Transition Metal Single-Molecule Magnets: A {Mn 31 } Nanosized Cluster with a Large Energy Barrier of ∼60 K and Magnetic Hysteresis at ∼5 K.

The first {Mn31 } cluster (1) has been prepared from carboxylate ions and the chelating/bridging ligand α-methyl-2-pyridine-methanol. Compound 1 possesses a unique nanosized structural topology with one of the largest energy barriers reported to-date for high-nuclearity 3d-metal clusters. Single-crystal magnetic hysteresis studies reveal the presence of hysteresis loops below 5 K, one of the highest temperatures below which molecular hysteresis has been observed for 3d-based SMMs.