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1.
Georgy G. Gospodinov Miluvka G. Stancheva 《Monatshefte für Chemie / Chemical Monthly》2002,133(11):1381-1386
Summary. The solubility isotherm of the system Lu2O3–SeO2–H2O was studied at 100°C. The compounds of the three-component system were identified by Schreinemakers’ method and chemical, derivatograph and X-ray phase analyses after separation in the pure state: Lu2(SeO3)3·4H2O and LuH(SeO3)2·2H2O.
Received February 27, 2002; accepted (revised) April 26, 2002 相似文献
2.
L. T. Vlaev Svetlana D. Genieva Velyana G. Georgieva 《Journal of Thermal Analysis and Calorimetry》2006,86(2):449-456
The solubility of NiSeO3–SeO2–H2O
system in the temperature region 298–573 K was studied. The compounds
of the three-component system were identified by the Schreinemakers’
method. The phase diagram of nickel(II) selenites was drawn and the crystallization
fields for the different phases were determined. Depending on the conditions
for hydrothermal synthesis, NiSeO3·2H2O,
α-NiSeO3·1/3H2O,
β-NiSeO3·1/3H2O,
NiSeO3 and NiSe2O5
were obtained. The different phases were proved and characterized by chemical,
powder X-ray diffraction and thermal analyses as well as IR spectroscopy. 相似文献
3.
Wenshen C. Yi L. Chuanpei Z. Songsheng Q. 《Journal of Thermal Analysis and Calorimetry》2001,66(2):463-468
The solid-state coordination reaction: Nd(NO3)3·6H2O(s)+4Ala(s) → Nd(Ala)4(NO3)3·H2O(s)+5H2O(l) and Er(NO3)3·6H2O(s)+4Ala(s) → Er(Ala)4(NO3)3·H2O(s)+5H2O(l) have been studied by classical solution calorimetry. The molar dissolution enthalpies of the reactants and the products
in 2 mol L–1 HCl solvent of
these two solid-solid coordination reactions have been measured using a calorimeter. From the results and other auxiliary
quantities, the standard molar formation enthalpies of [Nd(Ala)4(NO3)3·H2O, s, 298.2 K] and[Er(Ala)4(NO3)3·H2O, s,298.2 K] at 298.2 K have been determined to be Δf
H
m
0 [Nd(Ala)4(NO3)3·H2O,s, 298.2 K]=–3867.2 kJ mol–1, and Δf
H
m
0 [Er(Ala)4(NO3)3·H2O, s, 298.2 K]=–3821.5 kJ mol–1.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
4.
The solubility of the system CdO-SeO2-H2O was studied at 25 and 100°C. The fields of crystallization of α-CdSeO3, 3CdSeO3·H2SeO3 and CdSeO3·SeO2 were established at 25°C. At 100°C crystallize α-CdSeO3, 3CdSeO3·SeO2, 2CdSeO3·SeO2 and CdSeO3·SeO2. The compounds obtained were identified by means of chemical, X-ray and crystal-optical analysis. The mechanism of thermal
dissociation of α-CdSeO3, 3CdSeO3·H2SeO3 and CdSeO3·SeO2 was studied.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
5.
A. P. Tyutyunnik V. N. Krasil’nikov I. F. Berger V. G. Zubkov L. A. Perelyaeva I. V. Baklanova 《Russian Journal of Inorganic Chemistry》2011,56(8):1168-1177
The vanadium(V) complexes K[VO2(SeO4)(H2O)] and K[VO2(SeO4)(H2O)2] · H2O were synthesized using original procedures; their physicochemical properties were studied, and the crystal structure was
determined on the basis of X-ray diffraction and neutron diffraction data. The structure of K[VO2(SeO4)(H2O)2] · H2O is composed of VO6 octahedra connected to form infinite chains by bridging SeO4 tetrahedra. Each VO6 tetrahedron has short terminal V-O bonds forming the bent dioxovanadium group VO2+ The unit cell parameters of K[VO2(SeO4)(H2O)2] · H2O are a = 6.4045(1) ?, b = 9.9721(2) ?, c = 6.6104(1) ?, β = 107.183(1)°, V = 403.34 ?3, Z = 2, monoclinic system, space group P21. The complex K[VO2(SeO4)(H2O)] forms a two-dimensional layered structure composed of highly distorted VO6 octahedra having two short terminal V-O bonds and SeO4 groups coordinated simultaneously by three vanadium atoms. This compound crystallizes in the monoclinic system (space group
P21/c): a = 7.3783(1) ?, b = 10.5550(2) ?, c = 10.3460(2) ?, β = 131.625(1)°, V = 602.894(5) ?3, Z= 4. The vibrational spectra of the studied compounds are fully consistent with their structural features. 相似文献
6.
