those calculated by high-level quantum-chemical methods, and principal relations between J CC and J CH values and stereochemical structure of these compounds were revealed. 相似文献
14.
I. I. Zakharov V. F. Anufrienko O. I. Zakharova S. A. Yashnik Z. R. Ismaguilov 《Journal of Structural Chemistry》2005,46(2):213-219
A comparative quantum chemical analysis has been made for the most stable dimer of nitrogen oxide with the structure cis-ONNO in a singlet state 1A1 by ab initio method of SCF MO LCAO, allowing for electron correlation according to Meller-Plesset perturbation theory of the second order (MP2), and density functional technique (DFT). The computations by MP2 method show anion-radical (ONNO)? to have a strong bond between nitrogen atoms (N-N 1.44 Å) in contrast to molecular weakly bound cis-dimer with equilibrium distance N-N 2.23 Å. Molecular orbital structure of the dimer and its anions was examined that made it possible to suggest a reason of preferable stabilization of nitrogen oxide dimer in the cis-form. Calculated high affinity to electron (Ea = ?1.55-?1.69 eV) for the molecular dimer ONNO (1A1) explains an intense strengthening of N-N bond in anion-radical and confirms the experimental data on a possibility of surface anion-π-radical formation on electron donor centers. The DFT computations indicate that this technique poorly reproduces the experimental geometry and electron structure of the cis-dimer ONNO having predicted a triplet ground state with the equilibrium distance N-N ≈2 Å instead of a singlet one with N-N 2.26 Å. The comparison between MP2 and DFT calculations for complex dimer ONNO with copper cation reveals the energy state of the complex (Cu-O2N2)+ corresponding to stabilization of anion-π-radical (N2O2)? {term-3A2, Cu(d)9-(ONNO)?1} to be highly overestimated by DFT. 相似文献
15.
Modern quantum-chemical and photophysical methods have been used to study the structure of the frontier molecular orbitals and the nature of ligand-to-metal charge transfer (LMCT) transitions of structurally complex d 0-metallocenes. It has been shown that such metal complexes with carboranyl ligands have emissive LMCT states with preferential charge transfer from aromatic π-ligands to the metal and a large electric dipole moment. The electronic excitation and absorption spectra were simulated for the first time, and dipole moments of metal complexes containing metal–carbon σ- and π-bonds were estimated, which is of fundamental importance for the development of molecular photonics. 相似文献
16.
Tautomers of N-allyl- and N-propargyl-substituted trifluoromethanesulfonimides (CF3SO2)2NR (R = CH2CH=CH2, Z/E-CH=CHMe, CH2C≡CH, CH=CH=CH2, C≡CCH2) were calculated by the DFT (B3LYP, wB97XD, PBE1PBE), MP2, and CBS-QB3 methods. The results were compared with the theoretical data for the corresponding amines and amides NHRR1 (R1 = H, CF3SO2). It was shown that there is no conjugation between the nitrogen atom and C=C bond and that conjugation exists with the C≡C bond with electron density displacement toward the nitrogen atom. The calculations of anions derived from N-allyl- and N-propargyl-trifluoromethanesulfonimides revealed the possibility of their rearrangement with elimination of trifluoromethanesulfinate anion and formation of its H-complex with N-(prop-2-en-1-ylidene)trifluoromethanesulfonamide or N-(prop-2-yn-1-ylidene)trifluoromethanesulfonamide. 相似文献
17.
A. O. Kharaneko 《Russian Journal of Organic Chemistry》2017,53(5):738-745
A strategy was developed for the synthesis of 7,8,9-trimethyl-1-phenyl-3H-pyrrolo[2,1-d][1,2,5]-triazepin-4(5H)-one, reactions of its functionalization at the С4 atom and aza rings fusion at the С4?N3 bond were explored. The formation mechanism of the pyrrolo-1,2,5-triazepinone scaffold was suggested. 相似文献
18.
