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

attributed to the higher degree of spin-orbit coupling expected for the heavier selenium
atoms in this species when compared to the sulfur analogues. 9 The spectrum for II-1 is
shown in Figure 2-2 a.
The binuclear zinc complex II-7 was also analyzed via EPR spectroscopy by creating
a very dilute solution of the compound in methylene chloride such that the solution
possessed no discernible colour. The spectrum is very similar to II-2 such that it is a
simple 5-line pattern with intensity ratios of approximately1:2:3:2:1, indicating coupling
to 2 equivalent nitrogen atoms. There are however several differences between the two
spectra. The first is that the nitrogen coupling constant for II-7 (a N = 4.82 G) is smaller
than that observed for II-2 (a N = 5.12 G), suggesting that spin density is delocalized away
from the N atoms. Also, the g value for the metal complex (g = 2.038) is increased when
compared to the value for the uncoordinated radical (g = 2.010). 3
Interestingly the
increase in the g-shift is approximately the same for pymDSDA (g = 2.0382).
a b c
Figure 2-2. EPR spectra of a) II-1, g = 2.0382, b) II-7, a N = 4.82, g = 2.038 and c) II-2 a N = 5.12,
g = 2.010.
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