Abstract
Five persistent radicals 1a-1e were generated by the oxidation of 4H-[1,2,4]thiadiazines 2a-2e and studied with ESR and UV-vis spectroscopy. Three of the radicals, 1a, 1d, and 1e, were generated in high yields (>90%) using either SO2Cl2/amine in toluene or AgO/K2CO 3 in a toluene/ MeCN mixture. Halogenated radicals 1d and 1e were sufficiently stable for chromatographic isolation and vacuum sublimation. The solution stability of the fluorinated 1d was measured at t1/2 ≈ 4 months in the absence of oxygen, and 1e at t1/2 ≈ 40 min in the presence of air. The crystal and molecular structures of 1d were determined by X-ray crystallography showing columns of parallel almost evenly spaced planar heterocycles connected by infinite ⋯N⋯S⋯ chains. Cyclic voltammetry of Id and 1e shows reversible reduction waves at about 0 V and irreversible oxidations at about 1.2 V. Spectral and electrochemical properties of 1 were well reproduced by DFT methods.
Original language | English (US) |
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Pages (from-to) | 7525-7536 |
Number of pages | 12 |
Journal | Journal of Organic Chemistry |
Volume | 69 |
Issue number | 22 |
DOIs | |
State | Published - Oct 29 2004 |