The thermal dehydration-decomposition of Ln2(SeO4)3·nH2O (wheren=12 forLn=Pr, Nd andn=8 forLn=Sm) and PrxLn2−x(SeO4)3·nH2O (wheren=12 forx=1.0 andLn=Nd;n=8 forx=0.2 and 1.0 in case ofLn=Sm) have been reported.
Zusammenfassung Die thermische Dehydratation-Zersetzung von Ln2(SeO4)3·nH2O (mitn=12 fürLn=Pr, Nd undn=8 fürLn=Sm) und PrxLn2−x(SeO4)3·nH2O (mitn=12 fürx=1.0 undLn=Nd;n=8 fürx=0.2 und 1.0 in Falle vonLn=Sm) wurde beschrieben.相似文献
7.
Todora Ojkova Donka Stoilova Dimitar Barkov 《Monatshefte für Chemie / Chemical Monthly》2000,14(1):1019-1023
The solubilities in the systems Rb2SeO4=ZnSeO4=H2O and Cs2SeO4=ZnSeO4=H2O at 25°C were studied by the method of isothermal decrease of supersaturation. Comparatively wide crystallization fields
of the double salts Rb2Zn(SeO4)2ċ6H2O and Cs2Zn(SeO4)2ċ6H2O are observed in the solubility diagrams. The double salts form monoclinic crystals which are isostructural with those of
the corresponding rubidium and cesium zinc sulfate hexahydrates. TG and TDA measurements indicate that the double salts lose
their crystallization water in one step in the temperature intervals of 50–160°C (rubidium salt) and 70–150°C (cesium salt). 相似文献
8.
Hydrothermal Synthesis and Crystal Structures of Na2Be3(SeO3)4·H2O and Cs2[Mg(H2O)6]3(SeO3)4
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The selenites, Na2Be3(SeO3)4 · H2O and Cs2[Mg(H2O)6]3(SeO3)4, were synthesized under hydrothermal conditions. The crystal structures of Na2Be3(SeO3)4 · H2O and Cs2[Mg(H2O)6]3(SeO3)4 were determined by single‐crystal X‐ray diffractions. Na2Be3(SeO3)4 · H2O crystallizes in the triclinic space group P1 (no. 2) with unit cell parameters a = 4.8493(9), b = 12.013(2), c = 12.077(2) Å, and Z = 2, whereas Cs2[Mg(H2O)6]3(SeO3)4 crystallizes in the monoclinic space group C2/m (no. 12) with lattice cell parameters a = 12.596(6), b = 7.297(4), c = 16.914(8) Å, and Z = 2. Na2Be3(SeO3)4 · H2O features a three‐dimensional open framework structure formed by BeO4 tetrahedra and SeO3 trigonal pyramids. Na cations and H2O molecules are located in different tunnels. Cs2[Mg(H2O)6]3(SeO3)4 has a structure composed of isolated [Mg(H2O)6] octahedra and SeO3 trigonal pyramids interacted by hydrogen bonds, and Cs cations are resided in‐between. Both compounds were characterized by thermogravimetric analysis and FT‐IR spectroscopy. 相似文献
9.
Todora Ojkova Donka Stoilova Dimitar Barkov 《Monatshefte für Chemie / Chemical Monthly》2000,131(10):1019-1023
Summary. The solubilities in the systems Rb2SeO4=ZnSeO4=H2O and Cs2SeO4=ZnSeO4=H2O at 25°C were studied by the method of isothermal decrease of supersaturation. Comparatively wide crystallization fields
of the double salts Rb2Zn(SeO4)2ċ6H2O and Cs2Zn(SeO4)2ċ6H2O are observed in the solubility diagrams. The double salts form monoclinic crystals which are isostructural with those of
the corresponding rubidium and cesium zinc sulfate hexahydrates. TG and TDA measurements indicate that the double salts lose
their crystallization water in one step in the temperature intervals of 50–160°C (rubidium salt) and 70–150°C (cesium salt).
Received March 14, 2000. Accepted (revised) June 5, 2000 相似文献
10.
