名称:
                                ESR studies of nitrogen-centered free radicals. 40. Exceptionally persistent nitrogen-centered free radicals. Preparation, isolation, and molecular structure of N-(arylthio)-2,4,6-triphenylanilino radicals
                             
                            
                                摘要:
                                The preparation, isolation, molecular structure, and ESR spectra of N-(arylthio)-2,4,6-triphenylanilino radicals 2 are described.  Radicals 2 have been prepared by oxidation of N-(arylthio)-2,4,6-triphenylaniline (1) with PbO2 and studied by ESR spectroscopy.  The radical solutions (benzene) were greenish blue or yellowish green, absorbing in the visible region at 513-535 and 626-644 nm.  The radicals persist over a long period with only a slight or no decomposition, even in the presence of atmospheric oxygen, and have shown no tendency to dimerize, even at low temperatures.  These properties have permitted us to isolate 2 as pure radical crystals and to determine the molecular structure of 2e by single-crystal X-ray analysis.  The ESR spectrum of 2 consists of a broad 1:1:1 triplet (alpha-N, 0.890-0.896 mT), and hyperfine splittings due to protons were completely unresolved.  However, on deuteriation of the 2,4,6-triphenyl groups on the anilino group, hyperfine splittings due to the anilino meta (0.133-0.134) and the arylthiyl ortho protons (0.088 mT) were found.  Furthermore, at high gain satellite lines due to S-33 isotopes (0.51 mT) at natural abundance were detected.  On the basis of these ESR results the spin density distribution in 2 is elucidated.