Dirhenium Carbonyl Complexes Bearing 2-Vinylpyridine, Morpholine and 1-Methylimidazole Ligands

Treatment of the labile compound [Re2(CO)8(MeCN)2] with 2-vinylpyridine in refluxing benzene affords exclusively the new compound [Re2(CO)8(μ-η1:η2-NC5H4CHCH2)] (1) in 39% yield in which the μ-η1:η2-vinylpyridine ligand is coordinated to one Re atom through the nitrogen and to the other Re atom via the olefinic double bond. Reaction of [Re2(CO)8(MeCN)2] with morpholine in refluxing benzene furnishes two compounds, [Re2(CO)9(η1-NC4H9O)] (2) and [Re2(CO)8(η1-NC4H9O)2] (3) in 5% and 29% yields, respectively. Reaction of [Re2(CO)8(MeCN)2] with 1-methylimidazole gives [Re2(CO)8{η1-NC3H3N(CH3)}2] (4) and the mononuclear compound fac-[ReCl(CO)3{η1-NC3H3N(CH3)}2] (5) in 18% and 26% yields, respectively. In the disubstituted compounds 2 and 4, the heterocyclic ligands occupy equatorial coordination sites. The mononuclear compound 5 consists of three CO groups, two N coordinated η1-1-methylimidazole ligands and a terminal Cl ligand. The XRD structures of complexes 1, 3 and 5 are reported

Phonon, Two-Magnon and Electronic Raman Scattering of Fe1+yTe1-xSex

We have measured Raman scattering spectra of single-crystalline FeTe0.6Se0.4 (T_c ~ 14.5 K) and its parent compound Fe1.074Te at various temperatures. In the parent compound Fe1.074Te, A1g and B1g modes have been observed at 157.5 and 202.3 cm-1, respectively, at 5 K. These frequencies qualitatively agree with the calculated results. Two-magnon excitation has been observed around 2300 cm-1 for both compounds. Temperature dependence between the electronic Raman spectra below and above T_c has been observed and 2\Delta and 2\Delta/k_BT_C have been estimated as 5.0 meV and 4.0, respectively.Comment: 8 pages, 8 figures, to be published in Phys. Rev.

{Spin polarization tuning in Mnx_{x}Fe1−x_{1-x}Ge3_{3}

Experimentally, the intermetallic compound Mn$_{4}$FeGe$_{3}$ has been recently shown to exhibit enhanced magnetic properties and spin polarization compared to the Mn$_{5}$Ge$_{3}$ parent compound. The present {\em ab-initio} study focusses on the effect of Fe substitution on the electronic and magnetic properties of the compound. Our calculations reveal that the changes on the Fermi surface of the doped compound are remarkable and provide explanations for the enhanced spin-polarization observed. Finally, we show that it is indeed possible to tune the degree of spin-polarization upon Fe doping, thus making the Mn$_{1-x}$Fe$_{x}$Ge$_{3}$ intermetallic alloy very promising for future spintronic applications.Comment: 8 pages, 1 fi

COMPOUNDING OF BASEMAH LANGUAGE: An Effort to Understand the Uniqueness of Local Languages

The objectives of this research are to describe the compound and identify its kinds in Basemah language. Compound is words formed by combining roots, and the much smaller category of phrasal words, that is items that have internal structure of phrases but function syntactically as words. Compounds cannot be connected by conjunction (McCharty, 2002). This research employed a qualitative research design, as suggested by Sugiyono that qualitative is an artistic method because the process of the research is about art and it is called interpretive method because the result of data research is about interpretation of data which are found in the field (2013:7-8). Therefore, this study uses a descriptive method in describing the finding of the data. The method of this research is descriptive qualitative method. The result of this research shows that compounding in Basemah language is distinguished based on its structures: noun-adjective, noun-noun, noun-verb and compound with certain words that relate to Endocentric compound, exocentric compound and copulative compound

Fermiology and transport properties of the half-metallic itinerant ferromagnet CoS2_2: influence of spin orbit coupling

Electronic structure calculations were performed on the compound CoS$_2$, an itinerant ferromagnet whose magnetic properties can be understood in terms of spin fluctuation theory. We have identified nesting features in the Fermi surface of the compound, active for long wavelength spin fluctuations. The electronic structure of the material is close to a half-metal. We show the importance of introducing spin-orbit coupling (SOC) in the calculations, that partially destroys the half-metallicity of the material. By means of transport properties calculations, we have quantified the influence of SOC in the conductivity at room temperature, with an important decrease comparing to the GGA alone conductivity. SOC also helps to understand the negative 0 of the material, whose conductivity varies by a few percent with the introduction of small perturbations in the states around the Fermi level.Comment: 8 pages, 8 figure

Magnetic Excitations in quasi two-dimensional Spin-Peierls Systems

A study is presented of a two-dimensional frustrated and dimerized quantum spin-system which models the effect of inter-chain coupling in a spin-Peierls compound. Employing a bond-boson method to account for quantum disorder in the ground state the elementary excitations are evaluated in terms of gapful triplet modes. Results for the ground state energy and the spin gap are discussed. The triplet dispersion is found to be in excellent agreement with inelastic neutron scattering data in the dimerized phase of the spin-Peierls compound CuGeO_3. Moreover, consistent with these neutron scattering experiments, the low-temperature dynamic structure factor exhibits a high-energy continuum split off from the elementary triplet mode.Comment: 8 pages, Revtex, 8 eps-figure

Quantum Phase Transition from a Spin-liquid State to a Spin-glass State in the Quasi-1D Spin-1 System Sr1-xCaxNi2V2O8

We report a quantum phase transition from a spin-liquid state to a spin-glass state in the quasi-one dimensional (1D) spin-1 system Sr1-xCaxNi2V2O8, induced by a small amount of Ca-substitution at Sr site. The ground state of the parent compound (x = 0) is found to be a spin-liquid type with a finite energy gap of 26.6 K between singlet ground state and triplet excited state. Both dc-magnetization and ac-susceptibility studies on the highest Ca-substituted compound (x = 0.05) indicate a spin-glass type magnetic ground state. With increasing Ca-concentration, the spin-glass ordering temperature increases from 4.5 K (for the x = 0.015 compound) to 6.25 K (for the x = 0.05 compound). The observed results are discussed in the light of the earlier experimental reports and the theoretical predictions for a quasi-1D spin-1 system.Comment: 26 pages, 8 figures, 3 table

Sodium pentafluorophenylborate

The crystal structure of the title compound, Na[(C6F5)BH3], is composed of discrete anions and cations. The sodium cations are surrounded by four anions with three short Na...B [2.848 (8), 2.842 (7) and 2.868 (8) Å] and two short Na...F contacts [2.348 (5) and 2.392 (5) Å], forming a three-dimensional network. The anion is the first structural example of a pentafluorophenyl ring carrying a BH3 group