title: End-to-end azide-bridged manganese(III) chain compounds: field-induced magnetic phase transitions and variation of T(C) to 38 K depending on the side groups of the Schiff bases.
abstract: Three one-dimensional coordination polymers [Mn(L)(N(3))](n) [L = L1 (1), L2 (2), L3 (3); L1H(2) = N,N'-bis(5-chlorosalicylideneiminato)-1,3-diaminopentane, L2H(2) = N,N'-bis(5-bromosalicylideneiminato)-1,3-diaminopentane, L3H(2) = N,N'-bis(5-bromosalicylideneiminato)-1,3-diamino-2-dimethylpropane] bridged by end-to-end azides were prepared. The crystal systems differ according to the Schiff bases used. Each Mn atom adopts a typical Jahn-Teller distortion. The helicity of the chains occurs in a racemic manner only for 2. No noncovalent forces are relevant in 2, while π-π contacts are visible in 1 and 3. Magnetic measurements show the presence of apparent spin canting. Complexes 1 and 3 exhibit a field-induced metamagnetic transition from an antiferromagnetic state to a weak ferromagnetic phase, whereas 2 embraces a field-induced two-step magnetic phase transition. The critical temperature is observed at 38 K for 2, which is relatively higher than those for 1 (11 K) and 3 (10 K). The pronounced long-range order may contribute from intrachain exchange couplings and through-space dipolar interactions between adjacent chains.
authors: Department of Chemistry, Research Institute for Natural Sciences, Korea University, Seoul 136-713, Korea.
authors: Jung Hee
authors: JH
authors: Yoon
authors: Woo Ram
authors: WR
authors: Lee
authors: Dae Won
authors: DW
authors: Ryu
authors: Jin Wuk
authors: JW
authors: Lee
authors: Sung Won
authors: SW
authors: Yoon
authors: Byoung Jin
authors: BJ
authors: Suh
authors: Hyoung Chan
authors: HC
authors: Kim
authors: Chang Seop
authors: CS
authors: Hong