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1.
Summary. The geometries and total energies of several T-shaped platinum(II) complexes of the type (H3P)PtXY (X, Y=Cl, CH3, SiH3, Si(OH)3) were calculated by ab-initio methods. In the most stable isomer, the ligand with the smallest trans influence is trans to the PH3 ligand. The trans influence increases in the order Cl<CH3<SiH3<Si(OH)3.
Corresponding author. E-mail: uschuber@mail.2serv.tuwien.ac.at
Received October 14, 2002; accepted October 14, 2002
Published online May 2, 2003 相似文献
2.
Summary. Quinoxalinium dichromate (QxDC) oxidizes benzyl alcohol and substituted benzyl alcohols smoothly in dimethyl sulfoxide (DMSO) and in the presence of acid to the corresponding aldehydes. The reaction has unit dependence on each of the alcohol, QxDC, and acid concentrations. Electron-releasing substituents accelerate the reaction, whereas electron-withdrawing groups retard the reaction, and the rate data obey Hammetts relationship. The reaction constant was –1.09±0.01 at 303K. Oxidation of ,-dideuteriobenzyl alcohol indicated the presence of a substantial primary kinetic isotope effect (kH/kD=6.78 at 303K). The reaction failed to induce the polymerization of acrylonitrile. The rates of oxidation were determined at different temperatures and the activation parameters were evaluated. The analysis of the dependence of the kinetic isotope effect on temperature indicated that the reaction involves a symmetrical cyclic transition state. A suitable mechanism is proposed. 相似文献
3.
Iveta Kmentová Battsengel Gotov Vladimír Gajda Štefan Toma 《Monatshefte für Chemie / Chemical Monthly》2003,134(4):545-549
Summary. The Sonogashira reaction of iodobenzene with phenylacetylene in several room temperature ionic liquids was studied. A regeneration of the
catalytical system immobilized in 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6) has been also investigated. The reactivity of different iodoarenes with terminal alkynes in [bmim]PF6 was studied as well.
Corresponding author. E-mail: toma@fns.uniba.sk
Received September 2, 2002; accepted September 9, 2002 相似文献
4.
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
5.
Summary. Several compounds may exist in LnCl3–MCl mixtures. Those corresponding to the M
2
LnCl5 and MLn
2Cl7 stoichiometries are formed in a few systems only, with diverse stability strongly dependent on both the corresponding lanthanide
and alkali metal. On the other hand, M
3
LnCl6 that occur in most systems have a far larger stability range and melt congruently. These latter compounds were investigated
in the present work by differential scanning calorimetry and electrical conductivity measurements. The thermodynamic and transport
properties were correlated to structural features and related to the mechanism of compound formation.
Corresponding author. E-mail: Marcelle.Gaune-Escard@polytech.univ-mrs.fr
Received October 2, 2002; accepted November 6, 2002
Published online April 24, 2003
RID="a"
ID="a" This paper is dedicated to Professor H. Gamsj?ger on the occasion of his birthday 相似文献
6.
Marek Burian Ladislav Omelka Silvie Ondrášová Vlasta Brezová 《Monatshefte für Chemie / Chemical Monthly》2003,134(4):501-508
Summary. Several N-phenyl substituted 1,4- and 1,2-phenylenediamines were oxidized using radicals and 3-chloroperbenzoic acid. EPR spectroscopy confirmed the generation of nitroxide radicals originating from the
oxidation of the bridging -NH-group. No radical products suggesting the simultaneous reaction with the NH2-group were observed. Only in the case of 1,4-phenylenediamine, a low concentration of nitroxide radical H–NO–C6H4–NH2 was obtained. In o-aminodiphenylnitroxide the steric effect of the NH2-group causes a partially asymmetrical spin density distribution in both phenyl rings.
Corresponding author. E-mail: omelka@fch.vutbr.cz
Received September 30, 2002; accepted October 4, 2002 相似文献
7.