Magnetic susceptibility investigations have been carried out on a family of the tetra-transition-metal sandwiched Weakley-type
germanotungstates Na11H[Co4(H2O)2(α-GeW9O34)2]·31H2O (1), (C6N2H18)4[Co(H2O)6]H2[Co4(H2O)2(α-GeW9O34)2]·5.5H2O (2) and Na(H2O)2(C6N2H18)4.75H1.5[Ni4(H2O)2(α-GeW9O34)2]·1.5H2O (3) with the intention of studying the magnetic exchange properties of the rhomb-like four transition-metal ions in the central
belt. The Co–Co and Ni–Ni ferromagnetic exchange interactions are dominant in the rhomb-like M4O16 units in 1–3. Furthermore, magnetic susceptibility measurements also reveal that the magnetic coupling constant J is a sensitive parameter that is closely realted to the M–O–M angles and M···M separations in the rhomb-like magnetic core.
Variable-temperature ac susceptibilities exhibit that magnetic properties of 2 and 3 are related to the spin glassy behaviors. 相似文献
11.
Wen-Kui Dong Jun-Feng Tong Yin-Xia Sun Jian-Chao Wu Jian Yao Shang-Sheng Gong 《Transition Metal Chemistry》2010,35(4):419-426
Two new mono- and dinuclear Cu(II) complexes, namely [CuL1]·0.5H2O (1) and [(Cu2(L2)2)(DMF)]·0.5DMF (2) (H2L1 = 1,2-bis{[(Z)-(3-methyl-5-oxo-1-phenyl-1H-pyrazolidin-4(4H)-yl)(phenyl)]methylene-aminooxy}ethane; H2L2 = 1,3-bis{[(Z)-(3-methyl-5-oxo-1-phenyl-1H-pyrazolidin-4(4H)-yl)(phenyl)] methyleneaminooxy}propane), have been synthesized and characterized by X-ray crystallography. The unit cell
of complex 1 contains two crystallographically independent but chemically identical [CuL1] molecules and one crystalline water molecule, showing a slightly distorted square-planar coordination geometry and forming
a wave-like pattern running along the a-axis via hydrogen bonding and π···π stacking interactions. Complex 2 has a dinuclear structure, comprising two Cu(II) atoms, two completely deprotonated phenolate bisoxime (L2)2− moieties (in the form of enol), and both coordinated and hemi-crystalline DMF molecules. Complex 2 has square-planar and square-pyramidal geometries around the two copper centers, whose basic coordination planes are almost
perpendicular and form an infinite three-dimensional supramolecular network structure involving intermolecular C–H···N, C–H···O,
and C–H···π(Ph) hydrogen bonding and π···π stacking interactions of neighboring pyrazole rings. 相似文献
12.
Revathy Rajagopal Vishnu R. Ajgaonkar 《Monatshefte für Chemie / Chemical Monthly》2002,39(3):1387-1395
Double rare earth monomethylammonium selenates of the general formula CH3NH3 Ln (SeO4)2·5H2O (Ln = Sm, Eu, Gd, Tb, Ho, Y) were synthesized and characterized using X-ray powder diffraction and infrared spectroscopy. The thermal decomposition of the compounds were investigated using TG, DTG, and DTA techniques. 相似文献
13.
P. S. Berdonosov P. Schmidt O. A. Dityat'yev V. A. Dolgikh P. Lightfoot Michael Ruck 《无机化学与普通化学杂志》2004,630(10):1395-1400
Pale pink crystals of Nd2(SeO3)2(SeO4) · 2H2O were synthesized under hydrothermal conditions from H2SeO3 and Nd2O3 at about 200 °C. X‐ray diffraction on powder and single‐crystals revealed that the compound crystallizes with the monoclinic space group C 2/c (a = 12.276(1) Å, b = 7.0783(5) Å, c = 13.329(1) Å, β = 104.276(7)°). The crystal structure of Nd2(SeO3)2(SeO4) · 2H2O is an ordered variant of the corresponding erbium compound. Eight oxygen atoms coordinate the NdIII atom in the shape of a bi‐capped trigonal prism. The oxygen atoms are part of pyramidal (SeIVO3)2? groups, (SeVIO4)2? tetrahedra and water molecules. The [NdO8] polyhedra share edges to form chains oriented along [010]. The selenate ions link these chains into layers parallel to (001). The layers are interconnected by the selenite ions into a three‐dimensional framework. The dehydration of Nd2(SeO3)2(SeO4) · 2H2O starts at 260 °C. The thermal decomposition into Nd2SeO5, SeO2 and O2 at 680 °C is followed by further loss of SeO2 leaving cubic Nd2O3. 相似文献
14.
