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1.
The tetranuclear Cu4OBrnCl(6-n)L4 complexes, where L = 3-methylpyridine (3-Mepy), 4-methylpyridine (4-Mepy) and n=0–6 with trigonal bipyramidal coordination of copper(II) were prepared and their infrared and electronic absorption spectra
as well as cyclic voltammograms in nitromethane solutions were measured. The polyhedra in Cu4OBrnCl(6−n) (3-Mepy)4 molecules are less distorted comparing with those of 4-Mepy analogues as indicated by infrared Cu4O absorptions, far infrared Cu—Br, Cu—Cl, and Cu—N absorptions, d—d bands in electronic spectra and potentials, measured by cyclic voltammetry. The 3-Mepy complexes exhibit strong single infrared
Cu4O absorptions, while for related 4-Mepy complexes doubly split Cu4O bands were observed. Two strongly overlapped d—d bands in electronic absorption spectra of the 3-and 4-Mepy complexes in nitromethane were resolved by Gaussian fitting. The
4-Mepy ligand produces slightly stronger ligand field than its 3-Mepy analogue. The maxima of high-energy d—d bands are in a linear correlation with the number of bromide ligands. The correlations for corresponding low-energy bands
are considerably deviated from linearity. The halfwave potentials of the complexes in nitromethane correlate with both the
number of bromides and the data of electronic absorption spectra suggesting that the reducing electron at the electrode process
enters the half-filled d
z
2 orbital of the copper(II) atom. The origin of a difference between the 3-and 4-Mepy complexes in their spectral and electrochemical
properties is also discussed. 相似文献
2.
A. I. Kazakov Yu. I. Rubtsov L. P. Andrienko G. B. Manelis 《Russian Chemical Bulletin》1997,46(10):1694-1699
The rates of heat release in the nitrogen dioxide—n-decane system at a molar ratio of nitrogen oxides ton-decane (β) from 2.4·10−3 to 3.1 and gaseous volumes per mole ofn-decane (V(g)) equal to 0.05–4.5 were studied in the 55.2–92.8 °C temperature range. The initial rate of the process is determined by
the interaction of NO2 withn-decane. The equilibrium constants of dissociation of N2O4 inn-decane and Henry's constants of NO2 and N2O4 in ann-decane solution were determined by complex analysis of the thermodynamic equilibrium in the NO2—n-decane system and dependences of the initial rates onV(g) and β. The experimentally observed self-acceleration of the process in the region of high β and lowT values was suggested to be due to the reaction of N2O4 with intermediate oxidation products. The rate constants of the reaction of NO2 withn-decane were compared with analogous values determined in its mixtures with HNO3 solutions.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1789–1794, October, 1997. 相似文献
3.
M. R. Talipov S. L. Khursan R. L. Safiullin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2012,86(2):235-243
The possibility of intramolecular interaction of a nitroso oxide group with an aromatic ring is investigated at the UB3LYP/6-311+G(d,p) and G3MP2B3 levels of theory for a wide series of aromatic nitroso oxides. It is found that this reaction leads to the formation
of a dioxazole cycle, its subsequent decay resulting in opening of the benzene ring and formation of nitriloxide and carbonyl
functional groups. The activation enthalpy of the transformation of phenylnitroso oxide is 75.1 kJ/mol. It is shown that various
sub-stituents at ortho-position (with respect to the nitroso oxide fragment) considerably lower the activation barrier of the investigated transformation,
particularly in case of o,p-dimethoxyphenylnitroso oxide ΔH
≠ = 43.7 kJ/mol. It is concluded that in the case of polyaromatic nitroso oxides, for which intramolecular cyclization is more
typical (ΔH
≠ ∼ 50 kJ/mol), a factor favoring the attack on the ortho-carbon atom is the stabilization of the product’s diene group due to its inclusion in the polyaromatic system. It is established
that sum of these effects leads to a low activation barrier for the transformation of nitroso oxide that forms during the
photooxidizing of 2-azido-1-methoxyphenazine, ΔH
≠ = 19 kJ/mol. It is proposed that due to the low activation energy of some nitroso oxides, their intramolecular cyclization
may be the primary channel of their unimolecular decay. 相似文献
4.