Samih A. Halawy 《Monatshefte für Chemie / Chemical Monthly》2003,134(3):371-380
Summary. Unpromoted cobalt molybdate was prepared from Co(NO3)2·6H2O and (NH4)6Mo7O24·4H2O, then calcined between 350 and 600°C for 5 h. K2O (10 w%), as a promoter, was added to the calcined sample at 350°C from two different sources (i.e. KOH and KNO3) and was subjected to further calcination at 350°C for 5 h. The catalytic activity of unpromoted catalysts towards the vapour
phase decomposition of CH3COOH was greatly influenced by the increase in the calcination temperature. This is attributed to the diminution of both S
BET and their dual acidic–basic characters. The promoted sample from the KOH source was found to be the most active of the catalysts
studied. This is due to its high population of both acidic–basic surface sites and the formation of two new phases. XRD and
FTIR analyses of the used catalysts, after the decomposition reaction of acetic acid, showed a remarkable change in its structure
compared with the parent samples.
E-mail: shalawy99@yahoo.com
Received May 8, 2002; accepted (revised) July 9, 2002 相似文献
8.
Lyudmila V. Chernykh Jitka Eysseltova Mikhail Y. Skripkin 《Monatshefte für Chemie / Chemical Monthly》2003,134(5):751-761
Summary. Solubility isotherms in the CuBr2−MBr−H2O (M
+ = Li+, Na+, Cs+) systems at 298.15 K were measured. The results together with other available literature data for copper chloride and bromide
systems were treated by hydration analysis, and comparative discussion of ionic processes taking place in the respective saturated
solutions was performed.
Corresponding author. E-mail: jitka@prfdec.natur.cuni.cz
Received August 6, 2002; accepted (revised) November 29, 2002
Published online April 3, 2003 相似文献
9.
Arno F. Stassen Eugenia Martínez Ferrero Carlos Giménez-Saiz Eugenio Coronado Jaap G. Haasnoot Jan Reedijk 《Monatshefte für Chemie / Chemical Monthly》2003,134(2):255-264
Summary. The synthesis, crystal structure and physical properties of the complex obtained from the reaction between the polyoxometalate
anion [PMo12O40]3−, copper(II) and the ligand 1-(2-chloroethyl)tetrazole (teec) are described. This compound has been synthesized as a model for designing materials containing both magnetic polyoxometalate
anions and iron(II) spin-crossover cations.
The compound, with formula [Cu(teec)5]2[Cu(teec)6][PMo12O40]2·2H2O, consists of alternating layers of polyoxometalates and cationic complexes. Both, five and six coordinated Cu(II) ions are
present, each positioned in different layers. Despite these layers having a similar width, the layer of pentacoordinated Cu(II)
ions contains twice as many cationic complexes as the layer of hexacoordinated Cu(II) ions. This unusual coexistence of complexes
with different coordination number is most likely caused by the steric hindrance induced by the bulky polyoxometalates in
the layer of pentacoordinated Cu(II) which prevents the presence of a sixth teec ligand.
Corresponding author. E-mail: haasnoot@chem.leidenuniv.nl
Received June 5, 2002; accepted June 12, 2002 相似文献
10.
Summary. A series of 6- and 7-substituted derivatives of 1,3-diaminoisoquinoline were synthesized by the reaction of N,N-diethylarylacetamides with POCl3 and then with N,N-dimethylcyanamide. The products were identified by means of spectroscopic methods and their pK
a
dissociation constants were determined.
Corresponding author. E-mail: kudelkoa@zeus.polsl.gliwice.pl
Received July 7, 2002; accepted July 22, 2002 相似文献
11.
Revathy Rajagopal Vishnu R. Ajgaonkar 《Monatshefte für Chemie / Chemical Monthly》2002,133(11):1387-1395
Summary. 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.
Corresponding author. E-mail: vrajgaonkar@yahoo.com, vrajgaonkar@mail.mu.ac.in
Received November 5, 2001. Accepted (revised) March 6, 2002 相似文献
12.
Muhammad A. Motin Tapan K. Biswas Entazul M. Huque 《Monatshefte für Chemie / Chemical Monthly》2003,134(4):475-487
Summary. Density and viscosity of NaNO3 and KNO3 in aqueous and in H2O-urea solutions were determined as a function of electrolyte concentrations at 308, 313, 318, 323, and 328 K, respectively.
