Synthesis of single-molecule magnets using metallocyanates

Cyanometallate building blocks are inert and stable molecules that may act as ligands towards metal complexes. A stepwise approach allows preparing polynuclear complexes with predictable architectures. The knowledge of the nature of the exchange interaction through the cyanide bridge enables chemists to reasonably predict the spin of the ground state and in some cases the magnitude of the magnetic anisotropy. During the last 10 years, hexacyanometallates led to the discovery of polynuclear complexes that behave as single-molecule magnets (SMMs). For such low-nuclearity complexes, these SMMs have a relatively high anisotropy barrier in comparison to other metaloxo-based clusters with larger spin ground state. On the other hand, the introduction of tricyanometallates led to different architectures in complexes with higher nuclearity (up to 14). Chemists took advantage of the step by step approach to introduce within the polynuclear complexes metal ions of the first or second transition metal series that have large spin-orbit coupling. All the cyanometallate clusters with such ions have been shown to behave as SMMs.