Synthesis And Characterization Of Complexes Of Rare Earth Elements With 1,1-Cyclobutanedicarboxylic Acid 总被引:1,自引:0,他引:1
The complexes of yttrium and lanthanide with 1,1-cyclobutanedicarboxylic acid of the formula: Ln2(C6H6O4)3⋅nH2O, where n=4 for Y, Pr–Tm, n=5 for Yb,Lu, n=7 for La, Ce have been studied. The solid complexes have colours typical of Ln3+ ions. During heating in air they lose water molecules and then decompose to the oxides, directly (Y, Ce, Tm, Yb) or with
intermediate formation. The thermal decomposition is connected with released water (313–353 K), carbon dioxide, hydrocarbons(538–598
K) and carbon oxide for Ho and Lu. When heated in nitrogen they dehydrate to form anhydrous salt and next decompose to the
mixture of carbon and oxides of respective metals. IR spectra of the prepared complexes suggest that the carboxylate groups
are bidentate chelating.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
5.
Sumanta Bhattacharya Shrabanti Bhattacharya Banerjee Kalyan Ghosh Sukalyan Basu Manas Banerjee 《Journal of solution chemistry》2006,35(4):519-539
Electron donor–acceptor (EDA) complex formation of o-chloranil with six different phosphine oxides and tri-n-butyl phosphate (TBP) has been studied in CCl 4 solution by the UV-VIS absorption spectrophotometric technique. An absorption band due to a charge–transfer (CT) transition is observed in the visible region. Utilizing the CT transition energy, the electron affinity of o-chloranil in solution has been calculated. Degrees of charge transfer, and oscillator and transition dipole strengths have also been calculated for all of the investigated EDA complexes. Except for TBP, other phosphine oxides, viz., tri-n-octyl phosphine oxide, tri-n-butyl phosphine oxide, triphenyl phosphine, octyl(phenyl)-N,N-diisobutylcarbamoylphosphine oxide, octyl(phenyl)-N,N-dicyclohexylcarbamoylmethylphosphine oxide and octyl(phenyl)-N,N-diisopropylcarbamoylmethylphosphine oxide have been shown to form stable 1:1 EDA complexes with o-chloranil. The complex of TBP with o-chloranil decays slowly into a secondary product. Formation constants of the EDA complexes have been determined. 相似文献
6.
A. Yu. Teterin M. V. Ryzhkov Yu. A. Teterin K. I. Maslakov T. Reich S. L. Molodtsov 《Journal of Structural Chemistry》2011,52(2):295-303
The structure of the resonant electron emission (REE) spectra of UO2 (REE appears under the excitation with synchrotron radiation near the O4,5(U) absorption edge at ∼100 eV and ∼110 eV) is studied with regard to the X-ray O4,5(U) absorption spectrum of UO2 and a quantitative scheme of molecular orbitals based on the X-ray electron spectroscopy data and the results of a relativistic
calculation of the electronic structure of UO2. The structure of the REE spectra of U3O8 and UO2+x
is studied for comparison, and the effect of the uranium chemical environment in oxides on it is found. The appearance of
such a structure reflects the processes of excitation and decay involving the U5d and electrons of the outer valence MOs (OVMOs,
from 0 to ∼13 eV) and inner valence MOs (IVMOs, from ∼13 eV to ∼35 eV) of the studied oxides. It is noted that REE spectra
show the partial density of states of U6p and U5f electrons. Based on the structure of REE spectra, it is revealed that U5f electrons directly participate (without losing the f nature) in the chemical bonding of uranium oxides and are delocalized within CMOs (in the middle of the band), which results
in the enhancement of the intensity of the REE spectra of CMO electrons during resonances. The U6d electrons are found to be localized near the bottom of the outer valence band and are observed in the REE spectra of the
studied oxides as a characteristic maximum at 10.8 eV. It is confirmed that U6p electrons are effectively involved in the formation of IVMOs, which leads to the appearance of the structure in the region
of IVMO electron energies during resonances. This structure depends on the chemical environment of uranium in the considered
oxides. 相似文献
7.
