Isolation and Ambident Reactivity of a Chlorogermylenoid

Treatment of 2,5‐di(3,5‐tert‐butylphenyl)‐1‐lithioferrocene with GeCl₂?dioxane afforded the corresponding chlorogermylenoid that exhibited an ambident reactivity in different solvents; it displayed a behavior characteristic for a dichlorogermylene anion in THF, while it exhibited the typical reactivity of a chlorogermylene in toluene. X‐Ray diffraction analysis of a single crystal of this chlorogermylenoid, obtained from recrystallization in THF, revealed a separated‐ion‐pair structure in the solid state.     

Thermal Stability of Oxidized Single‐Walled Carbon Nanotubes: Competitive Elimination and Decomposition Reaction Depending on the Degree of Functionalization

The thermal stability of oxidized single‐walled carbon nanotubes (SWNTs) with various degrees of oxidation was investigated. The oxidized SWNTs exhibited lower absorption and radial breathing mode (RBM) peaks and a higher intensity ratio of the D band to the G band (D/G) in their absorption and Raman spectra than those of the pristine SWNTs. After the thermal treatment, the D/G ratio of the oxidized SWNTs almost recovered its original intensity, regardless of the degree of oxidation. The absorption, photoluminescence (PL), and RBM peaks could not recover their original intensities when the oxidation degree was high. The results indicate that the elimination and decomposition reactions proceeded competitively depending on the degree of oxidation. In addition, a new PL peak was observed in the near‐infrared region, and the PL peak intensity increased with the subsequent thermal treatment. The theoretical calculations provided an insight into the possible pathways for the decomposition of oxidized SWNTs, showing that the O₂ elimination and CO/CO₂ evolution proceed competitively during thermal treatment.     

Convenient synthesis of oxazolidinones by the use of halomethyloxirane, primary amine, and carbonate salt

[reaction: see text] Primary amines reacted with carbonate salts (Na2CO3, K2CO3, Cs2CO3, and Ag2CO3) and halomethyloxiranes in the presence of a base such as DBU or TEA to give oxazolidinones in high yields. The use of K2CO3 among these carbonate gave the best yield in this synthesis. A reaction mechanism was proposed that the oxazolidinone was obtained from an oxazinanone intermediate via a bicyclo[2.2.1] intermediate. The present reaction can be widely applied to convenient synthesis of useful N-substituted oxazolidinones and chiral oxazolidinones.     

Sc3N@C80: computations on the two-isomer equilibrium at high temperatures.

Reported herein are computations on the relative concentrations of the two experimentally known isomers of Sc3N@C80 , that is, those produced by encapsulation of Sc3N in two particular C80 cages that obey the isolated-pentagon rule, namely, with I(h) and D(5h) symmetries. The calculations are based on density functional methods and have been carried out using the Gibbs energy over a broad temperature interval. It has been computed that, if a relatively free motion of the encapsulate inside the cages is allowed, the observed populations of 10 and 17 % for the D(5h) Sc3N@C80 species are reached at temperatures of 2100 and 2450 K, respectively. The inclusion of the entropy term is essential as, if it is neglected, the D(5h) Sc3N@C80 population at a temperature of 2100 K would be a mere 1 %, owing to the relatively large interisomeric separation potential energy of 19 kcal mol(-1).     

Relationship between Hemolytic Toxicity and Signal Intensity of Various Organotin Compounds by a Spin-labeling Technique

Various organotin compounds caused strong hemolysis of erythrocytes. To investigate the mechanism of hemolysis, spin-labeling techniques with electron spin resonance (ESR) spectroscopy were used and the relationship between hemolytic toxicity and signal intensity was investigated. Two kinds of spin-labeled stearic acid in which the para- magnetic center was located at different sites on the alkyl chain (5- and 12-doxyl-stearic acids; 5- and 12-NS) were used. It became clear that the decrease of ESR signal intensity was related to the hemolytic toxicity of the organotin compounds. © 1997 by John Wiley & Sons, Ltd.