- High-pressure responses of alkali metal hydrogen carbonates, RbHCO3 and CsHCO3: Findings of new phases and unique compressional behavior
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High-pressure responses of RbHCO3 and CsHCO3 were characterized by in situ Raman spectroscopy and X-ray and neutron diffraction observations. RbHCO3 exhibited a monoclinic (phase IV) and a triclinic (phase V) high-pressure phase at ~0.5 ?GPa and room temperature. Increasing compression induced unique behavior in a specific cell parameter (a in phase IV or c in phase V), which first increased, and then decreased at ~1 ?GPa, likely owing to the rearrangement of Rb+ and reconfiguration of the ordered (HCO3 ?)2 dimers. Deuterium positions in phase IV of RbDCO3 were determined. The hydrogen bonding remained moderately strong, and possibly did not affect the phase transition despite the accompanying disordering and ordering of the dimers. CsHCO3 showed no structural change up to 5 ?GPa, suggesting that its ambient phase (isostructural to phase IV of KHCO3) was already stable at high pressure. The structural stability appeared to be systematically related to the cation size.
- Iizuka-Oku, Riko,Gui, Weibin,Komatsu, Kazuki,Yagi, Takehiko,Kagi, Hiroyuki
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- The Alkali Metal Salts of Methyl Xanthic Acid
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Methyl xanthates of the type M(SSC-OMe) (M = Li–Cs) are readily formed when carbon disulfide is reacted with the corresponding alkali metal hydroxides in methanol exposed to air, or with the alkali metal methoxides in dry methanol or THF under exclusion of air. The reactions are easily monitored by 13C NMR spectroscopy. The Na, K, Rb, and Cs salt could be isolated in high yields, while the Li salt decomposed upon attempted isolation. All compounds are readily complexed by crown ethers and form isolable 1:1 adducts, including the elusive Li salt. All products were studied by NMR (1H, 13C, and alkali metal nuclei) and IR spectroscopy, and most of them where structurally characterized by single-crystal X-ray diffraction. Li(SSC-OMe)(12c4) (12c4 = [12]crown-4) and Cs(SSC-OMe)(18c6) (18c6 = [18]crown-6) represent the first structurally characterized lithium and caesium xanthate complexes, respectively.
- Liebing, Phil,Schmeide, Marten,Kühling, Marcel,Witzorke, Juliane
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p. 2428 - 2434
(2020/06/17)
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- Novel Synthesis of Oxalate from Carbon Dioxide and Carbon Monoxide in the Presence of Caesium Carbonate
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In the presence of caesium carbonate 1, the direct reaction of CO2 (110 atm) with CO (20 atm) results in reductive capture of CO2 to give caesium oxalate 2 in good yield at elevated temperature (380 deg C).
- Kudo, Kiyoshi,Ikoma, Futoshi,Mori, Sadayuki,Komatsu, Koichi,Sugita, Nobuyuki
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p. 633 - 634
(2007/10/02)
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