S. L. Khursan A. M. Nazarov E. M. Chainikova V. D. Komissarov 《Russian Chemical Bulletin》2001,50(5):793-797
The absorption spectra and rate constants of diphenylcarbonyl oxide recombination in a series of solvents and their binary mixtures were determined by flash photolysis. An increase in the solvent polarity causes hypsochromic shift of the maximum in the absorption spectrum of Ph2COO. The analysis of the solvent effect on the recombination rate constant in terms of the four-parameter Koppel—Palm equation shows that the reactivity of carbonyl oxide depends on both specific and non-specific solvations. Quantum chemical B3LYP/6-31G(d) calculations of H2COO and PhHCOO carbonyl oxides as well as the complexes of H2COO with acetonitrile and ethylene in different media were performed using a polarized continuum model. 相似文献
8.
V. Sydorchuk S. Khalameida V. Zazhigalov J. Skubiszewska-Zięba R. Leboda 《Journal of Thermal Analysis and Calorimetry》2010,100(1):11-17
Physicochemical processes during thermal treatment of vanadium and phosphorus oxides mixture (1) as well as with diammonium
hydrophosphate (2) in the closed system (autoclave) have been studied. In the first case, at 300 °C, the defective structure
γ-VOPO4 is formed and in the second case, there was established possibility of synthesis of vanadyl hydrophosphate—the precursor
of vanadyl pyrophosphate (the catalyst of n-butane oxidation to maleic anhydride). At the same time, various phases of mixed ammonium and vanadium phosphates were obtained
at lower and higher temperatures. 相似文献
9.
S. Yu. Ketkov N. A. Isachenkov H. Braunschweig T. Kupfer 《Russian Chemical Bulletin》2009,58(4):682-690
Gas-phase electronic absorption spectra of ansa-(cycloheptatrienylcyclopentadienyl)-chromium complexes with silicon- and germanium-containing bridges were recorded for the
first time. The spectrum of the —(SiMe2)2— bridged compound exhibits a Rydberg structure arising from the transitions originating at HOMO. Shortening of the bridge
causes the Rydberg bands to broaden beyond detection. Density functional calculations were performed to investigate the electron
density distribution in neutral complexes and the corresponding cations. An increase in the angle between the carbocycles
on going from the —(SiMe2)2— bridged com pound to the —SiMe2— and —GeMe2— bridged complexes was shown to cause substantial changes in the composition and energies of the HOMO and Rydberg orbitals.
Delocalization of the HOMO in the —SiMe2— and —GeMe2— bridged molecules leads to broadening of the Rydberg bands in the gas-phase spectra. 相似文献
10.
The reactivity of carbonyl oxides toward benzaldehyde was characterized by thek
33/k
33 ratio, wherek
33 andk
31 are the rate constants of the reactions of RCOO with PhCHO and diphenyldiazomethane Ph2CN2, respectively. Thek
33/k
31 ratios obtained at 60°C in acetonitrile range from 0.61·10−2 (m-BrPh2CN2) to 20·10−2 (Ph2MeCHO). The reactions are probably preceded by the formation of a charge-transfer complex (CTC) with charge transfer from
aldehyde to RCOO. The carbonyl oxide reacts with aldehydes by both the nucleophilic pathway (at the C atom of the—CHO group
to form 1,2,4-trioxolane) and electrophilic pathway (by the attack at the aromatic ring with the intermediate formation of
CTC). In the latter case, either 1,2,4-trioxolane or oxidation products of the phenyl ring are formed.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 650–654, April, 2000. 相似文献
11.
The kinetics of reactions between phenylnitroso oxide, 4-CH3O-, 4-CH3-, or 4-Br-phenylnitroso oxide and triphenylphosphine in acetonitrile at 295 ± 2 K were studied using pulsed photolysis. Only
trans-nitroso oxides enter this reaction. The rate constants of the reaction increase with increasing electron-acceptor properties
of the substituent in the aromatic ring of nitroso oxide; they are on the order of 105 to 106 l mol−1 s−1. The extinction coefficient for trans-4-methylphenylnitroso oxide at 420 nm was estimated at 3.9 × 103 l mol−1 cm−1. 相似文献
12.
The kinetics of reactions of ethylp-nitrophenyl ethylphosphonate with anionic nucleophiles in a detergentless water—oil microemulsion, formed in then-hexane—water—isopropyl alcohol system, was studied. The rate constants of the reactions in the microemulsion are higher than
those in aqueous solutions and increase with increasing isopropyl alcohol: water ratio.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2262–2265, December, 1999. 相似文献
13.
