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1.
The compounds K 4Ti(O 2) 4·2H 2O, K 3Ta(O 2) 2F 4 and K 2V 2O 3(O 2) 2F 2 undergo photolysis in the solid state. The photolysis kinetics obey the parabolic rate equation p = kt1/2 and indicate a monoexcitation process for the photolysis. These features are similar to those reported previously for peroxo complexes. The mechanism of evolution of oxygen reported earlier appears to be the same in all these solids. 相似文献
2.
The synthesis of dimethyl {2-[3-(4-nitrophenyl)-1 H-pyrazol-5-yl]ethyl}malonate monohydrate 1, C 16H 17N 3O 6·H 2O was performed and the molecular structure has been studied by using NMR, single crystal X-ray diffraction and ab initio calculations. The title compound presents a pyrazole ring (N1 to C5), a phenyl ring (C1″ to C6″) attached to C3 and the ethylene dimethyl malonate frame (C1′ to C7′) attached to C5. The torsion angle defined by N2C3C1″C2″ (−12.26°) showed that pyrazole and phenyl rings are not in the same plane. Monohydration in (1) is present in the structure by a NHOH 2 hydrogen bonding, with a bond length of 1.782 Å. Experimental and theoretical evidences indicated the preference of the 3-tautomer over the corresponding 5-tautomer in the titled pyrazole. 相似文献
3.
The decomposition of Li 2S 2O 6·2 H 2O, Na 2S 2O 6·2 H 2O, and MgS 2O 6·7 H 2O has been studied using TG and DTG. Both sodium and lithium dithionates dehydrate in one step. Magnesium dithionate dehydrates in three separate steps. All three of the dithionates undergo further decomposition and lose sulfur dioxide to give stable sulfates. Kinetic parameters are presented for these reactions. 相似文献
4.
The linear attenuation coefficients in aqueous solutions of some chlorides and sulphates, viz. MgCl 2·6H 2O, CaCl 2, SrCl 2·6H 2O, BaCl 2·2H 2O, Na 2SO 4, K 2SO 4 and MgSO 4·7H 2O were determined at 81, 356, 511, 662, 1173 and 1332 keV by the γ-ray transmission method in a good geometry setup. From the precision measured densities of these solutions, mass attenuation coefficients were then obtained which varied systematically with the corresponding changes in the concentrations (g/cm 3) of these solutions. A comparison between experimental and theoretical values of attenuation coefficients has shown that the study has potential application for the determination of attenuation coefficients of solid solutes from their solutions without obtaining them in pure crystalline form. 相似文献
5.
Using a variable temperature STM to trace in detail the path of single particle movement, it is possible to derive diffusion parameters of individual atoms and molecules on solid surfaces as well as to probe the mechanisms. Below ˜370 °C, O 2 molecules adsorb on Si(111)-7×7 surfaces at the top site of Si-adatoms as bright image spots. An O 2 molecule can hop between two adatom sites within the half unit cell it adsorbs via two rest-atom sites. Above this temperature, it can either hop out of the half cell, or can go through other reaction pathways. In contrast, for H atoms, the adsorption sites are rest-atom sites. An H atom darkens the rest-atom in filled state image, but the surrounding adatoms will appear brighter because of a reverse charge transfer. Above ˜280 °C, it can hop to a neighbor rest atom site within the half cell via an adatom site. The adatom in the short lived intermediate state appears darker because of the saturation of its dangling bond. Above ˜340 °C, it can hop out of the half cell via two adatom sites. Thus diffusion of H and O 2 on this surface is achieved by hopping of chemical bonds via intermediate states. We have also derived site and pathway-specific activation energies and frequency factors and the potential energy curves for the hopping of O 2 and H on Si(111)-7×7 surfaces. 相似文献
6.
Hydrated strontium borate, SrB 4O 7·3H 2O, has been synthesized and characterized by XRD, FT-IR, DTA-TG and chemical analysis. The molar enthalpy of solution of SrB 4O 7·3H 2O in 1 mol dm −3 HCl(aq) was measured to be (21.15 ± 0.29) kJ mol −1. With incorporation of the previously determined enthalpies of solution of Sr(OH) 2·8H 2O(s) in [HCl(aq) + H 3BO 3(aq)] and H 3BO 3 in HCl(aq), and the enthalpies of formation of H 2O(l), Sr(OH) 2·8H 2O(s) and H 3BO 3(s), the enthalpy of formation of SrB 4O 7·3H 2O was found to be −(4286.7 ± 3.3) kJ mol −1. 相似文献
7.
