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

such as ferrocene or related compounds. 109
The choice of reagent depends on the
reduction potential which can been determined electrochemically. 110
The SOMO for this radical is similar to that for the 1,2,3,5-DTDAs already discussed
which places some electron density on one of the carbon atoms. 109 The result is that any
substituent on this carbon atom will also have some spin density either from expanding
the SOMO over a larger molecular area or through spin polarization.
Figure 1-11. Generic 1,2,3-DTA ring illustrating the positions of the respective atoms (left) and the
SOMO for the 1,2,3-ring with a node at the carbon adjacent to the nitrogen (right).
The compound 2,5-dichloro-1,2,3-dithiazolium chloride, also known as Appel’s salt
(I-17a) 132 was doubly reduced to afford the a carbon-carbon bridged dimer (1-17b) and
the radical (I-17c), a presumed intermediate, was not detected by EPR spectroscopy
likely because the association and subsequent reduction occur too quickly. 111,112 The
benzo-fused DTA systems are therefore much more interesting as their connection to the
Scheme 1-3. Double reduction of I-17a to give I-17b.
I-17c
32