共查询到20条相似文献,搜索用时 564 毫秒
1.
W. Earle Waghorne 《Monatshefte für Chemie / Chemical Monthly》2003,29(2):655-667
The solubilities of the silver halides in three non-aqueous solvents: methanol, acetonitrile, and dimethylsulfoxide, and
in their aqueous mixtures, are reviewed. Values for the solubility product, K
SO
, the enthalpies of solution, Δ
sol
H
o
, and the equilibrium products for AgX
(i−1)−
i
silver halide complexes, β
i
, are listed and, where possible, compared. The solvent systems provide examples for three types of mixed aqueous solvent
system: aqueous alcohol mixtures and aqueous mixtures with dipolar aprotic solvents that are weakly or strongly basic. The
experimental data are discussed in terms of the solvation of the silver and halide ions in the mixed solvents. 相似文献
2.
Equilibrium geometries, force constants, barriers to linearity, charge distributions, dipole moments, and electron spin density of HOO, HOS, HSO, and HSS radicals are calculated by CNDO/2 and INDO methods using respectively the original and some recently introduced scheme of parametrization. Three sets of calculations, namely, CNDO/2(sp), CNDO/2(spd), and INDO, are performed, and the results are compared with the ab initio and experimental values, wherever available. A good agreement is obtained for geometry in the case of CNDO/2 (sp) and INDO calculations. The performance of CNDO/2 (spd) calculations in this regard is quite unreliable. The stretching force constants are considerably overestimated by all the methods, while the bending force constants are in reasonable agreement with the ab initio values. With respect to dipole moments, the CNDO/2 values are in better agreement with the ab initio results than the INDO values. In all the cases, the dipole moment vector directions are in complete disagreement with the ab initio predictions. 相似文献
3.
Ab initio calculations including electron correlation (on the PNO-CI and CEPA-PNO levels) are carried out for the isovalence electronic molecules H2CO, H2CS and H2SiO, and for comparison also for H2O and CO. The CEPA equilibrium distances are accurate to within 0.003 Å, while SCF results show significantly larger errors. The harmonic force constants on CEPA level are satisfactory as well, but for stretching of double or triple bonds inclusion of singly substituted configurations is imperative. Dipole moments were obtained with an error of 0.1 Debye from CEPA calculations with sufficiently large basis sets and inclusion of singly substituted configurations. The dipole polarizabilities are less sensitive to correlation effects but require larger basis sets.The population analysis reveals that the SiO bond in H2SiO is highly polar and thatd-AO's cannot be regarded as valence AO's in any of the molecules of this study. The binding energy of H2SiO (with respect to H2Si(1
A
1) + O(3
P)) is predicted as 140 ± 5 kcal/mol. The contributions of different pairs in terms of localized orbitals to the correlation energy of the molecules of this study are analyzed. 相似文献
4.
W. Earle Waghorne 《Monatshefte für Chemie / Chemical Monthly》2003,134(5):655-667
Summary. The solubilities of the silver halides in three non-aqueous solvents: methanol, acetonitrile, and dimethylsulfoxide, and
in their aqueous mixtures, are reviewed. Values for the solubility product, K
SO
, the enthalpies of solution, Δ
sol
H
o
, and the equilibrium products for AgX
(i−1)−
i
silver halide complexes, β
i
, are listed and, where possible, compared. The solvent systems provide examples for three types of mixed aqueous solvent
system: aqueous alcohol mixtures and aqueous mixtures with dipolar aprotic solvents that are weakly or strongly basic. The
experimental data are discussed in terms of the solvation of the silver and halide ions in the mixed solvents.
E-mail: Earle.Waghorne@ucd.ie
Received September 30, 2002; accepted October 29, 2002
Published online April 7, 2003
RID="a"
ID="a" Dedicated to Prof. Heinz Gamsj?ger on the occasion of his seventieth birthday 相似文献
5.
A. A. El-Khouly M. A. H. Hafez I. M. M. Kenawy 《Russian Journal of Electrochemistry》2006,42(3):225-232
Some kinetic and activation thermodynamic functions for the electrodeposition of palladium, thallium, and tellurium from the
best selected baths, viz. niclosamide bath [5-chloro-N-(2-chloro-4-nitrophenyl)-2-hydroxybenzamide] for Pd, alizarin red bath
for Tl, and salicylaldehyde bath for Te, are determined. Reaction rate constant (k), half-lifetime (t
1/2), activation energy (E
a), and such activation thermodynamic parameters as entropy change (ΔS*), enthalpy change (ΔH*), and Gibbs free energy (ΔG*) are calculated by applying the rate theory of the first-order reaction and the Eyring theory of the reaction rate. The
effect of temperature change in the range of 30–60°C on the above parameters is studied and thoroughly discussed. The effect
of metal type on both the reaction rate and the activation energy is also investigated.
Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 3, pp. 264–271.
The text was submitted by the authors in English. 相似文献
6.
Ab initio molecular orbital methods at the CBS-QB3 level of theory have been used to study the structure and gas-phase stability of various tautomers and rotamers of N-hydroxyurea, N-hydroxythiourea, and N-hydroxysilaurea, their anions and protonated forms. The geometries of N-hydroxyurea, N-hydroxythiourea, and N-hydroxysilaurea, their anions and cations were optimized at the Becke3LYP/CBSB7 level of theory. For all compounds studied, the amidic form is computed to be substantially more stable than the iminolic tautomer. N-Hydroxyurea and its thio and sila derivatives are computed to behave as Nacids in the gas phase. These compounds are in gas-phase weak acids with a calculated acidity of about 1425 to 1355 kJ-mol–1. Basicities increase in the order: N-hydroxyurea < N-hydroxythiourea < N-hydroxysilaurea. The most stable protonated structures are represented by several isomers with almost equal stability. Thus, in the N-hydroxyurea, N-hydroxythiourea, and N-hydroxysilaurea, both protonation at the double bonded (C=O, C=S and Si=O) oxygen and sulfur atoms, as well as the protonation at the N(H)OH nitrogen basic center is equally probable. The experimental pK
a
value (10.6) of N-hydroxyurea and the computed value (9.7) for its monohydrated complex with the specifically hydrogen-bonded water molecule to the ionizable OH group are in a good agreement. The experimental partition coefficient of N-hydroxyurea is best reproduced by the Alog Ps method. The formation of nitroxide radical in the reaction of N-hydroxyurea and its sulfur and silicon substituted derivatives with the phenol radical is an exothermic process. Thus, the \bondN(H)OH moiety of these compounds may quench the structurally related tyrosyl radicals in the active site of ribonucleotide reductase. 相似文献
7.
The dissociation constants for o-carboxyphenylhydrazoethylacetoacetate (o-CPHEA) ligand, as well as the stability constants for the divalent metal complexes of Cu, (II), Ni (II), Co (II), Zn (II)and Cd (II) ions, have been calculated pH-meterically in different solvents. The dissociation constans pK1=4.10 and pK2=10.55 of the insoluble organic ligand are calculated in aqueous medium. The effect of solvents, the relation between stabilities and both electronegativities and ionization potential are studied. 相似文献
8.
Juan M. Antelo Florencio Arce Marí C. Castro Juan Crugeiras Juan C. Prez-Moure Pilar Rodríguez 《国际化学动力学杂志》1995,27(7):703-717
The formation of N-chlorobutylamines is a reaction of order one with respect to hypochlorite and amine, and order ?1 with respect to OH?. Kinetic studies show that N-chlorobutylamines undergo decomposition in basic aqueous media, and disproportination (with formation of N,N-dichloramines) in acidic media, mechanisms are put forward for both these processes. © 1995 John Wiley & Sons, Inc. 相似文献
9.
Hui Liu Fang Wang Gui‐Xiang Wang Xue‐Dong Gong 《Journal of computational chemistry》2012,33(22):1790-1796
The ? NH2, ? NO2, ? N3, ? NHNO2, and ? ONO2 substitution derivatives of PYX (2,6‐bis(picrylamino)‐3,5‐dinitropyridine) were studied at the B3LYP/6‐31G** level of density functional theory. The sublimation enthalpies and heats of formation (HOFs) in gas phase and solid state of these compounds were calculated. The theoretical predicted density (ρ), detonation pressure (P), and detonation velocity (D) showed that these derivatives have better detonation performance than PYX. The effects of substituent groups on HOF, ρ, P, and D were discussed. The order of contribution of various groups to P and D was ? ONO2 > ? NO2 > ? NHNO2 > ? N3 > ? NH2. Sensitivity was evaluated using the frontier orbital energies, bond orders, bond dissociation enthalpies (BDEs), and characteristic heights (h50). The trigger bonds in the pyrolysis process for these PYX derivatives may be Ring‐NO2, NH? NO2, or O? NO2 varying with the substituents. The h50 of most compounds are larger than that of CL‐20, and those of ? NH2, ? NO2, and most ? ONO2 derivatives are larger than that of RDX. The BDEs of the trigger bonds of all but the ? ONO2 derivatives are sufficiently large. Taking both detonation performance and sensitivity into consideration, some derivatives of PYX may be good candidates of explosives. © 2012 Wiley Periodicals, Inc. 相似文献
10.
