Molecular magnets - Hybrid organic-inorganic layered compounds with very long-range ferromagnetism

The correlations between structures and magnetic properties of new hybrid layered compounds M-2(OH)(3)X (M = Co or Cu), where X is an exchangeable organic anion, are investigated. When the anion is a simple spacer (aliphatic chain), ferromagnetic in-plane interactions dominate, and the situation depends to a large extent on the interlayer spacing d. For small spacings (d < 10 Angstrom), 3D antiferromagnetic order is stabilized, while large spacings favor spontaneous magnetization, even for d approximate to 40 Angstrom, due to dipolar through-space interactions. When X is a radical anion, new metal-radical magnets, with d close to 20 Angstrom, are achieved. Strong interactions between the 3d and pi electrons are evidenced, and a net magnetic moment occurs at low temperature. Such compounds are promising for the design of new molecular multiproperty materials. (C) 1998 Elsevier Science S.A. All rights reserved.