Synthesis and tautomeric transformations of 2-(tert-butyl)-1,2,4-benzotriazine-3(2H)-thiones

Treatment of 2-(tert-butyl)-1,2,3,4-benzotetrazinium tetrafluoroborates with sodium thiocyanate afforded 2-(tert-butylazo)phenyl isothiocyanates 3, which exist in equilibrium with 2-(tert-butyl)-1,2,4-benzotriazine-3(2H)-thiones 3′. The equilibrium depends on the substituents R in the benzene ring: the percentage of the open isomer 3 is about 20% for R = H or Me; for R = Cl or Br, the equilibrium is completely shifted to cyclic isomer 3′. The equilibrium is slow on the time scale of the ¹H and ¹³C NMR experiments. For compounds 3a/3′a (R = H), the spectra at 24 °C show two sets of signals, while those at 0 °C contain only signals for isomer 3′a. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1192–1195, July, 2006.     

对一个大单轴磁各向异性镍(Ⅱ)配合物中的磁跃迁的直接观察

最近Ruamps和同事发现三角双锥构型的Ni（Ⅱ）配合物[Ni（Me₆tren）Cl]ClO₄（1，Me₆tren=tris（2-（dimethylamino）ethyl）amine）具有大的单轴磁各向异性（J.Am.Chem.Soc.，2013，135：3017-3026）。他们利用HF-EPR研究获得横向零场分裂（ZFS）参数E=1.56（5）cm^-1但未能确定轴向零场分裂参数D。在本工作中，我们利用0~17.5 T和5 K的变磁场远红外光谱（FIRMS）来检测自旋基态S=1中的M_S=±1和M_S=0态之间的磁跃迁。在FIRMS中直接观察到Zeeman分裂态之间的跃迁，得出轴向ZFS参数D=-110.7（3）cm^-1。我们对1的晶体结构进行了Hirshfeld表面分析，揭示了1分子中的阳离子与阴离子之间以及分子之间的相互作用。     

Influence of vanadium doping on the behavior of YBa_2Cu_3O_7-y

YBa2Cu3-xVxO7-y(x=0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6) superconductors have been prepared. X-ray diffraction shows that the system remains orthorhombic for all compositions studied, but for x > 0.4 V2O5 was detected as an impurity phase. Substitution of V5+ for Cu2+ occurs in the Cu(2) sites on the Cu(2)-O planes. The introduction of the high valence element, vanadium, produces the extra free-electrons. These electrons recombine with the positive carrier of the system. It makes depression of the mobility and the Hall number of YBa2Cu3-xVxO7-v and also results in a depression of TC.     

Polynuclear nonfused tetrazole-, 1,3,4-oxadiazole-, and 1,2,3-triazole-containing systems

Polynuclear nonfused blocks containing 1,2,3-triazole, 1,3,4-oxadiazole, and tetrazole rings were synthesized by reaction of C-substituted tetrazoles with carboxylic acid chlorides, as well as by cycloaddition of 2-azidomethyl-1,3,4-oxadiazoles at the triple bond of acetylenic compounds.     

Infrared spectra of cyclic ethers and their derivatives

The IR spectra of six monosubstituted and of four 2,6-disubstituted 1,4-dioxanes have been studied in the 650–1800cm^–1 region. The assignment of the bands due to the vibrations of the 1,4-dioxane ring and to the deformation vibrations of the methylene groups of the ring is given. The appearance of a whole series of new absorption bands on passing from unsubstituted 1,4-dioxane to its derivatives is explained by the change in the symmetry of the molecule and the removal of the prohibition from the vibrations previously inactive in the IR spectra connected with this reduction in symmetry. It is proposed to use, in order to confirm the presence of a 1,4-dioxane ring in a molecule from the results of IR spectroscopy, not only the 1126-cm^–1 band but the whole group of bands lying in the frequency ranges 800–950, 1000–1150, and 1200–1300 cm^–1.For part I, see [3].     