The infrared spectra of isotopically dilute (matrix-isolated HDO molecules) isostructural compounds M(HCOO) 2·2H 2O (M=Mn,Fe,Co,Ni,Zn,Cu) are presented and discussed in the region of the OD stretching modes. According to the structural data the compounds under study are divided into two groups: in M(HCOO) 2·2H 2O (M=Mn,Ni,Zn) the H 2O(1) molecules form stronger hydrogen bonds as compared to H 2O(2); in M(HCOO) 2·2H 2O (M=Fe,Co,Cu) the H 2O(2) molecules form stronger hydrogen bonds as compared to the H 2O(1) molecules. The influence of the metal–water interactions (synergetic effect) and the unit-cell volumes (repulsion potential of the lattice) on the hydrogen bond strength within the isostructural series is discussed. The wavenumbers of the uncoupled OD stretching modes of the HDO molecules influenced by guest ions (Cu 2+ ions matrix-isolated in M(HCOO) 2·2H 2O and M 2+ ions matrix-isolated in Cu(HCOO) 2·2H 2O) are presented and commented. For example, the analysis of the spectra reveals that when Cu 2+ ions are included in the structure of M(HCOO) 2·2H 2O the hydrogen bonds of the type M–OH 2OCHO–Cu are considerably weaker as compared to those of the same type formed when M 2+ ions are included in the structure of Cu(HCOO) 2·2H 2O if the cations remain unchanged. 相似文献
8.
The solid–liquid equilibria of the ternary system H 2O–Fe(NO 3) 3–Co(NO 3) 2 were studied by using a synthetic method based on conductivity measurements. Two isotherms were established at 0 and 15 °C, and the stable solid phases which appear are the iron nitrate nonahydrate (Fe(NO3)3·9H2O), the iron nitrate hexahydrate (Fe(NO3)3·6H2O), the cobalt nitrate hexahydrate (Co(NO3)2·6H2O) and the cobalt nitrate trihydrate (Co(NO3)2·3H2O). 相似文献
9.
A new sodium cobalt carbonate hydroxide hydrate, Na 2Co 8(CO 3) 6(OH) 6·6H 2O, has been prepared at room temperature by treatment of Co(OH)NO 3·H 2O with a concentrated aqueous solution of NaHCO 3. X-Ray powder diffractometry and the results of the chemical analyses show that the compound is isotypical to Na 2Ni 8(CO 3) 6(OH) 6·6H 2O —kambaldaite, a unique mineral with no known synthetic or natural analogues. 相似文献
10.
By using the “ simultaneous Q-DTA, Q-TG measuring technique” elaborated recently, conditions near to the requirements of thermodynamics can be created, thus the “normalized” course of curves taken by this method, their characteristic temperatures or the values measured for the enthalpy change can be considered to be near to the theoretical values. For testing this new method, CuSO4·5H2O, MnSO4·5H2O, Mg(NO3)2·6H2O and Na2SO4·10H2O have been investigated. These model substances can be prepared in stoichiometric composition free of impurities, their decomposition mechanism is well-known, thus the effect of the altered experimental conditions by the simultaneous Q-DTA, Q-TG method on the course of their dehydration can be calculated. 相似文献
11.
用氮蓝四唑(NBT)、细胞色素C还原及DMPO自旋捕集技术等三种方法分别在磷酸缓冲液、甲醇及二甲基亚砜(DMSO)中,测定超氧化物阴离子自由基(O 2-·)。并与核黄素光照及邻苯三酚自氧化等二种已知产生O 2-·系统相比较。结果表明:血卟啉衍生物光敏反应原初过程O 2-·产率很低,水及DMSO等溶剂对OT的测定均有影响。 相似文献
12.
Thermal decomposition taking place in solid state complex, NiC 2O 4·2H 2O, has been investigated in air by means of TG–DTG/DTA, DSC, XRD. TG–DTG/DTA curves showed that the decomposition proceeds through two well-defined steps with DTA peaks closely corresponding to the weight loss obtained. XRD showed that the final decomposition product of NiC 2O 4·2H 2O was NiO. Kinetics analysis of NiC 2O 4·2H 2O decomposition steps was performed under non-isothermal conditions. The activation energies were calculated through Friedman and Flynn–Wall–Ozawa (FWO) methods, and the most possible kinetic model function has been estimated through the multiple-linear regression method. The activation energies for the two decomposition steps of NiC 2O 4·2H 2O were 171.1 ± 4.2 and 174.4 ± 8.1 kJ/mol, respectively. 相似文献
13.
