ORIGIN OF THE HYPERFINE ANISOTROPY IN A MN(IV) COMPLEX CONTAINING PARAMAGNETIC LIGANDS

The electronic structure of the manganese complex of the Schiff base, 1-(2-oxo-3,5-di-tertbutyl-3,6-cyclohexadiene)imine radical (SQ-N-BQ; m onoanionic form = Cat-N-BQ; dianionic form = Cat-N-SQ) is re-examined on the basis of single-crystal EPR studies on Mn/Zn(dat N-BQ)(2). It i s shown that both possibilities, viz. Mn(Cat-N-BQ)(2) (low-spin Mn2+) and Mn(Cat-N-SQ)(2) (Mn4+, strongly antiferromagnetically coupled with two S = 1/2 ligands) can have an anisotropic manganese hyperfine coup ling, albeit for different reasons.