Manganese carboxylate clusters: from structural aesthetics to single-molecule magnets

An overview is provided of some recent developments in manganese carboxylate cluster chemistry. A variety of synthetic methodologies are described together with the structures of the resultant products, which span metal nuclearities of 4 to 18 and oxidation states of II to IV, including mixed-valency. The spins of the ground states of these products are often large and sometimes abnormally large, and in certain cases when this is coupled to a sufficiently large magnetoanisotropy, the dusters function as single-molecule magnets i.e., they can be magnetized by an external magnetic field below a critical temperature. These complexes display hysteresis in magnetization vs, magnetic field studies, and clear evidence for quantum tunnelling of magnetization. Such results establish single-molecule magnetism as a new magnetic phenomenon, and one that holds great promise for next-century technological applications. (C) 1998 Elsevier Science Ltd. All rights reserved.