Showing papers by "Chizuko Kabuto published in 1999"

Synthesis and structure of a stable cyclic dialkylgermylene

Abstract: A stable cyclic dialkylgermylene (1) was synthesized by reductive dechlorination of the corresponding dichlorogermane (6) with sodium. Germylene 1 is monomeric both in solution and in the solid state, as observed by UV-vis spectroscopy and X-ray crystallography.

Coordination of epithio groups of p-tert-butylthiacalix[4]arene in a Zn2+ complex studied by X-ray crystallography

Abstract: Single-crystal X-ray analysis has shown that p-tert-butylthiacalix[4]arene (H4L) binds to Zn2+ ion by bridging sulfur atoms in addition to phenolic oxygen atoms to form [Zn4L(H2L)2].

Convenient Synthesis of Chiral Cyclophanes that Can Coordinate to Metals

Abstract: Optically pure cyclophanes possessing a 1,3-dicarbonyl moiety were conveniently synthesized from alkanedioyl dichloride in four steps. The intramolecular [4+2]cycloaddition of bis(acylketene)s generated by thermal decomposition of bis(4,6-dioxo-1,3-dioxane) proceeded smoothly, giving cyclophane pyranones in high yields. The compounds possessing 7−10 bridging methylenes were resolved by imine formation with (R)-1-phenylethylamine, followed by basic hydrolysis. These cyclophanes are optically active versions of acetylacetone or salicylaldehyde and formed complexes with metals such as copper and europium. X-ray analysis of the chiral copper complex indicated the pentacoordinated structure of the copper metal with syn configuration of the two bridging chains.

Formation of Kinetically Stabilized Dithiiranes by Treating Thione S-Oxides Bearing a Bulky Substituent with Lawesson's Reagent.

Abstract: Treatment of sterically crowded thione S-oxides derived from d-camphor with Lawesson’s reagent afforded dithiiranes along with deoxygenation of the starting materials, and the mixtures were subjected to mCPBA oxidation to give the corresponding dithiirane S-oxides and thione S-oxides.

An ESR Study of a Tetrasilaspirobiindane Anion Radical. Stereoelectronic Electron - Accepting Effects of Trialkylsilyl Groups

Abstract: ESR spectra of a tetrasilaspirobiindane anion radical (1−) showed a doublet of doublet hfs pattern at low temperatures and significant line-width alternation, indicating that there is remarkable difference in the electron-accepting effects between two silyl substituents at the benzene ring with the unpaired electron due to the ring conformation.

X-Ray Crystal Structure and Dynamic Behavior of Pentafluoro-9,10-disila-9,10-dihydroanthracene Anion Salts Having Transannular 1,4-Fluorine Bridge

Abstract: Potasium-18-crown-6 and tetraethylammonium ion salts of pentafluoro-9,10-disila-9,10-dihydroanthracene anion (5a and 5b) have an unsymmetrical transannular 1,4-fluorine bridge in the solid states. In solution, 5a and 5b show a facile intramolecular fluorine exchange.

Synthesis and Structure of a Stable Cyclic Dialkylgermylene.

Abstract: A stable cyclic dialkylgermylene (1) was synthesized by reductive dechlorination of the corresponding dichlorogermane (6) with sodium. Germylene 1 is monomeric both in solution and in the solid state, as observed by UV-vis spectroscopy and X-ray crystallography.

Formation of Kinetically Stabilized Dithiiranes by Treating Thione S‐Oxides Bearing a Bulky Substituent with Lawesson′s Reagent.

Abstract: Treatment of sterically crowded thione S-oxides derived from d-camphor with Lawesson’s reagent afforded dithiiranes along with deoxygenation of the starting materials, and the mixtures were subjected to mCPBA oxidation to give the corresponding dithiirane S-oxides and thione S-oxides.