Reactions of urotropine (C6H12N4) with trimethylmetal derivatives of Al, Ga, In und Tl in various () molar ratios lead to stable and monomeric , or adducts in good yields, but no addition product could be isolated. The vibrational spectra (IR and Raman) of all compounds are recorded and partly assigned. Some characteristic frequencies of the C6N4-skeletons clearly show the symmetry changes in the series of the → → adducts (C3ν → C2ν → C3ν). The X-ray structure determinations of C6H12N4·.GaMe3 (MeCH3) and C6H12N4·.2GaMe3, are in good agreement with the vibrational spectra. Both compounds crystallize in monoclinic space groups (P21 and C2/c). The GaN distances are around 214 pm, and the values for the C6N4-skeletons are not significantly different from those for free urotropine. 相似文献
Three different types of butanolide complexes with EtnAlCl3?n in the molar ratios and have been investigated by IR with 1M NMR spectroscopy. The butanolides form and complexes with ethylaluminium halides, but with triethylaluminium only complexes are formed. The complexes are intermediates in the cleavage of butanolides. 相似文献
The structure of wüstite Fe1?zO is studied by neutron diffraction on one polycrystalline sample under equilibrium conditions at high temperature. The mean isotrope temperature factor B is expressed as a sum of two parts, BTh and BSt, which vary linearly with a single parameter, respectively temperature and z. A classification is established for clusters () settled from m vacancies in octahedral sites and n FeIII ions in interstitial sites. Sixteen values have been experimentally determined for the vacancies to interstitials ratio . A constant value of ?, which is lower than 3, is observed. This result characterizes the short-range order. It eliminates several possibilities of clusters like those obeying the relation . Other clusters, namely () or (), might agree. The () and () clusters obtained from () clusters joined by an edge would be the more likely. An analysis of diffuse scattering eliminates the hypothesis of large domains with inverse spinel structure. The structural differences between the three varieties W1, W2 and W3 would not be found in a structural change of clusters. 相似文献
Microwave—optical double resonance signals have been detected in a mass-selected ion-beam spectrometer for 12C16O+. With the optical excitation of fluorescence from the R1 () line of the (0,0) band of the A2Π ← X2∑ transition of 20350.6 cm?1, the microwave resonances occurred at 118101.8 ± 0.2 MHz and at 117694 ± 2 MHz corresponding to the N= 1, J = ← N = 0, J = and the N = 1, J = ← N = 0, J = transitions. 相似文献
The structural parameters of α- and β-CdUO4 crystals are determined by X-ray powder diffraction technique. α-CdUO4 is rhombohedral and cell parameters are a = 6.233(3) Å and α = 36.12(5)°. β-CdUO4 crystallizes in a C-centered orthorhombic cell with a = 7.023(4), b = 6.849(3), c = 3.514 (2) Å. The space groups are for α-CdUO4 and Cmmm for β-CdUO4. α-CdUO4: 1U in (000), 1Cd in (), 2O(1) in ±(uuu), 2O(2) in ±(vvv); u = 0.113, v = 0.350, Z = 1. β-CdUO4: 2U in (), 2Cd in (), 4O(1) in (), 4O(2) in (); x = 0.159, y = 0.278, Z = 2. β-CdUO4 contains collinear uranyl UO2+2 groups with a UO(1) distance of 1.91 Å, located either along or parallel to the c axis whereas the UO(1) bond length in α-CdUO4 is 1.98 Å which is longer than the usual uranyl bond length. 相似文献
The irreversible polarographic reduction of methyl bromide was studied in aqueous solution in the presence of various base electrolytes.E values became more positive with increasing charge density and surface activity of the cations. Mixed electrolytes with alkali metal salts and tetraalkylammonium salts or cationic surfactants suppressed this increase inE values. With such mixed electrolytes containing highly active surfactants of sufficient charge density, a normal polarographic determination of methyl bromide is possible. The final diffusion rate of the active component has also a considerable effect on E values so that the E values of such systems cannot be characterized by the solution composition alone. 相似文献
tert-Butyl azidoformate () reacts with the conjugate bases of , , (R1 = R2 = CH3), and (R1 = CH3, R2 = H) to give products [, , , and , respectively] in addition to the expected N-(tert-butoxycarbonyl)indole derivatives. 相似文献
Irradiation of thioxanthenethione with the alkyl- and alkoxysubstituted butatrienes a-d gives the thietanes a-d the cyclobutanethione is formed as a byproduct. Free radical addition of iC3H7SH to a predominantly occurs via terminal attack of the thiyl radical on the π-system. 相似文献
