Single-molecule magnets: a Mn25 complex with a record S = 51/2 spin for a molecular species.

The reaction of MnCl2.4H2O (3 equiv), pyridine-2,6-dimethanol (pdmH2) (10 equiv), and NaN3 (10 equiv) in MeOH/MeCN (1:2 v/v) with NMe4OH (1 equiv) gave [Mn25O18(OH)2(N3)12(pdm)6(pdmH)6](Cl)2.12MeCN (1.12MeCN) in approximately 30% yield. The cation of complex 1 comprises five Mnx layers of three types in an ABCBA arrangement. Fitting of variable-temperature and -field magnetization data establishes that 1 has an S = 51/2 ground state, the largest value for a molecular species. The complex also displays hysteresis loops below 0.6 K in magnetization vs applied field sweeps, establishing it as the largest spin single-molecule magnet to date.