Roland Schmid 《Monatshefte für Chemie / Chemical Monthly》2001,132(11):1295-1326
Summary. Following a critical survey of the vast recent literature, the state of the art may be summarized as follows:
(A) Water structure. The key is appreciating the next-nearest neighbour aspect. Thus, liquid water may be conceived as a fluctuating
mixture of broadly two groups of structure elements: (i) an open ice-Ih-type outer neighbour bonding at about 4.5 ? and (ii) a dense ice-II-type outer neighbour bonding at about 3.4 ?. On the other hand, the nearest neighbour distance of about 2.8 ? and the number of these neighbors (4) is very similar in the solid and liquid state. The characterization
of the two states may be directed either by the geometry of the H-bonds (more linear H-bonds in (i) and more bent H-bonds in (ii) or by the bonding forces operating (H-bonding favours the ordered open state (i), oxygen–oxygen interactions favour the random dense state (ii). Basically, the nature of liquid water can be understood in terms of a competition between H-bond (Coulomb) and dispersion (van der Waals) forces. Since the bonding characteristics in crystalline phases carry over to the liquid state, any molecular dynamics (MD)
model of the liquid would have first of all to reproduce well the ice polymorph structures under appropriate thermodynamic
conditions.
(B) Hydrophobic effect. The two classic approaches, i.e. the clathrate cage model and the cavity-based model, appear to be just different perspectives on the same physics. The particular
features of water are (i) the small molecular size or, more specifically, the small size of the space between water molecules and the low expansibility,
and (ii) the structure of the water molecule with the same number of donor and acceptor sites arranged tetrahedrally. Due to (i), cavity formation is particularly demanding, and this is the main contributor to the hydrophobic effect. This is mitigated
by the capability of water, due to (ii), to form a cage around a nonpolar solute without sacrificing much of the H-bonding; rather, H-bonding networks are stabilized
by the presence of guest molecules. In view of the tangential orientation of the first-sphere waters, such a cage can be compared
with an elasticated net effecting strong solute–solvent dispersive interactions, rendering the solubility of nonpolar gases
exothermic at room temperature. Furthermore, cavity formation largely determines the excess entropy, whereas dispersive forces
determine the excess enthalpy. This gives rise to compensation behaviour when the solute size varies. Whereas an increase
in solute size enhances the cavity formation energy, polarizability is also increased, and this leads to stronger solute–water
interaction. Unfortunately, present models of cavity formation predict positional entropies that are far in excess of the
experimental entropies so that orientational contributions due to cage formation are hard to accommodate.
(C) Like-dissolves-like rule. The number of exceptions is dramatically reduced if the term polarity is given a broader meaning.
Instead of identifying it solely with dipolarity, it should also include higher multipolar properties, in particular quadrupolarity.
Quadrupolar solvent effects on solvation and reactivity are receiving increasing attention, particularly in low dielectric
solvents.
Received May 8, 2001. Accepted (revised) May 23, 2001 相似文献
11.
Yongfang Zhao Tingkun Gu Soufu Pan Jing Sun 《International journal of quantum chemistry》1997,61(6):953-957
The equilibrium geometries and fundamental frequencies of Na2S are calculated at HF, MP2(FC, FU), and MP3 with the 6–31G(d) basis set and at HF and MP2(FC, FU) with the 6–31G(d) basis set, respectively. The total energy at MP2(FU)/6–31G(d)-optimized geometry is computed at MP4 with 6–311G(d, p), 6–311 + G(d, p), and 6–311G(2df, p), at QCISD(T)/6–311G(d, p), and at MP2/6–311G(3df, 2p) levels, respectively. The dissociation energy, the atomization energy, and the heat of formation for Na2S are evaluated using the G1 and G2 models. The calculated results indicated that Na2S in its ground state was a bent structure (C2v). Electron correlation corrections on the bending angle are very significant. The equilibrium geometrical parameters are Re(Na-S) = 2.45 Å and ∠Na-S-Na = 111.13° at the MP2(FU)/6–31G(d) level. The theoretically estimated dissociation energy, total atomization energy, and heat of formation are 67.07, 117.55, and 0.35 kcal mol−1, respectively, at 298.15 K. © 1997 John Wiley & Sons, Inc. 相似文献
12.
