One-Dimensional End-To-End Azide-Bridged Mn-III Complexes Incorporating Alkali Metal Ions: Slow Magnetic Relaxations and Metamagnetism

Abstract

Three azide-bridged Mn-III chains [Mn(3-MeOsalpn)(N-3)]center dot 0.5AClO(4) (A = Na (1), K (2), Rb (3); 3-MeOsalpn = N,N'-propylenebis(3-methoxysalicylideneiminato) dianion) incorporating alkali metal ions and perchlorate anions were systematically synthesized. The overall structure can be described as a one-dimensional chain bridged by end-to-end azide ligands, although spatial arrangements of Jahn-Teller axes of Mn in 1 and 2 are different from that in 3. Relying on the alkali metal ions, magnetic properties are varied from a two-step phase transition (1) to metamagnetic transitions (2 and 3). In this system, spin canting definitely plays a central role in giving rise to the apparent slow magnetic relaxations in 1 and 2 because application of a high external magnetic field tends to destroy single-chain magnet (SCM) properties. Despite the existence of a long-range antiferromagnetic order at T-N, slow magnetic relaxation is notably observed in 2, which likely emanates from the operative spin canting below T-N.