Katsuo Murata

Homogeneous liquid-liquid extraction method

A new homogeneous liquid-liquid extraction method was applied to the extraction of molybdenum (VI). This method is based on the high solubility of propylene carbonate in water at higher temperature and is characteristic in taking once the state of a uniform solution consisted of water and the organic solvent during the procedure. Equal volume of warmed propylene carbonate was added to 10ml of 1mM molybdate solution of pH 2.5 adjusted with hydrochloric acid in a stoppered centrifuge tube on a water bath warmed above 70°C. After making a uniform solution by shaking the mixture gently twice or thrice, the solution was cooled and centrifuged to separate two layers. As much as 97% of molybdenum (VI) was extracted into propylene carbonate by a single process. This method is useful especially for the extraction of compounds with slower formation rate, for instance, the metal β-diketonates.

Synthesis and crystal structures of cobalt(III) complexes containing pyridine-2-selenolato and its oxidation products

Abstract A series of mixed cobalt(III) complexes [Co(pySe)3−n(NN)n]n+ [pySe=pyridine-2-selenolato (1−); NN=1,2-ethanediamine (en) and 2,2′-bipyridine (bpy); n=0, 1 and 2] was prepared. The geometrical preference and trans influence of pySe are fairly different from those of pyridine-2-thiolate. These selenolato complexes were oxidized by peracetic acid to give the corresponding pyridine-2-seleninato (pySeO2) and pyridine-2-selenonato (pySeO3) complexes. The crystal structures of the pySeO2 and pySeO3 complexes revealed that the coordination mode change from an original N,Se-four-membered to the N,O-five-membered chelate ring occurred during oxidation and intramolecular hydrogen bonds between the non-coordinated oxygen of pySeO2 or pySeO3 and the amine protons of en stabilize the N,O-coordination mode.

Thermodynamic investigation of glass transition in binary polyalcohols

The glass transition phenomena of binary systems consist of polyalcohols such as ethylene glycol, propylene glycol, 1,3-propanediol and glycerol were investigated by differential scanning calorimetry (DSC). For every system, composition dependence of the glass transition temperature, Tg(x), was reproducible with an empirical form, Tg(x)=[xTg,1+Cg(1−x)Tg,2]/[x+Cg(1−x)]. The composition dependence of Tg predicted based on the entropy theory for regular solutions agreed well with the experimental results in all systems. Excess configurational entropy, ScE, as deviation from the regular solution model, were very small compared to the expected entropy. The behavior of the present system as a regular solution is discussed from the viewpoint of structural change on mixing.

Reactivity of [Cp*RhPtCl6] (Cp* = η5-C5Me5). Synthesis and structures of [(Cp*Rh)2(μ-Cl)3][PtCl5(CH3CONH2)] and [(Cp*Rh)2(μ-Cl)3]2[PtCl6]

Abstract Pentamethylcyclopentadienylrhodium dication, [Cp*Rh(AN)3]2+ (AN = acetonitrile), reacts with hydrogen hexachloroplatinate(IV), H2PtCl6, in acetonitrile to give quantitatively, [Cp*RhPtCl6] (1). The reaction of 1 with [Cp*Rh(AN)3]2+ in acetonitrile provides [(Cp*Rh)2(μ-Cl)3][PtCl5(CH3CONH2)] (2). Recrystallization of 1 from hot water gives a different salt, [(Cp*Rh)2(μ-Cl)3]2[PtCl6] (3). Single-crystal X-ray diffraction analyses have revealed that 2 and 3 are salts of the tri-μ-chloro dirhodium cation and pentachloroplatinate with acetamide or hexachloroplatinate. The acetamide molecule in 2 takes an iminol configuration and coordinates to the platinum atom through the nitrogen atom. Crystal data: [(Cp*Rh)2(μ-Cl)3][PtCl5(CH3CONH2)]·2CHCl3, monoclinic, space group P21/n, a = 27.456(2), b = 13.131(1), c = 11.706(1) A, β = 91.27(1)°, Z = 4; [(Cp*Rh)2(μ-Cl)3]2[PtCl6], monoclinic, space group C2/m, a = 27.068(3), b = 11.104(1), c = 8.968(2) A, β = 101.15(2)°, Z = 2.