The apparent molal volume (φ
v
) of the electrolytes were found to be linear functions of the square root of the solute molality (b). The φ
v
and data were fitted to the Masson equation [1] by the least square method to obtain the apparent molar volume at infinite dilution (φ
v
^), which is practically equal to the partial molar volume . The viscosity coefficients A and B were calculated on the basis of the viscosity of the solutions and the solvent concerned using the Jones–Dole [2] equation. The activation parameters for viscous flow (ΔG
≠, ΔS
≠, and ΔH
≠) were calculated according to Eyring [3]. The values of for the two systems were also calculated from B-coefficient data. The results were found to be of opposite nature in the two electrolyte systems. Where sodium nitrate showed
structure making behaviour both in aqueous and in H2O-urea solutions, KNO3 showed structure breaking behaviour in aqueous solutions and structure making behaviour in 5 molal H2O-urea solutions in the studied temperature range. The behaviour of these two electrolytes in aqueous binary and in aqueous-urea
ternary systems are discussed in terms of charge, size, and hydrogen bonding effects.
Corresponding author. E-mail: chemistry_ru@yahoo.com
Received January 24, 2002; accepted (revised) April 5, 2002 相似文献
13.
Ludmila úrková Renáta Kucsera Róbert Gyepes Michal Sivák 《Monatshefte für Chemie / Chemical Monthly》2003,134(8):1071-1079
Summary. Two novel compounds, [Co(phen)3]2V4O12·phen·22H2O (1) and [Ni(phen)3]2 V4O12·phen·22H2O (2), were prepared from KVO3–1,10-phenanthroline (phen)–Co(NO3)2, resp. NiCl2–H2O reaction systems. The compounds 1 and 2 are isomorphous and crystallize in triclinic system, space group P-1. Their crystal structures are formed by two types of layers parallel to 001: a cationic one consisting of [MII(phen)3]2+ ions and an anionic one containing the cyclic V4O12
4– anions. The solvate phenanthroline and crystal water molecules are located in the cationic and anionic layers, respectively. The IR spectra of 1 and 2 are consistent with the presence of the cyclic V4O12
4– anions in the complexes.Received November 13, 2002; accepted (revised) February 3, 2003
Published online June 2, 2003 相似文献
14.
Summary. Single crystals of sodium dithiophosphate undecahydrate (Na3PO2S2 · 11H2O) and sodium trithiophosphate undecahydrate (Na3POS3 · 11H2O) were grown from aqueous solution. The crystal structures of Na3PO2S2 · 11H2O (P212121; a = 1248.1(1), b = 945.2(1), c = 1383.1(1) pm; R
1 = 0.0202, wR
2 = 0.0502) and Na3POS3 · 11H2O (Pna21; a = 1262.0(2), b = 947.6(2), c = 1431.5(2) pm; R
1 = 0.0720, wR
2 = 0.1371) are related to each other in a sense that all constituting units are arranged in similar positions and with similar
orientations. The geometries of the anions were determined with high accuracy; thus, the structural parameters of the POS3−
3 anion were measured for the first time.
Received September 25, 2001. Accepted January 21, 2002 相似文献
15.
Ulrich Englich Ingo Prass Karin Ruhlandt-Senge Thorsten Schollmeier Frank Uhlig 《Monatshefte für Chemie / Chemical Monthly》2002,133(7):931-943
Summary. Hydrido substituted stannasilanes of the type or (Z = H, Me, Ph; R, R′ = alkyl, Ph) are accessible by reaction of either alkali metal stannides (MSn(Z)R
2; M = Li, Na) with halogen substituted silanes (; X = F, Cl) or chlorostannanes (R
2SnCl2, Ph3SnCl) and fluorosilanes in the presence of magnesium. Stannasilanes with halogen substituents at the silicon as well as the tin atom are formed by
treatment of the hydrido substituted stannasilanes with CHCl3 or CCl4. The hydrido substituted stannasilanes decompose in contact with air to distannanes and siloxanes or to the linear (
t
Bu2Sn(–O–
t
Bu2Si–OH)2) and cyclic ((–
t
Bu2Sn–O–
i
Pr2Si–O–)2) stannasiloxanes.
Received November 29, 2001. Accepted (revised) January 16, 2002 相似文献
16.
Yan Fang Shengli L. Gao Sanping P. Chen Rongzu Z. Hu Qizhen Z. Shi 《Monatshefte für Chemie / Chemical Monthly》2003,134(7):983-989
Summary. The crystal growth process of aqua methioninezinc (II) sulfate (Zn(Met)SO4·H2O) from water and acetone was investigated using a Calvet microcalorimeter. The heat produced and the rate of heat production
during the crystal growth process at 293.15, 295.15, 298.15, and 300.15 K were measured. On the basis of these results the
rate constant, the Eyring parameters (the apparent activation enthalpy, the activation entropy, and the activation free energies), and the Arrhenius parameters (the activation energy, the pre-exponential factor) of the crystal growth process have been obtained. The results
have shown that this crystal growth process accords with the Burton-Cabrera-Frank dislocation theory.
