title: [M(N3)2(H2O)2] x (bpeado): unusual antiferromagnetic Heisenberg chain (M = Mn) and ferromagnetic Ising chain (M = Co) with large coercivity and magnetic relaxation (bpeado = 1,2-bis(4-pyridyl)ethane-N,N'-dioxide).
abstract: We present here the structures and magnetism of two isostructural magnetic metal-azido chain compounds of the type [M(N(3))(2)(H(2)O)(2)](bpeado) (1, M = Mn; 2, M = Co; bpeado = 1,2-bis(4-pyridyl)ethane-N,N'-dioxide), prepared by utilizing the long spacer bpeado. The structure is composed of [M(N(3))(2)(H(2)O)(2)](n) metal-azido chains, in which metal ions are bridged by two end-on azido ligands, and the chains are further supported by H-bonding interactions between the coordination water of the chain and the lattice bpeado in a three-dimensional (3D) threefold interpenetrated H-bonded framework. Within the structure, the metal-azido chains are separated quite well. Investigation of the magnetic properties has revealed that the Mn compound 1 is an isotropic Heisenberg chain with unusual antiferromagnetic coupling between the Mn(2+) ions linked by double end-on azide anions. The Co compound 2 shows a strong anisotropic Ising-type ferromagnetic chain within the material. Detailed magnetic studies on both polycrystalline and single-crystal samples of 2 have revealed a large coercivity of up to 37.5 kOe (along the crystallographic b-axis), multi-magnetic transitions, and single-chain-magnet-like magnetic relaxation behavior.
authors.affiliation: Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China.
authors.forename: Hao-Ling
authors.initials: HL
authors.lastname: Sun
authors.forename: Zhe-Ming
authors.initials: ZM
authors.lastname: Wang
authors.forename: Song
authors.initials: S
authors.lastname: Gao