Copper(II) coordination polymers containing neutral trinuclear or anionic dinuclear building units based on pyrazole-3,5-dicarboxylate: Synthesis, structures and magnetic properties

Four novel copper(II) coordination polymers, namely {[Cu-3(pzcic)(2)(pYz)(H2O)(6)](H2O)}, (1), {[Cu-3(Pzdc)(2)(bPY)(H2O)(8)](H2O)(6)}(n) (2), {[Cu-4(Hpzdc)(2)(Pzdc)(2)(bPY)(2)][Cu(bpY)(H2O)(4)](n)H2O)(4)}(n) (3), and {[Cu-3(Pzdc)(2)(amPY)(H2O)(5)](H2O)(3))}(n) (4) (H(3)Pzdc = pyrazole-3,5-dicarboxylic acid, pyz = pyrazine, bpy = 4,4'-bipyridine and ampy = 2-aminopyrazine) were synthesized and characterized. Compounds 1, 2 and 4 were synthesized by layering method at room temperature while 3 was prepared under solvothermal reaction. Compounds 1 and 2 are one-dimensional (1D) chain coordination polymers, while 3 shows 1D cationic chain coordination polymer with anionic tetranuclear Cu(II) cluster. Compound 4 exhibits 1D ladder-like chain structure. Compounds 1, 2 and 4 consist of neutral trinuclear [Cu-3(pzdc)(2)] building unit which is constructed by mu(2)-pzdc(3-) bridging (5-6-5), (6-6-6), and (6-5-5) sequences of Cu(II) geometries for 1, 2 and 4, respectively. Each trinuclear unit is extended via N,N'-linkers giving polymeric chain structure. In contrast, anionic tetranuclear cluster of 3 is built up from two anionic dinuclear metallacyclic [Cu-2(Hpzdc)(pzdc)(-) building units and double mu(2)-bpy spacers. The magnetic properties of 1, 2 and 4 exhibit weak antiferromagnetic interactions among Cu(II) centers. (C) 2017 Elsevier Ltd. All rights reserved.