Corresponding author. E-mail: weizhang@nwu.edu.cn
Received August 16, 2002; accepted (revised) December 3, 2002
Published online May 15, 2003 相似文献
17.
Rahman Hosseinzadeh Ali Sharifi Kourosh Tabar-Heydar Farshid Mohsenzadeh 《Monatshefte für Chemie / Chemical Monthly》2002,133(11):1413-1415
Summary. N,N-Dimethylhydrazones of ketones and aldehydes undergo facile cleavage to the corresponding carbonyl compounds upon exposure
to microwaves in water containing a catalytic amount of PdCl2–SnCl2 in high yields.
Corresponding authors. E-mail: rahman@umz.ac.ir
Received December 27, 2001. Accepted (revised) February 6, 2002 相似文献
18.
Stefan E. Boiadjiev David A. Lightner 《Monatshefte für Chemie / Chemical Monthly》2002,133(11):1469-1480
Summary. Malonic ester derivatives of ethyl and methyl 3,5-dimethyl-4-(1′-iodoneopentyl)-1H-pyrrole-2-carboxylate exhibit restricted rotation about the pyrrole C(4)–C(1′) bond due to the bulky 1′-tert-butyl and malonic ester groups and the ortho effect at C(4) of the sterically crowded 3,5-dimethylpyrrole. The malonates belong to a rare class of atropisomers with restricted
rotation about an sp3–sp2 C–C bond, and they undergo diastereomeric separation by TLC and crystallization: the diastereomers are stable in solution
at room temperature. A crystal of one of the diastereomers, suitable for X-ray crystallography, gave the relative configuration
of the chiral axis and stereogenic center at C(1′). Dynamic NMR studies of the purified diastereomers provide kinetic and
thermodynamic parameters associated with the atropisomerism: ΔG
‡ = 132–134 kJ/mol (∼32 kcal/mol) at 383 K in C2D2Cl4 solvent.
Corresponding author. E-mail: lightner@scs.unr.edu
Received July 1, 2002; accepted July 8, 2002 相似文献
19.
Peter Klampfer Primož Benkič Maja Ponikvar Ana Rahten Antonija Lesar Adolf Jesih 《Monatshefte für Chemie / Chemical Monthly》2003,134(1):1-9
Summary. Hydrazinium(+2) fluoroarsenate(III) fluoride was prepared by the reaction of hydrazinium(+2) fluoride and liquid arsenic
trifluoride. N2H6AsF4F is stable at 273 K, but decomposes slowly at room temperature. N2H6AsF4F crystallizes in the orthorhombic space group Pnn2 with a = 774.0(2) pm, b = 1629.2(4) pm and c = 436.6(1) pm; V = 0.5506(3) nm3, Z = 4 and d
c
= 2.461 g cm−3. The structure consists of N2H6
2+ cations, AsF4
− anions, and F− anions and is interconnected by a hydrogen bonding network. Distorted trigonal-bipyramidal AsF4
− units are very weakly interconnected and form chains along the b axis. Bands in the Raman spectrum are assigned to the vibrations of N2H6
+2 cations and AsF4
− anions.
Corresponding author. E-mail: adolf.jesih@ijs.si
Received April 18, 2002; accepted July 15, 2002 相似文献
20.
Summary. Diethyl 3,3′-di-tert-butyl-4,4′-dimethyl-2,2′-bipyrrole-5,5′-dicarboxylate was synthesized in four steps from ethyl 3,5-dimethyl-1H-pyrrole-2-carboxylate. The CH2 hydrogens of the ethyl ester groups of the former are diastereotopic in the 1H-NMR, consistent with axial chirality of the bipyrrole and restricted rotation about the 2,2′-bipyrrole bond, due to the
tert-butyl groups. An X-ray structure of the crystalline target compound shows the pyrrole rings are twisted out of coplanarity
by 84.5°.
Corresponding author. E-mail: lightner@scs.unr.edu
Received September 2, 2002; accepted September 13, 2002
Published online February 20, 2003 相似文献