Y. Y. Di Z. C. Tan L. W. Li S. L. Gao L. X. Sun 《Journal of Thermal Analysis and Calorimetry》2007,87(2):545-551
Low-temperature heat capacities of a solid
complex Zn(Val)SO4·H2O(s) were measured by a precision automated adiabatic
calorimeter over the temperature range between 78 and 373 K. The initial dehydration
temperature of the coordination compound was determined to be, T
D=327.05
K, by analysis of the heat-capacity curve. The experimental values of molar
heat capacities were fitted to a polynomial equation of heat capacities (C
p,m) with the reduced temperatures
(x), [x=f (T)], by least
square method. The polynomial fitted values of the molar heat capacities and
fundamental thermodynamic functions of the complex relative to the standard
reference temperature 298.15 K were given with the interval of 5 K.
Enthalpies of dissolution of the [ZnSO4·7H2O(s)+Val(s)] (Δsol
H
m,l
0)
and the Zn(Val)SO4·H2O(s) (Δsol
H
m,2
0) in 100.00 mL of 2 mol dm–3 HCl(aq) at T=298.15
K were determined to be, Δsol
H
m,l
0=(94.588±0.025) kJ mol–1 and Δsol
H
m,2
0=–(46.118±0.055)
kJ mol–1, by means of a homemade isoperibol
solution–reaction calorimeter. The standard molar enthalpy of formation
of the compound was determined as: Δf
H
m
0
(Zn(Val)SO4·H2O(s), 298.15 K)=–(1850.97±1.92) kJ mol–1,
from the enthalpies of dissolution and other auxiliary thermodynamic data
through a Hess thermochemical cycle. Furthermore, the reliability of the Hess
thermochemical cycle was verified by comparing UV/Vis spectra and the refractive
indexes of solution A (from dissolution of the [ZnSO4·7H2O(s)+Val(s)] mixture
in 2 mol dm–3 hydrochloric acid) and solution
A’ (from dissolution of the complex Zn(Val)SO4·H2O(s) in 2 mol dm–3
hydrochloric acid). 相似文献
15.
The complexes of 4-chloro-2-methoxybenzoic acid anion with Mn2+,
Co2+, Ni2+, Cu2+
and Zn2+ were obtained as polycrystalline solids
with general formula M(C8H6ClO3)2·nH2O and colours typical for M(II) ions (Mn – slightly pink, Co –
pink, Ni – slightly green, Cu – turquoise and Zn – white).
The results of elemental, thermal and spectral analyses suggest that compounds
of Mn(II), Cu(II) and Zn(II) are tetrahydrates whereas those of Co(II) and
Ni(II) are pentahydrates. The carboxylate groups in these complexes are monodentate.
The hydrates of 4-chloro-2-methoxybenzoates of Mn(II), Co(II), Ni(II), Cu(II)
and Zn(II) heated in air to 1273 K are dehydrated in one step in the range
of 323–411 K and form anhydrous salts which next in the range of 433–1212
K are decomposed to the following oxides: Mn3O4,
CoO, NiO and ZnO. The final products of decomposition of Cu(II) complex are
CuO and Cu. The solubility value in water at 293 K for all complexes is in
the order of 10–3 mol dm–3.
The plots of χM
vs.
temperature of 4-chloro-2-methoxybenzoates of Mn(II), Co(II), Ni(II) and Cu(II)
follow the Curie–Weiss law. The magnetic moment values of Mn2+,
Co2+, Ni2+ and Cu2+
ions in these complexes were determined in the range of 76−303 K and
they change from: 5.88–6.04 μB for Mn(C8H6ClO3)2·4H2O, 3.96–4.75
μB for Co(C8H6ClO3)2·5H2O, 2.32–3.02 μB for Ni(C8H6ClO3)2·5H2O and 1.77–1.94
μB for Cu(C8H6ClO3)2·4H2O. 相似文献
16.
H. López-González M. Jiménez-Reyes M. Solache-Ríos A. Rojas-Hernández 《Journal of Radioanalytical and Nuclear Chemistry》2007,274(1):103-108
Solubility product (Lu(OH)3(s)⇆Lu3++3OH−) and first hydrolysis (Lu3++H2O⇆Lu(OH)2++H+) constants were determined for an initial lutetium concentration range from 3.72·10−5 mol·dm−3 to 2.09·10−3 mol·dm−3. Measurements were made in 2 mol·dm−3 NaClO4 ionic strength, under CO2-free conditions and temperature was controlled at 303 K. Solubility diagrams (pLuaq vs. pC
H) were determined by means of a radiochemical method using 177Lu. The pC
H for the beginning of precipitation and solubility product constant were determined from these diagrams and both the first
hydrolysis and solubility product constants were calculated by fitting the diagrams to the solubility equation. The pC
H values of precipitation increases inversely to [Lu3+]initial and the values for the first hydrolysis and solubility product constants were log10
β*
Lu,H
= −7.92±0.07 and log10
K*sp,Lu(OH)3 = −23.37±0.14. Individual solubility values for pC
H range between the beginning of precipitation and 8.5 were S
Lu3+ = 3.5·10−7 mol·dm−3, S
Lu(OH)2+ = 6.2·10−7 mol·dm−3, and then total solubility was 9.7·10−7 mol·dm−3. 相似文献
17.
