(H2mela)2[FeCl5]Cl (mela = melamine): A Cl-bridged single-chain magnet based on weak ferromagnetism

Presented here are the structures and magnetism of two isostructural magnetic Cl-bridged chain compounds of the type (H2mela)2[MCl5]Cl (melamelamine, MFe(II) (1), MMn(II) (2)). The chain structure is formed along the Jahn–Teller elongation axis of the MCl6 octahedra. In compound 1, the Cl− ion transmits an antiferromagnetic exchange interaction that, combined with the magnetic anisotropy of the Fe(II) sites, gives rise to a canted antiferromagnetic arrangement of the spins. Detailed magnetic studies revealed that 1 exhibits slow magnetic relaxation behavior like single-chain magnet (SCM), and that the finite size effects, due to naturally occurring defects, strongly influences the static and dynamic properties of 1. The contribution of the correlation length to the energy barrier has also been investigated.The Mn compound 2 is an isotropic Heisenberg chain with antiferromagnetic coupling between the Mn(II) ions. Doped crystals of Zn1, Cu1–Cu5 and Mn1–Mn5 were synthesized by introducing different contents of Zn(II), Cu(II) and Mn(II) ions to study the magnetic dilution and decoupling phenomena, respectively.

► A spin-canted chain shows Glauber-like dynamics at the low temperatures.
► It is a Heisenberg SCM with a crossover to finite chain dynamics occurs below 2.4 K.
► The Cl− bridged Fe2+ into a chain and transmitted strong antiferromagnetic coupling.
► Magnetic dilution and decoupling phenomena of the SCM chain were studied.