In an effort to study the magnetostructural correlations in exchange c
oupled dimers, an attempt has been made to calculate the isotropic exc
hange using the molecular orbitals of unpaired electrons from extended
Huckel theory methods. Calculation of the total isotropic exchange in
a variety of Ni(III) dithiolene complexes is presented. Using the pro
grams developed to obtain the antiferromagnetic and ferromagnetic cont
ributions to the total exchange, various model systems have also been
studied in order to get a good understanding of the variations of the
two individual contributions with structural changes.