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

catecholate from Figure 3-7) was not stable in a protic medium or in a bulk solution of
the radical.
It was postulated that substituting the proton for an R group would make this
oxidation state accessible and thus provide an opportunity to take advantage of the
anionic properties as a good donor for coordination as well as the unpaired electron to
facilitate magnetic coupling between the metal and ligand. Several compounds were
investigated and it was found that the synthesis for III-3 was the most facile and pure
sample was easily obtainable. A number of methylating agents were employed in the
attempt to isolate III-4 from III-1 with a base such as those derived from the counterions
listed above, but these were met with limited success. The addition of the base often
proceeded to initiate a dramatic colour change from the red solution obtained from III-1
to a dark colour of the anionic compound which varied depending on the counterion,
ranging from a dark blue (lithium) to a greenish blue (sodium) or purple
(triethylammonium). A colour change occurred very quickly and so after only a short
duration the methylating agent was added. Several reagents were employed such as
methyl iodide, Meerwein’s salt and methyl triflate. It should be noted that these, as well
as most other methylating agents, are extremely carcinogenic and should be handled with
care and respect.
It was found that when organic bases were used such as triethylamine or similar
compounds, methylation would preferentially take place on the base itself, yielding
methyl triethylammonium, counter balanced by the anion produced by the methylating
agent. This usually precipitated from solution as a powder and the filtrate was found to
contain the starting material III-1. When III-2 was employed as the intermediate it was
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