Syed Mahmud Hasan 《Journal of polymer science. Part A, Polymer chemistry》1982,20(10):2969-2978
A study of the effects of ingredients on styrene emulsion polymerization kinetics showed that the purity of sodium dodecyl sulfate emulsifier affected the rate of polymerization (Rp) in the absence of added initiator. Below a critical concentration oxygen accelerated the Rp; above the critical concentration it inhibited the Rp. The effect of distilling styrene, compared to washing it with alkali to deinhibit, was minimal. Indications are that particulate dispersions of silica and titanium dioxide are encapsulated in situ by the growing polymer chains during styrene emulsion polymerization. 相似文献
13.
Zhen‐Yi Jiang Xiao‐Hong Xu Hai‐Shun Wu Fu‐Qiang Zhang Zhi‐Hao Jin 《International journal of quantum chemistry》2004,97(4):876-882
Geometric and electronic properties of CmN2 (m = 1–14) clusters have been investigated by density functional theory using the hybrid B3LYP functional and the 6‐311G(d) basis set. Harmonic frequencies for these clusters are given to aid in the characterization of the ground states. These results show that CmN2 (m = 1–14) clusters form linear structures with D∞h symmetry. Two N atoms favor to bond at ends in linear isomers. The chains with odd m have triplet ground states whereas the ones with even m have singlet ground states. The calculated HOMO–LUMO gaps and ionization potentials all show that the CmN2 (m = 1–14) clusters with even m are more stable than those with odd m, which is consistent with the observed even–odd alternation of the time‐of‐flight signal intensities. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004 相似文献
14.
Hans-Dieter Scharf Jrg Fleischhauer Hans Leismann Ingrid Ressler Wolf-gang Schleker Robert Weitz 《Angewandte Chemie (International ed. in English)》1979,18(9):652-662
The utilization of simple photochemical reactions for the storage of solar energy in the form of chemical energy in energy-rich products has often been considered in the further development and improvement of e. g. simple thermosolar techniques. The hitherto proposed criteria for the qualification of an abiotic photochemical system are, however, mostly of a qualitative nature, so a mutal comparison of the systems is not precise enough. In this article it is shown how a useful correlation on the basis of time-independent experimental data can be achieved and how, from the viewpoint of photochemistry, a comparative classification of known reactions is possible. The following reactions are compared: the [2 + 2]-photocycloadditions of norbornadiene, dimethyl 2,3-norbornadienedicarboxylate, and dicyclopentadienone, the photoisomerization of trans- to cis-diacetylindigo, the photodissociation of nitrosyl chloride as well as a photocatalytic redox reaction. The quantity of material required and storage efficiency are by far the most favorable in the case of trans-diacetylindigo. The main disadvantage of the latter however, is that the energy-rich cis-from rapidly reverts to the stable trans-form at elevated temperatures. 相似文献
15.
Stress crazing is studied in three forms of crystalline, isotactic polypropylene (PP): (1) smectic/nonspherulitic, (2) monoclinic/nonspherulitic, and (3) monoclinic/spherulitic PP. Optical and scanning electron microscopy as well as stress—strain measurements are used to characterize crazing behavior in these three forms as a function of temperature (?210 to 60°C) and of the gaseous environment (vacuum, He, N2, Ar, O2, and CO2). Forms 1 and 2 are found to craze much like an amorphous, glassy polymer in the temperature range between ?210 and ?20°C, irrespective of environment. The plastic crazing strain is large close to the glass-transition range (ca. ?20°C) of amorphous PP and in the neighborhood of the condensation temperature of the environmental gas. Near condensation, the gas acts as a crazing agent inasmuch as the stress necessary to promote crazing is lower in its presence than in vacuum. A gas is the more efficient as a crazing agent, the greater is its thermodynamic activity. Spherulitic PP (form 3) crazes in an entirely different manner from an amorphous, glassy polymer, showing that the presence of spherulites influences crazing behavior much more profoundly than the mere presence of a smectic or monoclinic crystal lattice. Below room temperature, crazes are generally restricted in length to a single spherulite, emanating from the center and going along radii perpendicular, within about 15°, to the direction of stress. They never go along spherulite boundaries. Gases near their condensation temperature act as crazing agents much as in nonspherulitic PP. Above room temperature the crazes are no longer related to the spherulite structure, being extremely long and perfectly perpendicular to the stress direction. Apparently the crystals are softened enough by thermally activated segmental motion to permit easy propagation of the craze. The morphology of the fracture surfaces and its dependence on temperature and environment is described and discussed. Concerning the action of gases as crazing agents it is argued that the gas is strongly absorbed at the craze tip, where stress concentration increases both the equilibrium gas solubility and the diffusion constant. Hence, a plasticized zone is formed having a decreased yield stress for plastic flow. This is considered to be the main mechanism by which the gas acts as a crazing agent. In addition, reduction of the surface energy of the polymer by the adsorbed gas eases the hole formation involved in crazing. 相似文献
16.
