ORGN 171 |
Experimental and theoretical investigations of fused-ring thiadiazinyl radicals
| Piotr Kaszynski1, Jozef Zienkiewicz1, and Victor G. Young Jr.2. (1) Department of Chemistry, Vanderbilt University, Nashville, TN 37235, (2) Chemistry Department, University of Minnesota, 207 Pleasant St. S.E, Minneapolis, MN 55455 |
Five persistent radicals 1a-1e were generated by the oxidation of the corresponding 4H-[1,2,4]thiadiazines, and studied with ESR and UV-vis spectroscopy. Three of the radicals 1a, 1d and 1e were generated in high yields (>95%), while the pyridio and pyrazino radicals 1b and 1c were generated in lower yields (~45% and <10%, respectively). Only the halogenated derivatives 1d and 1e showed marked stability and were isolated using chromatography and vacuum sublimation. Their crystal and molecular structures were determined by X-ray crystallography. Cyclic voltametry revealed a redox window of about 1.2 V and an irreversible oxidation at about 1.0 V. The heterocycles 1d and 1e are investigated further as structural elements of liquid crystalline radicals.  |
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