In measuring inter-phase distribution coefficients (k)it is often convenient, and sometimes necessary, to obtain all of the analytical data from one phase. A rigorous formula, applicable to both low and high k values has been derived; measurements of the distribution of mercury, methylmercury and 67Cu2+ between various pairs of phases with this formula gave k values similar to those obtained from other approaches. 相似文献
The surprising formation of C22H32N2S2 from the title compound 1 at 45°C involves the interaction of the basic adamantanethione S-methylide () with its acidic precursor , in the course of which the anion undergoes electrocyclic ring opening; the acid and base functions offer the clue to a prolific chemistry of the thiadiazoline and the thiocarbonyl ylide . 相似文献
The rotating disk (RDE) and the rotating ring-disk (RRDE) electrode techniques have been employed to study the cathodic behavior of eight bisarenechromium complexes and seven corresponding arenes in DMSO solutions. In the first electrochemical step of the process reversible addition of one electron results in anion-radicals, whose formation has been demonstrated for certain arenes and chromium π-complexes by oxidation of these particles on the ring electrode.Substituents on different ligands of bisarenechromium complexes were found to exert pronounced mutual influences. The role of the chromium atom in transfer of electronic effects from one ligand to another is discussed.It was found that a linear correlation exists between the variations in the free energy of the equilibrium “initial compound anion-radical” (due to coordination of free arene with chromium which is displayed as a shift of the cathodic process half-wave potential ΔECL) and the half-wave potential of the oxidation of the corresponding Cr0 π-complex to a cation EX ΔECL = a + αEX At EX < ?0.3 V, complex formation slows down the cathodic process and at EX > ?0.3 V the process is facilitated. 相似文献
The new compound Tl6[Ge2Te6] was prepared by thermal synthesis from the elements. The material is triclinic, space group , with a = 9.471(2), b = 9.714(2), c = 10.389(2) Å, α = 89.39(1), β = 97.27(1), γ = 100.79(1)°, and Z = 2. The crystal structure was determined from single-crystal intensity data measured by means of an automated four-circle diffractometer and refined to an R value of 0.053 for 1831 observed reflections. Tl6[Ge2Te6] is characterized by Ge2Te6 units with GeGe bonds which are linked into a three-dimensional structure by Tl atoms coordinated to essentially six Te atoms. The most important mean distances are Å, Å, and Å. The lone 6s electron pairs of the thallium(I) atoms exhibit significant stereochemical activity. Tl6[Ge2Te6] represents a new structure type. 相似文献
Relativistic and non-relativistic Hartree—Fock calculations including np and np orbitals in the valence MO are reported for the molecules BH, AlH, GaH, InH and TlH. The relativistic contraction of the bond length reaches 7.0% for TlH. Relativistic effects make the chemical bond stronger for AlH, GaH and InH and weaker for TlH. The calculated force constants and dissociation energies are in reasonable agreement with experiment. A change from npσ towards np bonding takes place along the series. For Tl the MO is only 39% p as compared with the non-relativistic value of 67%. This probably explains the dominant monovalency of thallium. 相似文献
Crystal structures for the fluorite-related phases CaHf4O9) and Ca6Hf19O44 () have been determined from X-ray powder diffraction data. qf1 is monoclinic, , with a = 17.698 Å, b = 14.500Å, c = 12.021 Å, β = 119.47° and Z = 16. qf2 is rhombohedral, , with a = 12.058 Å, α = 98.31° and Z = 2.Both phases are superstructures derived from the defect fluorite structure by ordering of the cations and of the anion vacancies. The ordering is such that the calcium ions are always 8-coordinated by oxygen ions, while the hafnium ions may be 6-, 7-, or 8-coordinated. The closest approach of anion vacancies is a fluorite subcell vector, and in each structure vacancies with this separation form strings. 相似文献
Stable analogues of PGI2, 7-hydroxy- and 7-acetoxy-PGI2, were synthesized from protected PGI2 methyl ester via sulfoxides , through stereocontrolled sulfoxide-sulfenate rearrangement. 相似文献
Samples of poly(12-dodecanelactam) (polylaurolactam, nylon 12) with n 1 × 103?33 × 103 were prepared. Polymerizations initiated with water or with lauric acid proceeded under conditions for minimum changes in end-group concentration. Values of n were calculated from the end-group content and n from light scattering in the mixture m-cresol/60 vol% of 2.2,3,3-tetrafluoropropanol. From measurements of intrinsic viscosity in m-cresol, the relationship [n] ? n was established in the given range of n. The relationship [n] ? w for w from 3.3 × 103 to 125 × 103 has been established. 相似文献