Graziano Guella Ines Mancini Helmut Zibrowius Francesco Pietra 《Helvetica chimica acta》1988,71(4):773-782
From the scleractinian coral Tubastraea sp. (Dendrophylliidae) collected at Palawan, Philippines, 3′-deimino-3′-oxoaplysinopsin ( 4 ) and 6-bromo-3′-deimino-3′-oxoaplysinopsin ( 6 ) are now isolated as 5:2 mixtures of (E/Z) stereoisomers. The 3′-deimino-2′,4′-bis(demethyl)-3′-oxoaplysinopsin ( 7 ) and 6-bromo-3′-demino-2′,4-bis(demethyl)-3′-oxoaplysinopsin ( 5 ) are isolated as 2:3 and 1:1 (E/Z) mixtures, respectively, from another dendrophylliid, Leptopsammia pruvoti, collected near Marseille, Mediterranean coast of France. Larger amounts of these and related compounds, needed for a full structural determination, are obtained by synthesis. Thus, condensations of indol-3-carboxaldehyde (9) or of its 6-bromo derivative 14 with hydantoin (15) , 3-methylhydantoin (11) , or 1,3dimethylhydantoin (10) give the prevalent natural aplysinopsins with high stereospecificity. The minor stereoisomers (Z)- 4 , (Z)- 6 , (E)- 7 , and (E)- 5 are obtained by (E/Z) photoisomerization under UV light of the condensation mixtures. The configuration is assigned from larger H? C(8)/C(5′) 1H, 13C couplings in the (E) than in the (Z) isomer, and, in the case of 4 and 6 , from NOE enhancement at Me? N(2′) on irradiation at H? C(8). The stereospecificity of the condensations is attributed to steric inhibition to planarity in the rate-limiting transition states, due to N(2′)/H? C(2) repulsion with (Z)- 4 and (Z)- 6 , or to C(5′)?O/H? C(2) repulsion with (E)–7 or (E)- 5 . As the aplysinopsins undergo (E/Z ) phostoisomerization also under the daylight conditions of the laboratory, their isomeric composition in nature can not be presently assessed. 相似文献
17.
Panchenko Yurii N. De Maré George R. Aroca Ricardo Bock Charles W. 《Structural chemistry》2000,11(2-3):121-140
Total geometry optimization and calculation of the force constants for all-transand t,T,t,C,t,T,tdeca-1,3,5,7,9-pentaene were carried out at the ab initio, HF/6-31G level. The HF/6-31G//HF/ 6-31G force fields were modified using empirical scale factors transferred from trans-buta-1,3-diene augmented by an additional scale factor for the central formal carbon-carbon double bond coordinates (determined previously for all-trans-hexa-1,3,5-triene). The total number of scale factors was seven. The vibrational problems for both decapentaenes were solved using the respective scaled HF/6-31G//HF/6-31G force field. Infrared intensities and Raman activities were calculated from the unscaled HF/6-31G//HF/6-31G force fields. Complete assignment of all the fundamental vibrational frequencies is given. Geometrical parameters, vibrational frequencies and force constants are compared with the corresponding values of buta-1,3-diene, hexa-1,3,5-triene and octa-1,3,5,7-tetraene. Regularities in the properties of this molecular series are discussed. Special attention is given to the possibility of using the vibrational spectra for detection of distortions from the regular trans structure of these oligoenes. 相似文献
18.
