EPR-SPECTRA OF SULFUR-33-LABELED DIMETHOXYBENZONORBORNYL THIYL FREE-RADICALS

Thiyl (1-aziridyl thiyl) radicals were prepared from benzonorbornadiene and dimethoxybenzonorbornadiene: the linewidths of the EPR spectrum of the latter were sufficiently narrow for carbon-13 satellites to be resolved. Two carbon hyperfine splitting constants were measured having values of 0.315 ± 0.002 and 0.145 ± 0.003 mT: a small splitting of 0.0318 ± 0.0003 mT from the 7-anti hydrogen was also discerned. The radical from dimethoxybenzonorbornadiene was enriched with 48.62% sulfur-33 when it was established that the radical contains only one sulfur atom; the hyperfine splitting constant of -0.277 ± 0.003 mT is consistent with the fact that the sulfur is directly bonded to nitrogen. Digital recording and data processing were used as an aid to accurate line position measurement and to spectrum analysis. © 1979.