The structure of tetraaqua-bis(nitrato-O,O′)-(1,10-phenanthroline-N,N′)-lanthanum(III) 1,3,5,7-tetraazatricyclo[3.3.1.13,7]decane nitrate dihydrate, [La(NO3)2 · phen · (H2O)4]+ · hmt · NO
3
−
· 2H2O, is presented. The lanthanum ion exhibits tenfold coordination and the polyhedron can be described as tetradecahedron. The
complex cations, nitrate ions, water and hexamethylenetetramine molecules are assembled via hydrogen bonds, H–π rings and π–π stacking interactions into 3D supramolecular network. The bond strength of coordination sphere was calculated by means of
the bond-valence method. The influence of La:phen stoichiometry and additional ligand on the changes of lanthanum(III) coordination
sphere geometry in ten-coordinated complexes with 1,10-phenanthroline was discussed. The infrared spectrum of structure optimised
by means of quantum mechanical calculations was analysed and compared with measured one. The obtained compound was characterised
by thermogravimetric analysis in conjunction with evolved gases in the air atmosphere. 相似文献
18.
Banjong Boonchom 《Journal of Thermal Analysis and Calorimetry》2009,98(3):863-871
The thermal decomposition of magnesium hydrogen phosphate trihydrate MgHPO4 · 3H2O was investigated in air atmosphere using TG-DTG-DTA. MgHPO4 · 3H2O decomposes in a single step and its final decomposition product (Mg2P2O7) was obtained. The activation energies of the decomposition step of MgHPO4 · 3H2O were calculated through the isoconversional methods of the Ozawa, Kissinger–Akahira–Sunose (KAS) and Iterative equation,
and the possible conversion function has been estimated through the Coats and Redfern integral equation. The activation energies
calculated for the decomposition reaction by different techniques and methods were found to be consistent. The better kinetic
model of the decomposition reaction for MgHPO4 · 3H2O is the F
1/3 model as a simple n-order reaction of “chemical process or mechanism no-invoking equation”. The thermodynamic functions (ΔH*, ΔG* and ΔS*) of the decomposition reaction are calculated by the activated complex theory and indicate that the process is non-spontaneous
without connecting with the introduction of heat. 相似文献
19.
Saturating solid phases, Ce2(SO4)3·hH2O, with hydrate numbers h equal to 12, 9, 8, 5, 4 and 2, have been identified by critical evaluation of the solubility data
in the system Ce2(SO4)3—H2O over the temperature range 273–373 K. The results are compared with the respective TG—DTA—DSC and X-ray data. The solubility
smoothing equations, transition points and solution enthalpy estimators of the identified hydrates are given. The stable equilibrium
solid phases are concluded to be only Ce2(SO4)3·9H2O at 273–310 K, Ce2(SO4)3·4H2O at 310–367 K and Ce2(SO4)3·2H2O at 367–373 K. Divergencies of up to 185% in the reported solubility data are mainly due to a variety of metastable equilibria
involved in the close crystallization fields, and incorrect assignments of the saturating solid phases. Since a similar variety
of the hydrate numbers exists for the analogous La(III) system, it most probably also occurs for the corresponding Pu(III),
Np(III) and U(III) systems.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
20.
In poly[[diaquaoxido[μ3‐trioxidoselenato(2−)]vanadium(IV)] hemihydrate], {[VO(SeO3)(H2O)2]·0.5H2O}n, the octahedral V(H2O)2O4 and pyramidal SeO3 building units are linked by V—O—Se bonds to generate ladder‐like chains propagating along the [010] direction. A network of O—H...O hydrogen bonds helps to consolidate the structure. The O atom of the uncoordinated water molecule lies on a crystallographic twofold axis. The title compound has a similar structure to those of the reported phases [VO(OH)(H2O)(SeO3)]4·2H2O and VO(H2O)2(HPO4)·2H2O. 相似文献