One‐Dimensional Magnetism in New, Layered Structures: Piperazine‐Linked Copper and Nickel Oxalate Chains

Abstract

Two new coordination network materials with the composition M(pip)(ox) ( pip = piperazine; ox = oxalate; M = Ni, Cu) have been synthesised under ambient and hydrothermal conditions. These compounds adopt related structures, both consisting of intersecting [M(pip)] ϱ and [M(ox)] ϱ chains, which result in layered structures. The nickel compound crystallises in P1 . The metal ions are octahedrally coordinated and are linked by symmetric chelating bridging oxalate ions. In contrast, the copper compound crystallises in the chiral space group P2 1 2 1 2 1 . Here the copper atom displays square pyramidal coordination geometry and the oxalate ions bridge metals in an unsymmetric fashion resulting in a polar metal-oxalate chain structure. The magnetic behaviour is determined by the nature of the exchange-coupled net-

Weak ferromagnetism in cobalt oxalate crystals

“…Oxalates dihydrates containing divalent 3d transition elements, with general formula M C 2 O 4 · nH 2 O where M is a metallic ion 2+ [1][2][3][4][5][6][7][8][9][10][11], exhibit quasi-one-dimensional magnetic behavior characterized by a dominant magnetic correlation along oxalate-metal ion chains. Kurmoo [12] has reported a weak antiferromagnetic interaction in these compounds.…”

μ2-Oxalato-bridged tricopper(II) complex derived from 1,4,8,12-tetraazacyclopentadecane: Synthesis, structure and magnetic characterization

“…1 ranging from the very common bis-bidentate bonding mode in I to the bidentate-monodentate bonding to one of the terminal oxygens in II and III or to coordinated oxygen in IV. These multiple binding mode of structures II, III and IV may lead to the formation of polynuclear complexes of interesting magnetic coupling and of different nuclearity and dimensionality [8,[16][17][18][23][24][25][26][27]. The present study was undertaken to investigate the structural and magnetic properties of a novel oxalato-tricopper(II) complex based on 1,4,8,12-tetraazacyclopentadecane (tacp),…”

“…Many oxalato-nickel(II) and -copper(II) compounds have been isolated, and magnetically and structurally characterized [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. In most cases, dinuclear metal(II) complexes were obtained where the oxalate ligand is binding the two metals in bis-bidentate bridging mode [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16].…”

[Ni(bpy)(ox)]: a candidate in the class of Haldane gap systems (bpy = 2,2ʹ-bipyridine, ox = oxalate)

“…In addition, oxalate is an efficient mediator of magnetic exchange interactions [1,3,9,10]. Exploring the rigid symmetric bis-chelate coordination mode of ox resulted in many one-dimensional (1-D) complexes based on Ni(II) [5,[10][11][12][13][14][15][16], which were shown to be representative of Haldane gap or spin glass behavior [17][18][19].…”