EFFECTS OF ALTERNATION IN SOME QUASI-ONE-DIMENSIONAL MAGNETIC-MATERIALS

Abstract

Exchange coupling in Cu(II) and Mn(III) compounds with unusual structures is discussed. {[Cu(bipyrimidine)(OH)(H 2O)] (ClO 4)} n has an alternatingly bridged structure with alternating ferromagnetic (+167.6 cm -1 through the hydroxo bridge) and antiferromagnetic (-79.8 cm -1 through the bipyrimidine bridge) interactions. Copper(II) phthalate monohydrate has alternating next-nearest-neighbor exchange with J=-12.3 cm -1 and α=0.06. This is the first member of this class. The compound K 2[Mn(III) (salicylate) 2][Mn(III) (salicylate) 2]{CH 3OH] 2 has manganese ions in two environments alternating along the chain. A modified model for the chain is presented, and exchange coupling is found to be small since magnetic orbitals are not linked by the bridging ligand.