A Redox-Switchable Single-Molecule Magnet Incorporating [Re(CN)_7]~(3+)

摘要

A variety of transition metal-oxo clusters have now been shown to exhibit slow magnetic relaxation at low temperatures. Such "single-molecule magnets" possess a high spin ground state, S, and an axial zero-field splitting, D < 0, which combine to give a relaxation barrier of U = S~2|D| if S is an integer or U = (S~2 -1/4)|D| if S is a half-integer. A parallel line of research has focused on the synthesis of high-spin metal-cyanide clusters via bridge-forming reactions between metal complexes with terminal cyanide ligands and metal complexes with suitable leaving groups. Here, the use of precursor species exhibiting orbitally degenerate electronic ground states, such as those associated with octahedral complexes of Mn~Ⅲ or low-spin Fe~Ⅲ, has often provided the magnetic anisotropy needed to create a relaxation barrier.