The reactions ofn-cetyl- andn-hexylamines with 4-nitrophenyl esters of tetracoordinated phosphorus acids in chloroform in the presence of 2-hydroxyethyldimethylpentadecylammonium
bromide and the influence of the latter on the acid—base equilibrium of the bromphenol blue dye (BPB) were studied by the
spectrophotometric method. In the presence of reversed micelles of the cationic surfactant, the observed rate constant of
aminolysis increases by more than two orders of magnitude. The catalytic efficiency of the micelles increases as the concentration
of the long-chain amine decreases and on going from the latter to a short-chain amine. The acid—base equilibrium of BPB in
micellar solutions is shifted due to the formation of a complex between the surfactant and the BPB dianion.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2125–2128, December, 1997. 相似文献
14.
R. S. B. Reddi V. S. A. Kumar Satuluri U. S. Rai R. N. Rai 《Journal of Thermal Analysis and Calorimetry》2012,107(1):377-385
Solid–liquid phase equilibrium data of three binary organic systems, namely, 3-hydroxybenzaldehyde (HB)—4-bromo-2-nitroanilne
(BNA), benzoin (BN)—resorcinol (RC) and urea (U)—1,3-dinitrobenzene (DNB), were studied by the thaw–melt method. While the
former two systems show the formation of simple eutectic, the third system shows the formation of a monotectic and a eutectic
with a large immiscibility region where two immiscible liquid phases are in equilibrium with a liquid of single phase. Growth
kinetics of the pure components, the monotectic and the eutectics, studied by measuring the rate of movement (v) of solid–liquid interface in a thin U-tube at different undercoolings (ΔT) suggests the applicability of the Hillig–Turnbull’s equation: v = u (ΔT)
n
, where v and n are the constants depending on the nature of the materials involved. The thermal properties of materials such as heat of
mixing, entropy of fusion, roughness parameter, interfacial energy, and excess thermodynamic functions were computed from
the enthalpy of fusion values, determined by differential scanning calorimeter (Mettler DSC-4000) system. The role of solid–liquid
interfacial energy on morphologic change of monotectic growth has also been discussed. The microstructures of monotectic and
eutectics were taken which showed lamellar and federal features. 相似文献
15.
Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) 3-methylglutarates were prepared as solids with general formula MC6 H8 O4 ×n H2 O, where n =0–8. Their solubilities in water at 293 K were determined (7.0×10−2 −4.2×10−3 mol dm−3 ). The IR spectra were recorded and thermal decomposition in air was investigated. The IR spectra suggest that the carboxylate
groups are mono- or bidentate. During heating the hydrated complexes lose some water molecules in one (Mn, Co, Ni, Cu) or
two steps (Cd) and then mono- (Cu) or dihydrates (Mn, Co, Ni) decompose to oxides directly (Mn, Cu, Co) or with intermediate
formation of free metals (Co, Ni). Anhydrous Zn(II) complex decomposes directly to the oxide ZnO.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
The triethanolamine complexes, [M(tea)2]sq·nH2O, (n=2 for Co(II), n=0 for Ni(II), Cu(II) and n=1 for Cd(II), tea=triethanolamine, sq2−=squarate), have been synthesized and characterized by elemental analyses, magnetic susceptibility and conductivity measurements,
UV-Vis and IR spectra, and thermal analyses techniques (TG, DTG and DTA). The Co(II), Ni(II) and Cu(II) complexes possess
octahedral geometry, while the Cd(II) complex is monocapped trigonal prismatic geometry. Dianionic squarate behaves as a counter
ion in the complexes. The thermal decomposition of these complexes takes place in three stages: (i) dehydration, (ii) release of the tea ligands and (iii) burning of organic residue. On the basis of the first DTGmax of the decomposition, the thermal stability of the anhydrous complexes follows the order: Ni(II), 289°C>Co(II), 230°C>Cu(II),
226°C>Cu(II), 170°C in static air atmosphere. The final decomposition products — the respective metal oxides — were identified
by FTIR spectroscopy. 相似文献
17.
