The reaction of five-membered cyclic trithiocarbonates with n-butyllithium

It was found that the reaction of five-membered cyclic trithiocarbonates with n-butyllithium in tetrahydrofuran is applicable to the preparation of unsymnetrical linear trithiocarbonates and further to the interconversion of cis- and trans-olefins.     

Preparation and Characterization of Branched β-Cyclodextrins Having Manno-Oligosaccharide Side Chains Derived from Yeast Mannan and Study of Their Functions

Branched -cyclodextrins (-CDs) having manno-oligosaccharide side chains were investigated. Three kinds of monobranched -CDs and five kinds of dibranched -CDs were chemically synthesized using the trichloroacetimidate method. Their structures were analyzed by HPLC, MS, and NMR spectroscopies. The specific interaction between those compounds and mannose-binding lectins (Concanavalin A and Pisum sativum agglutinin) was investigated by inhibition tests of hemagglutinating activity and by using an optical biosensor of the IAsys apparatus with a resonant mirror detector. The results showed that all branched -CDs interactedwith lectins. The binding affinity was 6¹,6⁴-(Man₃)₂- 6¹,6⁴-(Man₂)₂- > 6¹,6⁴-(Man₄)₂--CD when the derivatives were compared on the basis of side chain length and 6¹,6³- 6¹,6⁴- > 6¹,6²-(Man₂)₂--CD when compared on the basis of side chain position.     

Microwave spectrum and conformation of vinyl mercaptan: The syn rotamer

Rotational spectra of vinyl mercaptan (ethenethiol) CH₂CHSH and its isotopic modification CH₂CHSD have been studied by microwave spectroscpy. The molecule has been found to exist in two rotameric forms, syn and anti, associated with different orientations of the SH bond with respect to the vinyl framework. In this paper results are reported for the more stable syn form which is shown to be planar with ground state rotational constants A = 49 815.28(6) MHz, B = 5835.716(14) MHz, C = 5222.081(11) MHz, D_J = 2.85(17) kHz, D_JK = ?33.22(2.08) kHz, and δ_J = 0.425(65) kHz. Spectra have also been observed for the first and second excited states of the SH torsional vibration and the first excited state of the CCS angle bending mode. The dipole moment of the syn rotamer is μ_a = 0.813(1), μ_b = 0.376(4), and μ_total = 0.896(3) D.     

A cems study of119Sn ion-implanted into Ni

Conversion electron Mössbauer spectroscopy (CEMS) was applied to study the behaviour of¹¹⁹Sn atoms implanted into Ni at the accelerating energy of 100–400KeV and doses of 5×10¹⁵–5×10¹⁶ ions/cm² at room temperature. All CEMS spectra were measured at room temperature and successfully analyzed by two components. The energy and dose dependence of CEMS spectra were well explained by the depth distribution of¹¹⁹Sn atoms.     

Millimeter- and submillimeter-wave spectra of AuCl and AuBr in the XΣ electronic ground states

The millimeter- and submillimeter-wave spectra of AuCl and AuBr in the X¹Σ⁺ states were observed by employing a source-modulated microwave spectrometer. The AuCl and AuBr molecules were, respectively, generated in a free space cell by a d.c. glow discharge in Cl₂ and Br₂ with Ar. The gold atoms were supplied by the sputtering reaction from a gold sheet placed on the inner surface of a stainless-steel cathode. Rotational transitions of , , , and in highly excited vibrational states as well as in the ground vibrational states were measured in the region between 189 and 314 GHz. The transition frequencies were analyzed by a least-squares method using a combined-isotopomer Dunham-type term energy expression. The potential constants of gold halides obtained were compared with those of copper and silver halides.     

Microwave response to a magnetic phase transition in a molecular magnet based on [Mn12O12( Me CO2)16(H2O)4] clusters and tetramethyltetrathiafulvalene molecules

The electron paramagnetic resonance spectra of a molecular magnet synthesized from [Mn₁₂O₁₂(MeCO₂)₁₆(H₂O)₄] high-spin clusters and tetramethyltetrathiafulvalene donor organic molecules are investigated. It is revealed that, in the temperature range 5–7 K, there appears an additional signal against the background of the ferromagnetic resonance spectrum. The additional signal consists of a large number of lines and has a resonance nature, because it is observed in the well-reproduced narrow ranges of the constant magnetic field of the spectrometer (300–650 and 850–1300 Oe) at a frequency of 9.4152 GHz. The appearance of the additional signal at a temperature of 5 K is attended by a multiple increase in the magnetic susceptibility of the sample. There is a correlation between the spectral characteristics of the additional signal (such as the average amplitude, the spectral power, etc.) and the parameters of the ferromagnetic resonance spectrum (the resonance field, the linewidth, and the integrated intensity). The assumption is made that the additional signal is associated with the magnetic-field-induced transitions between spin states of Mn₁₂ high-spin clusters for different orientations of crystallites with respect to the external magnetic field. Original Russian Text ? R.B. Morgunov, V.L. Berdinskiĭ, A.I. Dmitriev, Y. Tanimoto, 2007, published in Fizika Tverdogo Tela, 2007, Vol. 49, No. 5, pp. 945–950.     

Diode laser spectrum of HCCl near 5 μm: The ν2 fundamental and accompanying hot bands

The CC stretching band ν₂ of iodoacetylene has been studied by tunable laser spectroscopy in the range of 2037–2071 cm^?1. The hot bands associated with the low-lying bending vibrations ν₄ and ν₅ were observed. For the Π-Π hot bands, the splitting caused l-type doubling was resolved for high J transitions. For the fundamental band the hyperfine splittings due to the ¹²⁷I nuclear quadrupole moment were clearly observed for R(0) and P(1) transitions. Combination of these diode laser spectra with the microwave data allows precise determination of the constants in the ground and excited vibrational states.     

Spin-frustrated antiferromagnets based on <Emphasis Type="Italic">BEDT-TTF</Emphasis> and manganese dicyanamide complexes

The magnetic properties of new radical cation salts (BEDT-TTF)₂[CuMn(dca)₄] (I) and (BEDT-TTF)₂[Mn(dca)₃] (II) [where BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene and dca = N(CN₂)] are investigated using superconducting quantum interference device (SQUID) magnetometry and electron paramagnetic resonance (EPR) spectroscopy. It is established that, at temperatures below 25 K, both salts are characterized by antiferromagnetic deviations from the paramagnetic behavior. The Weiss constants for compounds I and II are determined to be ?5 and ?10 K, respectively. The corresponding correlations in the structure of compound I are short-range correlations and do not lead to a change in the effective spin equal to 5/2. It is found that the widths of the EPR lines attributed to the BEDT-TTF conducting sublattice correlate with the widths of the EPR lines associated with the magnetic sublattice of the Mn(dca) ₃ ^? counterion in the structure of salt II. This correlation suggests that the antiferromagnetic ordering in the magnetic sublattice of compound II affects the spin-lattice relaxation in the BEDT-TTF sublattice. The dependence of the magnetic moment on the magnetic field for compound II at a temperature of 2 K is typical of weakly frustrated uniaxial antiferromagnets and exhibits a kink in a magnetic field of 20 kOe, which corresponds to spin-flop transitions.