title: Magnetic systems with mixed carboxylate and azide bridges: slow relaxation in Co(II) metamagnet and spin frustration in Mn(II) compound.
abstract: Two coordination polymers formulated as [{[Co(2)(L)(N(3))(4)]·2DMF}(n) (1) and [Mn(2)(L)(H(2)O)(0.5)(N(3))(8)](n) (2) (L = 1,4-bis(4-carboxylatopyridinium-1-methyl)benzene) were synthesized and structurally and magnetically characterized. In compound 1, the anionic uniform Co(II) chains with mixed (μ-EO-N(3))(2)(μ-COO) triple bridges (EO = end-on) are cross-linked by the cationic bis(pyridinium) spacers to generate 2D coordination layers. It was demonstrated that the triple bridges mediate ferromagnetic coupling and that the compound represents a new example of the rare systems exhibiting the coexistence of antiferromagnetic ordering, metamagnetism, and slow magnetic dynamics. Compound 2 features the magnetic Δ-chain formed from isosceles triangular units with single μ-EE-N(3) and double (μ-EO-N(3))(μ-COO) bridges (EE = end-to-end). The Δ-chains are interlinked by long organic ligands into a 3D framework with novel net topology and 3-fold interpenetration. The magnetic properties of 2 indicate the presence of spin frustration characteristic of Δ-chains with antiferromagnetic interactions.
authors.affiliation: Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, East China Normal University, Shanghai 200062, People's Republic of China.
authors.forename: Yan-Qin
authors.initials: YQ
authors.lastname: Wang
authors.forename: Xiu-Mei
authors.initials: XM
authors.lastname: Zhang
authors.forename: Xiu-Bing
authors.initials: XB
authors.lastname: Li
authors.forename: Bing-Wu
authors.initials: BW
authors.lastname: Wang
authors.forename: En-Qing
authors.initials: EQ
authors.lastname: Gao