Premium
ENDOR and triple resonance studies of 1,4‐dihydro‐1,2,4‐benzotriazinyl radicals and 1,4‐dihydro‐1,2,4‐benzotriazine radical cations
Author(s) -
Neugebauer Franz A.,
Rimmler Gösta
Publication year - 1988
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260260712
Subject(s) - chemistry , radical , hyperfine structure , protonation , hyperfine coupling , spin density , electron paramagnetic resonance , resonance (particle physics) , radical ion , coupling constant , nuclear magnetic resonance , crystallography , medicinal chemistry , ion , atomic physics , organic chemistry , physics , condensed matter physics , particle physics
ESR, ENDOR and triple resonance studies of 1,4‐dihydro‐1,3‐diphenyl‐ (1a) and 3‐ tert ‐butyl‐1,4‐dihydro‐1‐phenyl‐1,2,4‐benzotriazinyl (2a) and of the corresponding radical cation 3a (2a protonated at N‐4) yielded the magnitude and the sign of almost all of the 1 H and 14 N hyperfine coupling (HFC) constants. Their assignment was performed using various 2 H labelled and/or methyl substituted derivatives. Both radical groups show major hyperfine coupling to the three 14 N nuclei. In the uncharged species 1a and 2a, the spin density at N‐4 apparently directs the 1 H HFC pattern in the 1,2,4‐benzotriazinyl component, a (H‐5) and a (H‐7) being larger than a (H‐6) and a (H‐8). In the radical cation, on the other hand, N‐1, with an unusually large splitting of 9.9 G, is the position of highest spin density which determines the 1 H HFC pattern, a (H‐6) and a (H‐8) being larger than a (H‐7).