ENDOR and triple resonance studies of 1,4-dihydro-1,2,4-benzotriazinyl radicals and 1,4-dihydro-1,2,4-benzotriazine radical cations

✍ Scribed by Franz A. Neugebauer; Gösta Rimmler

• Publisher: John Wiley and Sons
• Year: 1988
• Tongue: English
• Weight: 395 KB
• Volume: 26
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1260260712

✦ Synopsis

ESR, ENDOR and triple resonance studies of 1,4-dihydro-1,3-diphenyl-(la) and 3-tert-butyl-1,4dihydro-lphenyl-l,2,4benzotriazinyl (2a) and of the corresponding radical cation 3a (2a protonated at N-4) yielded the magnitude and the sign of almost all of the 'H and I4N hyperfine coupling (HFC) constants. Their assignment was performed using various *H labelled and/or methyl substituted derivatives. Both radical groups show major hyperfine coupling to the three 14N nuclei. In the uncharged species l a and 2a, the spin density at N-4 apparently directs the 'H HFC pattern in the 1,2,4benzotriazinyl component, a(H-5) and u(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 'H HFC pattern, a(H-6) and a(H-8) being larger than a(H-7).