N. Sh. Lebedeva R. S. Kumeev G. A. Al’per E. V. Parfenyuk A. S. Vashurin T. V. Tararykina 《Journal of solution chemistry》2007,36(6):793-801
For the first time the interactions between zinc(II)tetra-4-alkoxybenzoyloxiphthalocyanine (Zn(4—O—CO—C6H4—OC11H23)Pc) and 1,4-diazabicyclo[2.2.2]octane (DABCO) in o-xylene and chloroform have been studied by calorimetric titration and NMR and electron absorption spectroscopic methods.
It has been found that in o-xylene at concentrations of Zn(4—O—CO—C6H4—OC11H23)Pc higher than 6×10−4 mol⋅L−1
π–π dimers species are formed (λ
max= 685 nm). Additions of DABCO to the solution up to mole ratio 1 : 8 (Zn(4—O—CO—C6H4—OC11H23)Pc : DABCO) lead to a shift of the aggregation equilibrium towards monomer species due to formation of monoligand axial complexes.
Further increasing the DABCO concentration results in formation of Zn(4—O—CO—C6H4—OC11H23)Pc—DABCO—Zn(4—O—CO—C6H4—OC11H23)Pc sandwich dimers (λ
max= 675 nm). 相似文献
18.
Spectral,
magnetic and thermal investigations of some d-electron
element 3-methoxy-4-methylbenzoates
Conditions
for the preparation of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) 3-methoxy-4-methylbenzoates
were investigated and their quantitative composition and magnetic moments
were determined. The IR spectra and powder diffraction patterns of the complexes
prepared of general formula M(C9H9O3)2·nH2O (n=2
for Mn, Co n=1 for Ni, Cu, n=0
for Zn, Cd) were prepared and their thermal decomposition in air was studied.
Their solubility in water at 293 K is of the order 10–2
(Mn)–10–4 (Cu) mol dm–3.
IR spectra of the prepared 3-methoxy-4-methylbenzoates suggest that carboxylate
groups are bidentate bridging. The magnetic moments for the paramagnetic complexes
of Mn(II), Co(II), Ni(II) and Cu(II) attain values 5.50, 4.45, 3.16 and 1.79
B. M., respectively. During heating the hydrated complexes lose crystallization
water molecules in one step and then the anhydrous complexes decompose directly
to oxides MO and Mn3O4. Only Co(II) complex decomposes to Co3O4
with intermediate formation CoO. 相似文献
19.
The reduction of chromium, nickel, and manganese oxides by hydrogen, CO, CH4, and model syngas (mixtures of CO + H2 or H2 + CO + CO2) and oxidation by water vapor has been studied from the thermodynamic and chemical equilibrium point of view. Attention was
concentrated not only on the convenient conditions for reduction of the relevant oxides to metals or lower oxides at temperatures
in the range 400–1000 K, but also on the possible formation of soot, carbides, and carbonates as precursors for the carbon
monoxide and carbon dioxide formation in the steam oxidation step. Reduction of very stable Cr2O3 to metallic Cr by hydrogen or CO at temperatures of 400–1000 K is thermodynamically excluded. Reduction of nickel oxide (NiO)
and manganese oxide (Mn3O4) by hydrogen or CO at such temperatures is feasible. The oxidation of MnO and Ni by steam and simultaneous production of
hydrogen at temperatures between 400 and 1000 K is a difficult step from the thermodynamics viewpoint. Assuming the Ni—NiO
system, the formation of nickel aluminum spinel could be used to increase the equilibrium hydrogen yield, thus, enabling the
hydrogen production via looping redox process. The equilibrium hydrogen yield under the conditions of steam oxidation of the Ni—NiO system is, however,
substantially lower than that for the Fe—Fe3O4 system. The system comprising nickel ferrite seems to be unsuitable for cyclic redox processes. Under strongly reducing conditions,
at high CO concentrations/partial pressures, formation of nickel carbide (Ni3C) is thermodynamically favored. Pressurized conditions during the reduction step with CO/CO2 containing gases enhance the formation of soot and carbon-containing compounds such as carbides and/or carbonates. 相似文献
20.
Abdelwareth A. O. Sarhan Mohammed S. Ibrahim Mostafa M. Kamal Kaiko Mitobe Taeko Izumi 《Monatshefte für Chemie / Chemical Monthly》2009,9(11):315-323