Generation, Isolation, ESR and 1H ENDOR Spectra, and Magnetic Characterization of N-[(4-Nitrophenyl)thio]-2-t-butyl-1-pyrenylaminyl

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Abstract
The oxidation of N-[(4-nitrophenyl)thio]-2-t-butyl-1-aminopyrene yielded a quite persistent and oxygen-insensitive N-[(4-nitrophenyl)thio]-2-t-butyl-1-pyrenylaminy radical (3), which was isolated as reddish-black fine needles. The hyperfine coupling (hfc) constants for the aminyl were determined by ESR and 1H ENDOR measurements, indicating that there is an extensive delocalization of the unpaired electron from the nitrogen onto the pyrene ring. A comparison of the hfc constants with structurally close N-[(4-nitrophenyl)thio]-7-t-butyl-1-pyrenylaminyl (1) and N-[(4-nitrophenyl)thio]-2,7-di-t-butyl-1-pyrenylaminyl (2) showed that although the spin-density distribution of 3 is similar to that of 2, it is greatly different from that of 1. Magnetic susceptibility measurements of 3 in solid radical crystals showed that the magnetic interaction between the radical spins is strongly antiferromagnetic, giving J/k = −108 and −192 K for 2 and 3, respectively.