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

nitrogen atom would be very little and arise purely from spin polarization. Therefore the
exchange pathway is most likely arising from the interactions with the other sulfur atom
of one complex which is close to the nitrogen atom of the DTDA ring which bears the
majority of the spin density. Using the analytical expression of Bonner-Fisher for the
chain with the Hamiltonian defined in equation 2.5: 2 (2.5)
as well as an additional S = ½ Curie contribution from the binuclear units, the magnetic
data were fit fairly well down to 1.8 K with an antiferromagnetic coupling constant of
J/k B = -31.6(5) with g av = 2.23(5) (Figure 2-12 b).
Compounds II-7 and II-8 are the first example of a DTDA radical ligand coordinated
to a diamagnetic metal ion and therefore serve as a benchmark for analyzing the magnetic
contributions from the ligand alone without the additional magnetic contributions of the
metal ions. This could serve well for analyzing the magnetic influence of the DTDA
ligand for complexes in which the metal ions exhibit significant magnetoanisotropy such
as in the cobalt complex II-10 where the magnetic exchange of the two cobalt ions makes
it difficult to ascertain the features of the susceptibility which arise only from the
interactions of the ligand and metal spins. Also, as the mixed compound II-8 is
isomorphous to the manganese complex II-9′, 19
it could serve to shed light on the
magnetic data of this compound which, due to the influence of the two S = 5/2 Mn 2+
centers, would be substantially more convoluted.
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