Dieter Seebach H. Michael Bürger Dietmer A. Plattner Reinhard Nesper Thomas Fssler 《Helvetica chimica acta》1993,76(7):2581-2601
The triolide of (R)-3-hydroxybutanoic acid ((R,R,R,))-3,7,11-trimethyl-2,6,10-trioxadodecane-1,5,9-trione; ( 1 ), readily available from the corresponding biopolymer P(3-HB) in one step, forms crystalline complexes with alkali and alkaline earth salts. The X-ray crystal structures of three such complexes, (3 NaSCN)·4 1 ( 2 ), (2 KSCN)·2 1 · H2O ( 3 ), and (2) Ba(SCN)2 · 2 1 · 2 H2O · THF ( 4 ), have been determined and are compared. The triolide is found in these structures (i) as a free molecule, making no contacts with a cation (clathrate-type inclusion), (ii) as a monodentate ligand coordinated to a single ion with one carbonyl O-atom only, (iii) as a chelator, forming an eight-membered ring, with two carbonyl O-atoms attached to the same ion, (iv) as a linker, using two carbonyl O-atoms to bind to the two metals of an ion-X-ion unit (ten-membered ring), and (v), in a crown-ester complex, in which an ion is sitting on the three unidirectional C?O groups of a triolide molecule (Figs. 1–3). The crystal packing is such that there are columns along certain axes in the centers of which the cations are surrounded by counterions and triolide molecules, with the non-polar parts of 1 on the outside (Fig. 4). In the complexes 2–4 , the triolide assumes conformations which are slightly distorted, with the carbonyl O-atoms moved closer together, as compared to the ‘free’ triolide 1 (Fig. 5). These observed features are compatible with the view that oligo (3-HB) may be involved in the formation of Ca polyphosphate ion channels through cell membranes. A comparison is also made between the triolide structure in 1–4 and in enterobactin, a super Fe chelator (Fig. 5). To better understand the binding between the Na ion and the triolide carbonyl O-atoms in the crown-ester complex, we have applied electron-localization function (ELF) calculations with the data set of structure 2 , and we have produced ELF representations of ethane, ethene, and methyl acetate (Figs. 6–9). It turns out that this theoretical method leads to electron-localization patterns which are in astounding agreement with qualitative bonding models of organic chemists, such as the ‘double bond character of the CO? OR single bond’ or the ‘hyperconjugative n → σ* interactions between lone pairs on the O-atoms and neighbouring σ-bonds’ in ester groups (Fig. 8). The noncovalent, dipole/pole-type character of bonding between Na+ and the triolide carbonyl O-atoms in the crown-ester complex (the Na? O?C plane is roughly perpendicular to the O? C?O plane) is confirmed by the ELF calculation; other bonding features such as the C?N bond in the NaSCN complex 2 are also included in the discussion (Fig. 9). 相似文献
19.
W. J. Feast J. Put F. C. De Schryver F. C. Compernolle 《Journal of mass spectrometry : JMS》1970,3(4):507-517
The mass spectral fragmentation of some maleimides, isomaleimides, bis-maleimides, bis-isomaleimides and diazatetracyclotetraones (intramolecular photocyclization products of bis-maleimides) have been investigated. The elimination of carbon dioxide from the molecular ions of these compounds is not generally an important process. Fragment ions arising from the transfer of one or more hydrogen atoms from the eliminated to the charge retaining moiety (and vice versa) are prevalent and the variation in fragment ion intensity with changes in structure is consistent with the mechanisms of the analogous fragmentations of succinimides established by Djerassi's group. The apparently unusual fragmentations of the diazatetracyclotetraones may be rationalized on the basis that the molecular ion consists of three or more different species. 相似文献
20.
Synthesis, Characterization and Thermal Decomposition of the Pyridine Adducts of Co, Ni, Cu and Zn Sulfate 总被引:1,自引:0,他引:1
V. Jordanovska P. Naumov B. Boyanov R. Trojko 《Journal of Thermal Analysis and Calorimetry》2000,59(3):859-868
Pyridine adducts of Co, Ni, Cu and Zn sulfate were obtained by refluxing the corresponding sulfate with pyridine in chloroform.
The compounds were characterized by elemental analysis, X-ray powder diffraction and FTIR spectroscopy. The thermal decompositions
(TG/DTG/DTA) of the complexes in the interval 20–1000°C were also studied.
The elemental and thermal analysis results revealed that the formulae of the complexes are M2(SO4)2
xC5H5NyH2O, where x=2, 3, 2 and 1 and y=6, 4, 6 and 4 for the Co, Ni, Cu and Zn compound, respectively. The complexes were not found to be isostructural, but certain
structural similarities were observed between the Zn and Co compounds. Although the thermal decomposition pathways of the
various compounds were quite different and each consisted of several steps, in all cases the dehydration preceded the depyridination.
Metal oxide was always obtained as final product.
The spectral data are discussed with regard to the thermal behaviour. Appreciably stronghydrogen-bonding and pronounced structural
differences relating to the sulfate ions were presumed for the Cu compound.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献