Determination of sulfate in brackish waters by laser Raman spectroscopy

Abstract After recent developments in our vibrational studies, we can arrive at a new method of determining sulfate in brackish waters. This paper discusses the recent developments and applications of the new method. The first thing is the establishment of a calibration work to the sulfate solutions of different concentrations using an internal standard by laser Raman spectroscopy. The second is an application of this method to the determination of sulfate in many samples of brackish waters around an estuary. The calibration curve of sulfate ion was linear up to the concentration of 0.04 mol/dm 3 in Raman spectroscopy. Sodium chloride had no effect on this calibration curve up to the concentration of 1.0 mol/dm 3 . We then applied Raman spectroscopy to determine the sulfate concentration in brackish waters near an estuary. The concentration of sulfate in brackish waters at most of the sample points was higher in ebb tide than in flood tide except at some points. Similar tendency was found for the chloride concentration of sample solutions. The concentration ratio of sulfate to chloride was nearly equal to 0.14 at most points in the flood tide. But the ratio was found to be higher in the ebb tide.

Studies on the structure of the paramagnetic μ-oxo dimer of molybdenum(V) in hydrochloric acid solutions by exafs

Abstract X-ray absorption spectra for molybdenum(V) in hydrochloric acid solutions were measured and their XANES and EXAFS were analysed. The μ-oxo dimer of Mov was detected in 4.5–6.0 M HCl solutions. The Mo: in the dimer is 2.94–3.06 A and the Mo ;OMo angle is ca 104–111°.

FT-IR measurements of some greenhouse gases in thin film of poly(methyl methacrylate)

Abstract In order to investigate specific behavior of some greenhouse gases in a vacuum desiccator, the desorption process of CO 2 , N 2 O or H 2 O from a thin film of poly(methyl methacrylate) (PMMA) was mainly followed by FT-IR method. Water molecules desorb rapidly in 3 h and N 2 O gas in 12 h, while a longer time of 72 h was needed to desorb CO 2 gas from a thin film of PMMA. We obtained new infrared data for CO 2 , N 2 O and H 2 O sorbed in PMMA film. An additional shoulder at 3420 cm −1 besides two peaks at 3630 and 3550 cm −1 was observed in the IR spectra of the water species sorbed in PMMA. Species of N 2 O in PMMA has a peak at 2223 cm −1 , which is same as one in the gas phase. Since two types of desorption, rapid and slow, were observed in the case of CO 2 two kinds of physisorbed species were present in thin film of PMMA. The peak at 2338 cm −1 is the species strongly sorbed while the peak at 2336 cm −1 and the shoulder near 2365 and 2315 cm −1 are the species weakly sorbed.

Extraction of molybdenum(VI) from aqueous solution by donor solvents

Abstract Molybdenum(VI) has been mainly extracted with chelating reagents by nonpolar solvents due to difficulties with polar solvents such as alcohols, ethers and esters. However, the coordinative donor solvents propylene carbonate, cyclohexanone and tri-n-butyl phosphate did extract molybdate albeit slowly. Each of the extracted species was identified to be hexamolybdate by the use of Raman spectroscopy. The extraction equilibrium involving cyclohexanone indicated that the main extracted species is the ion pair H′3O+(HMo6O19)− in the lower concentration of 1.0 x 10−3 M [Mo]; but both the species H′3O+(HMo6O19)− and (H3O+)2Mo6O192− are extracted in the higher concentration of molybdate (1.0 x 10−2−1.0 x 10−1 M).

Synthesis and crystal structures of palladium(II) complexes containing benzyl 8-quinolyl sulfide and phenethyl 8-quinolyl sulfide

Abstract Four palladium(II) complexes [PdX2(L-N,S)] (X=Cl, Br; L: BzSq=benzyl 8-quinolyl sulfide, PheneSq=phenethyl 8-quinolyl sulfide) were prepared. The crystal structure of [PdCl2(BzSq-N,S)] revealed the presence of an intraligand stacking between the phenyl and quinolyl groups of BzSq. This stacking interaction was confirmed even in Me2SO, MeCN and MeNO2. On the other hand, [PdCl2(PheneSq-N,S)] did not show such an intraligand stacking both in the solid and in solutions.

Surface analysis of a copper plate exposed to the ambient atmosphere by FT-IR reflection absorption spectroscopy.

海洋性気候と内陸性気候の影響下で進行する金属の腐食性を比較するため,徳島県と長野県の数か所の観測点において,銅板を大気に暴露し,定期的に試料の回収を行い,それらの腐食表面の分析を行った.銅板の表面分析には,主としてFT-IR法を用いた.その結果,両方の県の試料から,その腐食表面にニトラト,スルファト,ヒドロキソ錯体などの生成物と,Cu2OやCuOなどの表面酸化物の生成も認められた.又,いずれの試料においても,春から夏にかけて腐食反応の著しい増大が見られた.長野県の松本盆地の試料に見られる臨海型の腐食性について,風向と地形図からも検討を行ってみた.