Variation of physicochemical properties in the aggregates of structual isomers

The regions of variation of density, enthalpy of formation, and detonation velocity of all of the formally possible structual isomers were determined for several molecular formulas of C,H,N,O-containing explosives. The histograms of the distribution of the structual isomers over these parameters were constructed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 859–862, May, 1995.The authors are grateful to Mrs. I. D. Solodukhina for the design of the graphical material.The work was carried out with the financial support of the Russian Foundation for Basic Research (Project No. 94-03-09323).     

NMR studies of solid state—solvent and H/D isotope effects on hydrogen bond geometries of 1:1 complexes of collidine with carboxylic acids

¹H and ¹⁵N NMR spectra of 10 complexes exhibiting strong OHN hydrogen bonds formed by ¹⁵N-labeled collidine and different proton donors, partially deuterated in mobile proton sites, have been observed by low-temperature NMR spectroscopy using a low-freezing CDF₃/CDF₂Cl mixture as polar aprotic solvent. The following proton donors have been used: HCl, formic acid, acetic acid, various substituted benzoic acids and HBF₄. The slow hydrogen bond exchange regime could be reached below 140 K, which allowed us to resolve ¹⁵N signal splittings due to H/D isotopic substitution. The valence bond order model is used to link the observed NMR parameters to hydrogen bond geometries. The results are compared to those obtained previously [Magn. Reson. Chem. 39 (2001) S18] for the same complexes in the organic solids. The increase of the dielectric constant from the organic solids to the solution (30 at 130 K) leads to a change of the hydrogen bond geometries along the geometric correlation line towards the zwitterionic structures, where the proton is partially transferred from oxygen to nitrogen. Whereas the changes of spectroscopic and, hence, geometric parameters are small for the systems which are already zwitterionic in the solid state, large changes are observed for molecular complexes which exhibit almost a full proton transfer from oxygen to nitrogen in the polar liquid solvent.     

Simple route to 3-(2-indolyl)-1-propanones via a furan recyclization reaction

A simple route to 1-R-3-(2-indolyl)-1-propanones has been elaborated based on recyclization of 2-(2-aminobenzyl)furan derivatives. Being a modification of the Reissert indole synthesis, our approach employs the furan ring as a source of carbonyl function. This approach is general and allows varying of substituents in aromatic ring as well as in 3-position of indole nucleus.     

Nitro derivatives of 3-hydroxyquinoline

The nitration of 3-hydroxyquinoline with concentrated nitric acid in sulfuric acid at ?30 to +30°C gives 5-nitro-3-hydroxyquinoline (85–92%) and 7-nitro-3-hydroxyquinoline (7–12%). 4-Nitro-3-hydroxyquinoline is formed in 70% yield by nitration in acetic acid. 4,5-Dinitro-3-hydroxyquinoline is formed by further nitration of 4- and 5-nitro-3-hydroxyquinolines.     

Measurements of the spin rotation parameterR in high energy elastic scattering and helicity amplitudes at Serpukhov energies

The spin rotation parameterR in pp and ⁺ p elastic scattering at 45 GeV/c has been measured at the Serpukhov accelerator, for ¦t¦ ranging from 0·2 to 0·5 (GeV/c)². The results are presented, together with previousR measurements at lower energies, and are compared with the predictions of Regge pole models. The equality of the values forR in proton-proton and pion-proton scattering, within the experimental errors, is a test of factorization of the residues.Ans-channel helicity amplitude analysis for pion-nucleon scattering at 40 GeV/c is made using all available data, Significant results are obtained for the isoscalar exchange amplitudes. The helicity flip in isoscalar exchange is non negligible. The energy dependence of this amplitude, at 6, 16 and 40 GeV/c, is compared with predictions of Reggs pole models.Presented by L.van Rossum at the Symposium on Hadron-Hadron Scattering at High Energies, Liblice, Czechoslovakia, June 16–21, 1975.