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

2.2.2 pymDSDA Coordination Complexes
The syntheses of [Ni(hfac 2 ) 2 ]·pymDSDA (II-5) and [Mn(hfac 2 ) 2 ]·pymDSDA (II-6)
were carried out in a similar fashion to that of the pymDTDA coordination complexes 3
except that the solubility of the selenium-based radical was much lower than the sulfurbased
analogue. The amount of solvent that was required to achieve complete
homogeneity of the radical solution in methylene chloride was a factor of 10 greater for
II-1 than for II-2. In a typical reaction, the methylene chloride was distilled directly
from CaH 2 into a side-arm-round-bottom-flask containing crystalline II-1. This solution
was a dark yellow/golden colour, in sharp contrast to the deep violet colour observed for
an analogous solution of II-2. For a typical 100 mg reaction scale of II-1, approximately
300 mL of solvent was required. Due to the high molecular weights associated with the
metal containing precursors, and the fact that 2 molar equivalents were necessary to
achieve the correct reaction stoichiometry, a substantial quantity of the metal containing
material was required (usually on the order of 350-450 mg for 100 mg of radical).
However the hfac ligands greatly enhance the solubility of these metal containing starting
materials such that usually only 20-30 mL of methylene chloride were required to
achieve complete homogeneity. After both solutions were prepared, the solution
containing the M(hfac) 2·2THF was added to the solution of pymDSDA, resulting in an
immediate colour change. This reaction is outlined in scheme 2-2.
The reaction mixtures were allowed to stir at room temperature for one half an hour,
although usually no further change was observed. The resulting coordination complexes
are also usually quite soluble in methylene chloride resulting in a completely
homogeneous solution, so the solvent must then be removed by flash distillation to
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