The infrared spectra, transmittance, and polarized reflectance of Cs3CoCl5 are reported. The group theoretical analysis was executed and a vibrational assignment proposed on the basis of D4h symmetry. Factor group and site effects are discussed. 相似文献
Complete assignments of chemical shifts and extensive assignments of carbon-proton coupling constants are presented for the 3-, 4-, 6-, 7- and 8-methylcoumarins, together with similar parameters for 5,8- and 6,8-dimethylcoumarin. Shifts in 6,8-dimethylcoumarin can be predicted with high precision from the substituent effects observed in the 6- and 8-methyl derivatives, and shifts are predicted for the 5-methyl derivative, which was not studied. 相似文献
The proton chemical shift tensor of the hydroxyl proton in calcium hydroxide has been measured using multiple pulse NMR techniques. The tensor is axially symmetric with susceptibility corrected components σtT = ?9.3 ± 1 ppm and ppm relative to TMS. 792 79 相似文献
The stabilities of the hydrated uranyl phosphates (UO2)3(PO4)2 · 4 H2O, UO2HPO4 · 4 H2O, and UO2(H2PO4) · 3 H2O have been reinvestigated. The compounds identified by thermal analysis have been prepared isothermally and characterized by their strongest X-ray reflections. During dehydration, oxygen was not evolved and the crystalline compounds (UO2)3(PO4)2, (UO2)2P2O7, UO2(PO3)2, and probably (UO2)3P4O)13 were found.
At still higher temperatures, the uranyl phosphates are reduced. The decomposition products lose phosphorus oxide above 1300–1400°C. The present results are summarized in a tentative pseudo-binary phase diagram UOx(x = 3 to 2)—UO2(PO3)2. 相似文献
2,3-Dicarbomethoxy-7,7-dimethyl-7-silabicyclo[2.2.1]hepta-2,5-diene (III) on photolysis gave dimethyl tetraphenylphthalate whereas the photolysis of 7,7-dimethyl-7-silabicyclo[2.2.1]hep-5-ene-2,3-dicarboxylic anhydride (XIa) resulted in the formation of 1,1-dimethyl-2,3,4,5-tetraphenyl-1-silacyclopentadiene (XIIIa). The thermolysis of XIa also gave rise to XIIIa. Similarly, the photolysis as well as thermolysis of 1,4,5,6,7,7-hexaphenyl-7-silabicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride (XIb) led to hexaphenylsilacyclopentadiene (XIIIb). Attempts to detect radical intermediates in these thermal and photochemical transformations by carrying out the reaction in the presence of hydroquinone, hydrazobenzene, 3,6-diphenyl-1,2-dihydro-1,2,4,5-tetrazine, cumene and tolan were unsuccessful. An attempted preparation of 7-silabicyclo[2.2.1]hepta2,5-dienes by the reaction of silacyclopentadienes such as 1-methyl-1-vinyl2,3,4,5-tetraphenyl-1-silacyclopentadiene (XV) and 1-methyl-1,2,3,4,5-pentaphenyl-1-silacyclopentadiene (XVI) with dimethyl acetylenedicarboxylate resulted in the isolation of dimethyl tetraphenylphthalate indicating that the corresponding 7-silabicyclo[2.2.1]hepta-2,5-dienes are thermally unstable. 相似文献
The conditional solubility of scheelite CaWO4 in molten NaCl?KCl (1:1) has been studied either in oxobasic or oxoacidic media. In the former case it is increased by formation of sparingly soluble CaO according to:Ca2+ + O2CaO(s), pKsCaO = 10800/T ? 5.8 (molality scale) In the later case, WO42- behaves as an oxobase according to the following equilibria:WO42?WO3 (s) + O2? pK0 = 10.0 at 1000 K3 WO42?W3O102? pK3 = 12.7 at 1000KThe latter equilibrium favours an increase in the WVI solubility when pO2- is increased, for instance by injection of HCl. The whole set of results has been summarized by a conditional solubility diagram of scheelite versus pO2-. 相似文献
Energy transfer studies have been made in a terbium-erbium coactivated calibo-glass system at room temperature and at liquid-air temperature. A study of the emission and decay of 5D4 level of Tb3+ has been made by varying the acceptor (Er3+) concentration. Probabilities and efficiencies of energy transfer as well as donor-acceptor distances have been calculated. At low acceptor concentration the decay of the donor (Tb3+) emission has been found to be diffusion limited. At high acceptor concentration the mechanism governing the transfer is found to be dipole-dipole. 相似文献
Pentacarbonyl(diethylaminocarbyne)chromium tetrafluoroborate, [(CO)5− CrCNEt2]BF4 (I), reacts with PPh3 with substitution of CO and formation of trans-tetracarbonyl(diethylaminocarbyne)triphenylphosphanechromium tetra-fluoroborate, trans-[PPh3(CO)4CrCNEt2]BF4 (III). Substitution of CO by PPh3 in neutral trans-tetracarbonyl(halo)(diethylaminocarbyne)chromium complexes, trans-X(CO)4CrCNEt2 (IVa: X = Br, IVb: X = I), leads in a reversible reaction to the corresponding tricarbonyl complexes, mer-X(PPh3)(CO)3− CrNEt2 (V), PPh3 occupying the cis-position to the carbyne ligand. With PPh3 in large excess both reactions follow a first-order rate law. This as well as the activation parameters (ΔH≠ = 104–113 kJ mol−1, ΔS≠ = 64–71 J mol−1 K−1) indicate a dissociative mechanism. 相似文献
The infrared spectra in the OH-stretching and HOH-bending regions of H2O, and in the OH-stretching region of HDO dissolved in a number of ketones and ethers have been recorded. The number of component bands and their wavenumbers, halfwidths and intensities, as well as the total OH-stretching intensity in each solvent, have been interpreted in terms of a model for the types of hydrogen bonded solvent:water complexes formed in these systems.The effect of temperature on the spectra of H2O in some of the ketones has been rationalized on the basis of the equilibrium existing between the different hydrogen bonded species present in solution. 相似文献