A single-chain magnet with a very high blocking temperature and a strong coercive field.

Two isostructural 1D complexes, [M(hfac)2NaphNN]n [M = Mn(II) (1) or Co(II) (2); NaphNN = 1-naphthyl nitronylnitroxide], were synthesized and exhibit very strong antiferromagnetic metal-radical exchange coupling. Compound 2 shows slow magnetic relaxation behavior with a high blocking temperature (TB ≈ 13.2 K) and a very high coercive field of 49 kOe at 4.0 K.