Crossover between Three-Dimensional Antiferromagnetic and Ferromagnetic States in Co(II)Cu(II) Ferrimagnetic Chain Compounds. A New Molecular-Based Magnet with Tc = 38 K and a Coercive Field of 5.66 × 103 Oe

Abstract

CoCu(pbaOH)(H2O)3·2H2O (1) is a Co(II)Cu(II) chain compound in which the ferrimagnetic chains interact antiferromagnetically within the lattice. Removing the two noncoordinated water molecules through a thermal treatment results in the new chain compound CoCu(pbaOH)(H2O)3 (2) which exhibits a ferromagnetic ordering of the ferrimagnetic chains at Tc = 9.5 K. Removing a third water molecule, occupying the apical position in the copper coordination sphere, results in CoCu(pbaOH)(H2O)2 (3) which again exhibits a three-dimensional ferromagnetic ordering, but at Tc = 38 K. The field dependence of the magnetization for 3 reveals a coercive field of 5.66 × 103 Oe at 2 K, probably a record in the field of molecular-based magnets. This dehydration process giving rise to a crossover between long-range antiferro- and ferromagnetic states is reversible, and can be repeated.