The photolysis of CH 3ReO(O 2) 2·H 2O in methylene chloride yields, like the thermolysis, molecular oxygen in the triplet spin state. The quantum yield QPh of photolysis shows a remarkable dependence the wavelength, increasing from 0.12 at 365 nm to 1.0 at 248 nm. One single excited state is responsible for this behaviour. The wavelength-dependent quantum yield profile corresponds in a first approximation to the ratio between the LMCT-band and the total absorption spectrum was made on a mathematical basis using symmetrical Gauss curves. This is the first time that a fluorescence and phosphorescence emission of an alkyl transition-metal complex of d 0-configuration has been detected, thus allowing for the determination of both the S1 and the T1-energy levels. The quantum yield of the fluorescence ( QF) is below 10 −3; that of the phosphorescence is below 0.04. ZusammenfassungDie Photolyse von CH3ReO(O2)2·H2O in Methylenchlorid führt ebenso wie die Thermolyse dieses Komplexes zur Abspaltung von molekularem Sauerstoff im Triplettgrundzustand. Die Photolyse-Quantenausbeute QPh zeigt eine bemerkenswerte Abhängigkeit von der eingerstrahlten Wellenlänge und steigt von 0.12 bei 365 nm bis zu 1.0 bei 248 nm an. Hierfür kann hauptsächlich ein einziger angeregter Zustand verantwortich gemacht werden. Der Kurvenverlauf der wellenlängenabhängigen Quantenausbeute entspricht in guter Näherung dem Verhältnis der LMCT-Bande zum Gesamtabsorptionsspektrum. Die Zerlegung des Absorptionsspektrums in die einzelnen Banden erfolgte durch rechnerische Kurvenanalyse in symmetrische Gauss-Kurven. Erstmals konnte die Fluoreszenz- und die Phosphoreszenz-emission eines alkylhaltigen d0-Übergangsmetall-Komplexes detektiert werden und somit sowohl die S1-als auch die T1-Energielage bestimmt werden. Die Quantenausbeute der Fluoreszenz QF ist kleiner als 10−4, die Phosphoreszenzquantenausbeute beträgt weniger als 0.04. 相似文献
14.
Cellulose acetate (CA) membranes containing RuCl 3·3H 2O and RhCl [P(C 6H 5) 3] 3 were prepared reproducibly. Such membranes, on treatment with CO, formed metal-carbonyl species at relatively low temperature. The Ru-carbonyls formed in CA were quite stable at 40°C in comparison with the Rh-carbonyl species and, interestingly, there was no permeation of CO gas through the ruthenium-containing CA membrane at 40°C. However, the permeation of other gas molecules, such as H 2, N 2 and O 2, through the same membrane was reduced only slightly, probably due to the cross-linking effect of the transition metal complexes in CA. It was found that essentially pure H 2 gas could be recovered from a 1: 1 mixture of H 2 and CO gases using ruthenium-containing cellulose acetate membranes. 相似文献
15.
3,4-Epoxyalcohols undergo regioselective cyclization in the presence of CeCl 3·7H 2O in ref1uxing acetonitrile to afford tetrahydrofuran derivatives in good yields. On the other hand epoxyalcohols afforded 1-chloro-3-substituted-2-propanols under microwave irradiation using CeCl 3·7H 2O supported on SiO 2 under solvent-free conditions. 相似文献
16.
New double salts Ag 2C 2·6AgO 2CCHF 2 (1), [HPyCH 2OH][Ag 9(C 2)(CF 3CO 2) 9(HPyCH 2OH)(H 2O)]·0.5H 2O (PyCH 2OH=4-(hydroxymethyl)pyridine) (2), Ag 2C 2·5CF 3SO 3Ag·2MeCN·2H 2O (3) and Ag 2C 2·8CF 3SO 3Ag·2EtCN·3H 2O (4) have been synthesized by dissolving Ag 2C 2 in an aqueous solution of the corresponding silver salt followed by the addition of an ancillary ligand. Complex 1 has a three-dimensional structure in which unprecedented basket-like silver cages are inter-connected by difluoroacetate ligands. In 2, centrosymmetric (C 2) 2@Ag 14 double cages with each half taking the shape of a triangulated dodecahedron are linked through additional silver atoms to generate an infinite chain, and unsupported silver(I)–silver(I) interactions exist between neighboring chains. Of the two independent 4-(hydroxymethyl)pyridinium ions in 2, one acts in the O-ligating mode, which is observed for the first time, while the other merely serves to provide charge balance and space-filling. Both 3 and 4 are layer-type structures in which the basic building unit is a distorted monocapped octahedron and monocapped trigonal prism, respectively. 相似文献
17.