P. A. Storozhenko Z. V. Belyakova O. A. Starikova V. M. Nosova T. I. Shulyat’eva A. S. Frenkel’ M. V. Pecherskii 《Russian Journal of General Chemistry》2008,78(5):892-897
N-Metallation of bromoanilines with ethylmagnesium bromide followed by a reaction with trimethylchlorosilane provided N-mono and N-bis(trimethylsilyl)bromoanilines depending on the structure of substrate. The metallation of bissilylated bromoanilines with butyllithium permitted the introduction of a trimethylsilyl substituent in the aromatic ring. Previously unknown 2-bromo-N,N-bis(trimethylsilyl)aniline, 2,6-dibromo-N-trimethylsilylaniline, 2,6-dibromo-N,N-bis(trimethylsilyl)aniline, 2-bromo-6-trimethylsilylaniline, 2-bromo-6-trimethylsilyl-N,N-bis(trimethylsilyl)aniline, 2-bromo-6-trimethylsilyl-N-trimethylsilylaniline, 2,4,6-tribromo-N-trimethylsilylaniline, and 2,4,6-tribromo-N,N-bis(trimethylsilyl)aniline were prepared. The structures of the compounds obtained were established by the chromato-mass spectrometry and 1H, 13C, and 29Si NMR spectroscopy. 相似文献
19.
I. B. Rozentsveig B. A. Shainyan E. V. Kondrashov E. V. Rudyakova G. N. Rozentsveig K. A. Chernyshev G. G. Levkovskaya 《Russian Journal of Organic Chemistry》2008,44(9):1332-1337
N-(2,2,2-Trichloroethylidene)arenesulfonamides react with 1H-pyrrole and 1-methyl-1H-pyrrole to give the corresponding N-[2,2,2-trichloro-1-(1H-pyrrol-2-yl)ethyl]arenesulfonamides. The reaction of N-(2,2,2-trichloroethylidene)trifluoromethanesulfonamide with pyrrole leads to a mixture of 2-mono-and 2,5-disubstituted pyrroles, whereas in the reaction with 1-methyl-1H-pyrrole only the 2-substituted compound is formed. N-(2,2-Dichloro-2-phenylethylidene)-4-methylbenzenesulfonamide reacts with 1H-pyrrole to form N-[2,2-dichloro-2-phenyl-1-(1H-pyrrol-2-yl)ethyl]-4-methylbenzenesulfonamide, and its reaction with 1-methyl-1H-pyrrole gives a mixture of 2-and 3-monosubstituted derivatives. The results of quantum-chemical calculations of the initial reactants and products indicate that the process is orbital-controlled. A good agreement is observed between the experimental data and theoretical conclusions concerning the dependence of the reaction regioselectivity on the nature of substituents in the electrophile molecule. 相似文献
20.
G. V. Novikov L. N. Kulikova O. Yu. Bogdanova G. I. Sychkova O. M. Dara I. G. Lugovskaya 《Russian Journal of Inorganic Chemistry》2009,54(2):180-190
Layered compounds based on hydrous manganese dioxide (hereafter, Mn-phases) saturated with s-metal (Ba2+), p-metal (Pb2+), and d-metal (Mn2+, Co2+, Ni2+, Cu2+, Zn2+, and Cd2+) cations, analogues of manganese minerals of oceanic ferromanganese formations (vernadite, birnessite, buserite-I, and asbolan), were prepared at 4–6°C. All Mn-phases have poorly ordered structures. The sorption properties of phase compounds were studied in relation to alkali-metal (Na+ and K+) and other s-, p-, and d-metal cations. The exchange capacities of Mn-phases for alkali cations are very low, within 0.02–0.10 mg-equiv/g; for the other cations, the exchange capacities are 0.13–4.20 mg-equiv/g. The sorption of divalent metal cations depends on the phase and chemical composition of the Mn-phase. 相似文献