The first definitive example of oxidative addition of acyclic vinyl selenide to M(0) complex

The principle of C-S bond activation of acyclic vinlyl sulfide by platinum(0)-complex was applied to the C-Se bond fission of vinyl selenide. The substrate possessing Ph and ArSe (Ar = C₆H₄Cl-p) substituents at the β-carbon successfully reacted with Pt(0)-complex at 25 °C to produce the vinyl platinum in good yield and its structure was unambiguously determined by X-ray crystallographic analysis. When (Z)-(Me₃Si)(ArSe)C(H)(SeAr) was employed as a reaction substrate, following β-Se elimination took place to liberate Me₃SiCCH with the production of [trans-Pt(SeAr)₂(PPh₃)₂]. The oxidative addition of C-Se bond of (E)-(Ph)(H)CC(H)(SeAr) to Pt(0) was also confirmed at 25 °C, while no C-S bond-breaking occurred when the corresponding vinyl sulfide was exposed to the same reaction conditions, demonstrating that the cleavage of C-Se bond was more facile than that of C-S bond.     

Construction of an Artificial Ferrimagnetic Lattice by Lithium Ion Insertion into a Neutral Donor/Acceptor Metal–Organic Framework

Construction of a molecular system in which the magnetic lattice exhibits long‐range order is one of the fundamental goals in materials science. In this study, we demonstrate the artificial construction of a ferrimagnetic lattice by doping electrons into acceptor sites of a neutral donor/acceptor metal–organic framework (D/A‐MOF). This doping was achieved by the insertion of Li‐ions into the D/A‐MOF, which was used as the cathode of a Li‐ion battery cell. The neutral D/A‐MOF is a layered system composed of a carboxylate‐bridged paddlewheel‐type diruthenium(II,II) complex as the donor and a TCNQ derivative as the acceptor. The ground state of the neutral form was a magnetically disordered paramagnetic state. Upon discharge of the cell, spontaneous magnetization was induced; the transition temperature was variable. The stability of the magnetically ordered lattice depended on the equilibrium electric potential of the D/A‐MOF cathode, which reflected the electron‐filling level.     

Simultaneous observation of oxygen uptake curves and electronic states during room-temperature oxidation on Si(0 0 1) surfaces by real-time ultraviolet photoelectron spectroscopy

Ultraviolet photoelectron spectroscopy was used to measure the oxygen uptake, changes in work function due to the surface dipole layer of adsorbed-oxygen atoms, Δ?_SDL, and changes in band bending due to the defect-related midgap state, ΔBB, simultaneously during oxidation on Si(0 0 1) surface at room-temperature, RT, under an O₂ pressure of 1.3 × 10⁻⁵ Pa. The oxygen dosage dependence of Δ?_SDL revealed that dissociatively adsorbed-oxygen atoms occupy preferentially dimer backbond sites at the initial stage of Langmuir-type adsorption, which is associated with a rapid increase of ΔBB. When raising temperature to ∼600 °C, such preferential occupation of the dimer backbond sites by oxygen atoms is less significant and ΔBB becomes smaller in magnitude. The observed relation between Δ?_SDL and ΔBB indicates that point defects (emitted Si atoms + vacancies) are more frequently generated by oxygen atoms diffusing to the dimer backbond sites at lower temperature in RT −600 °C.     

Linewidth and relative intensity noise measurements of longitudinal modes in ultrahigh-speed mode-locked laser diodes

The longitudinal linewidth and corresponding relative intensity noise (RIN) of 10- and 40-GHz mode-locked laser diodes are measured for the first time to our knowledge. It is shown that the cavity Q value is a dominant parameter of the linewidth. It is also shown that the linewidth of the individual modes is almost constant. This means that the phase noise of each mode is almost the same in the mode-locked condition. The RIN value is larger for modes that are distant from the center longitudinal mode. This mode dependence is a consequence of the mode partition noise.     

Finite temperature neutral-ionic transition and lattice dimerization in charge-transfer complexes: QMC study

We numerically investigate the neutral-ionic (NI) phase transition on the basis of the ionic extended Hubbard model with electron-lattice coupling as well as inter-chain Coulomb interaction. Finite-temperature (T) phase transitions are examined by a quantum Monte Carlo method, within adiabatic approximation for the lattice displacement together with inter-chain mean-field treatment. The NI transition either with or without the electron-lattice coupling is of first-order at low-T and transforms into a cross-over regime with increasing T. We confirm there exist two phases in the ionic region: with and without lattice dimerization, as suggested in recent experiments. The former is ferroelectric, which is rooted in the Coulomb interactions and a spin-Peierls mechanism.     

The PMe3-catalyzed addition of enantiomerically pure (−)-MenthylO(Ph)P(O)H to electron-deficient alkenes: an efficient way for the preparation of P-stereogenic compounds

A variety of P-stereogenic organophosphorus compounds can be readily prepared by stereoretentive addition. The PMe₃-catalyzed addition of optically active (?)MenthylO(Ph)P(O)H compounds to electron deficient alkenes occur stereospecifically, to produce the corresponding P-stereogenic adducts in high yields. By simply removing the volatiles under vacuum, spectroscopically pure products can be obtained. The present method provides a salt-free clean process for the preparation of P-chiral organophosphorus compounds.     

Facile iodination of the vinyl groups in protoporphyrin IX dimethyl ester and subsequent transformation of the iodinated moieties

Iodination of protoporphyrin IX dimethyl ester using phenyliodine bis(trifluoroacetate) (PIFA) and I₂ was studied. Iodine added to both the C3- and C8-vinyl groups equally to afford the iodohydrin or iodoether in the presence of water or alcohol, respectively. Any meso-hydrogen atom was not substituted by an iodine atom under these conditions, although both the vinyl group and one of the meso positions of methyl pyropheophorbide-a bearing a chlorin π-system, a chlorophyll-a derivative, was modified with PIFA and I₂. The reaction intermediates derived from the porphyrin were more reactive than those from the chlorin and liable to form intermolecular linkages. The obtained 2-iodo-1-hydroxyethyl group was transformed into a formyl group by a mild treatment. The corresponding iodoether moiety was readily converted into the acetyl group under basic conditions. These transformations were also applicable to smaller olefins such as styrene.     

Determination of composition distribution of acrylonitrile-styrene copolymers by thin-layer chromatography

Determination of chemical composition distribution of acrylonitrile-styrene copolymers was carried out by thin-layer chromatography (TLC). A mixture of benzene and methyl ethyl ketone gave the most suitable calibration curve of R_f values versus acrylonitrile (AN) contents, where a concentration gradient technique was applied for development. Average AN contents obtained by TLC are coincident with those found by elemental analysis. The copolymers extracted from ABS resins are sufficiently arranged in the order of breadth of composition distribution by using the data from TLC. The agreement between the composition distribution curve and that from the theory of copolymerization is good.