Low-temperature heat capacities of the complex Zn(Thr)SO 4·H 2O (s) have been precisely measured with a small sample adiabatic calorimeter over the temperature range from 78 to 373 K. The initial dehydration temperature of the complex ( Td=325.50 K) has been obtained by analysis of the heat-capacity curve. The experimental values of molar heat capacities have been fitted to a polynomial equation by least square method. The standard molar enthalpy of formation of the complex has been determined from the enthalpies of dissolution (Δ dHmΘ) of [ZnSO 4·7H 2O (s) +Thr (s)] and Zn(Thr)SO 4·H 2O (s) in 100 ml of 2 mol dm −3 HCl solvent as: Δ fHm,Zn(Thr)SO4·H2OΘ=−2111.7±3.4 kJ mol −1. These experiments were made by using an isoperibol solution calorimeter at 298.15 K. 相似文献
18.
The compound [Ru 2(μ-O 2CCH 3) 4(THF) 2]BF 4 (I) containing the Ru 25+ unit was prepared by reaction of Ru 2Cl(μ-O 2CCH 3) 4 with AgBF 4 in THF. This compound, in contrast with Ru 2Cl(μ-O 2CCH 3) 4, is soluble in several polar organic solvents and reacts in THF with OPPh 3 and PPh 3 giving [Ru 2(μ-O 2CCH 3) 4(OPPh 3) 2]BF 4·CH 2Cl 2 (II) and [Ru(μ-O 2CCH 3)(O 2CCH 3)(PPh 3)] n (III), respectively. The complex II has been also obtained as hexafluorophosphate [Ru 2(μ-O 2CCH 3) 4(OPPh 32]PF 6·CH 2Cl 2 (IV) by treatment of Ru 2Cl(μ-O 2CCH 3) 4 with an excess of NOPF 6 and PPh 3 in methanol. In this reaction the triphenylphosphine oxide is generated by oxidation of the triphenylphosphine. 相似文献
19.
Ternary terbium complexes with p-aminobenzoic acid (HL), [TbL 3(DMSO)(H 2O)] 2 (1), [TbL 3(DMF)(H 2O)] 2 (2) and [TbL 3(Bpy)(H 2O)] 2·2H 2O (3) (DMSO=dimethyl sulfoxide, DMF= N, N- dimethylformamide, Bpy=2, 2′- bipyridyl) have been synthesized, and their crystal structures determined. The luminescence properties of these complexes, including both the emission quantum yield and the fluorescence lifetime, have been investigated. The effect of a second ligand on the crystal structure and luminescence property of the ternary terbium p-aminobenzoic acid complexes, and the relationship between luminescence properties and crystal structure, including coordination mode of the L − ligand and the characteristics of a second ligand, are discussed. 相似文献
20.
Trichlorides of the lanthanide elements Ln=Ce–Lu form: (a) isotypic hexahydrates LnCl 3·6H 2O with a coordination number (CN) 8 for the Ln 3+ ions. (b) Two isotypic groups of trihydrates LnCl 3·3H 2O, in the first group Ln=Ce-Dy the CN is 8; the structure of the second group Ln=Er–Lu is unknown. With Ho no trihydrate exists; a dihydrate is formed. (c) Two isotypic groups of monohydrates LnCl 3·H 2O with unknown structure – Ln=Ce–Dy and Ln=Ho–Lu. For all compounds and for anhydrous chlorides LnCl 3 solution enthalpies were measured with an isoperibolic calorimeter. The Δ solH0 values do not depend only on the difference (lattice enthalpies/hydration enthalpies), but also on the state in solution. According to Spedding the CN of the Ln 3+ ions against water changes from 9 to 8 between Nd and Sm, causing minima in the series of solution enthalpies. Dihydrates LnCl 3·2H 2O are found for Ln=Ce, Pr, Nd, Sm and presumably for Eu and Gd. They are not yet well characterised. 相似文献
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