title: Structures and magnetism of azide- and carboxylate-bridged metal(II) systems derived from 1,2-bis(N-carboxymethyl-4-pyridinio)ethane.
abstract: Four coordination polymers of different transition metal ions with azide and the zwitterionic dicarboxylate ligand 1,2-bis(N-carboxymethyl-4-pyridinio)ethane (bcpe) were synthesized, and structurally and magnetically characterized. They are formulated as [M(2)(bcpe)(N(3))(4)].H(2)O (M = Mn, 1; Co, 2; and Ni, 3) and [Cu(3)(bcpe)(N(3))(6)].(H(2)O)(2) (4). In the isomorphous compounds , octahedral metal ions are linked by the mixed (micro(2)-syn,syn-COO)(mu(2)-EO-N(3))(2) triple bridges (EO = end-on) to give anionic uniform chains, which are cross-linked by the cationic bis(pyridinium) spacers to produce two-dimensional coordination layers. Magnetic studies demonstrated that the magnetic coupling through the mixed triple bridge is antiferromagnetic in the Mn(ii) compound (1) but ferromagnetic in the Co(ii) and Ni(ii) species (2 and 3). Compound 4 also consists of two-dimensional coordination layers in which Cu(ii) chains are interlinked by the organic spacers, but the chain has mixed mu(2)-EO-azide, mu(3)-EO-azide and mu(2)-O(carboxylate) bridges and features tetranuclear dicubane-based units sharing Cu ions or alternatively linear trinuclear units connected by long axial Cu-N/O bonds. Magnetic studies suggested that the Cu(ii) ions linked by the double azide bridges in the equatorial-equatorial fashion are strongly coupled to give a ferromagnetic S = 3/2 ground state for the trinuclear units, with very weak antiferromagnetic interactions through the equatorial-axial bridges between the units.
authors.affiliation: Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, East China Normal University, Shanghai 200062, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Ma
authors.forename: Yan-Qing
authors.initials: YQ
authors.lastname: Wen
authors.forename: Jian-Yong
authors.initials: JY
authors.lastname: Zhang
authors.forename: En-Qing
authors.initials: EQ
authors.lastname: Gao
authors.forename: Cai-Ming
authors.initials: CM
authors.lastname: Liu
mesh_terms: D001386:Azides / Q000737:chemistry*; D002264:Carboxylic Acids / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008280:Magnetics; D019216:Metals, Heavy / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*
chemical_list: C551100:1,2-bis(N-carboxymethyl-4-pyridinio)ethane; D001386:Azides; D002264:Carboxylic Acids; D019216:Metals, Heavy; D009942:Organometallic Compounds; D011725:Pyridines