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

ing was formed. One of the nitrogen atoms in this second TDA moiety actually formed a
third bond to bridge two 6-membered carbon rings. A sulfur atom positioned ortho to the
bridging nitrogen atom also formed a bridging interaction with the other ring.
This crystal structure is shown in Figure 5-6. The R value for this compound was found
to be 6.01% and therefore the identities of the chlorine atoms on the cation are less in
question. Important crystallographic parameters for these two compounds are outlined in
table 5-1.
5.2.5 EPR Spectroscopy
Despite not obtaining a purified product we were able to obtain an EPR spectrum of
what is believed to be V-1. The spectra obtained from full scale reductions of any of the
precursor salts were usually low intensity and poorly defined, especially from reactions
using V-3 or V-4. Higher quality data were obtained from performing the reduction in
situ, using an EPR tube with a wide reservoir outside of the narrow quartz tube which is
inserted into the instrument. The spectrum shown in Figure 5-7 was obtained from V-3,
using triphenyl antimony as the reducing agent in methylene chloride which was added
under argon before the cell was sealed with a rotoflo to ensure an inert atmosphere. The
portion of the signal on the far right of the spectrum is not as well resolved as the portion
on the left, arising from slow tumbling of the radical in solution. The experimental
spectrum appears at the top and it can be seen that the primary signal has been split into
three separate lines and each of the these have been split further for a total of 7 lines. As
14 N has a nuclear spin of 1, the three primary lines of the spectrum are from strong
coupling to one of the nitrogen atoms in the molecule. This is most likely the nitrogen
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