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

different atomic nuclei. Qualitative molecular orbital diagrams for both of these
compounds are shown in Figure 1-4. It should be noted however that the overall energy
of each of the orbitals will be lower in the heterocycle than in Cp - since both sulfur and
nitrogen are more electronegative than carbon.
Figure 1-4. π molecular orbitals of Cp - (left) and a generic DTDA (right) and their correlation to one
another.
The Pauling electronegativity for nitrogen is 3.08 while sulfur is only 2.58. 7 As a
result, the lowest energy π orbital, π 1 for a generic DTDA has greater electron density on
the nitrogen atoms than the sulfur atoms. This effect is carried through as we ascend the
energy scale and accounts for the loss of degeneracy for the heterocyclic analogue. The
π 4 orbital (as well as the analogous π 2 orbital) in this case, is lower in energy as it is nodal
at the carbon atom which results in a greater electron density on the more electronegative
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