1,2,3-Dithiazolyl and 1,2,35-Dithiadiazolyl Radicals as Spin-Bearing ...

hydrogen bonding with a polar solvent in that it is much broader than the other peaks in
the spectrum. The other four signals have the same coupling patterns as those observed
for V-15, except that they have shifted substantially.
Figure 5-19. 1 H NMR spectrum of V-16 at 300 MHz in d 6 -DMSO.
The aromatic signal farthest downfield is now the doublet with the larger of the two
coupling constants at 7.40 ppm and corresponds to the proton meta to the ammonium
substituent, while the singlet corresponding to the proton adjacent to the carbon-carbon
dimerization linkage has shifted to a value of 7.47 indicating that it is more deshielded in
V-16 than in V-15. Continuing to move downfield, the next signal that appears is a
doublet of doublets which, just like in V-15, corresponds to the proton directly adjacent
to the ammonium group in a counter-clockwise direction, with the larger of the coupling
constants corresponding to the proton directly adjacent, while the smaller corresponds to
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