Di-, tetra-, and hexanuclear hydroxy-bridged copper(II) cluster compounds: Syntheses, structures, and properties

Self-assembly reactions of copper (H) ions, dicarboxylate (adipate or terephthalate) and terminal ligands (4,4'-bipyridine or phenanthroline) yielded three hydroxy-bridged Cu(II) cluster complexes: [Cu(phen)(OH)(H2O)](2)center dot(C8H4O4)center dot 8H(2)O (1), [Cu-4(bpY)(4)(OH)(4)(H2O)(2)]center dot(C8H4O4)(2)center dot 6H(2)O (2) and [Cu-6(bpy)(6)(OH)(6)(H2O)(2)]center dot(C6H8O4)(3)center dot 23H(2)o (3) (phen = phenanthroline, bpy = 2,2'-bipyridine, C8H6O4 = tereplithalic acid, C6H10O4 = adipic acid). Single crystal X-ray diffraction analyses reveal that complex 1 is a discrete dinuclear Cu2O2 motif, 2 presents a discrete chairlike tetranuclear copper(II) Cu4O4 core formed by two Cu2O2 units, and 3 assumes a discrete hexameric copper(II) Cu6O6 cluster consisting of three Cu2O2 units. The polynuclear structures are generated from the Cu(II) ions linked by the mu(2)- and/or mu(3)-OH groups. In 1-3, all Cu(II) ions show square pyramidal coordination geometry, and the dicarboxylate ions act as counteranions to keep the whole structure neutral. Thermogravimetric analyses (TGA) and magnetic properties of 1-3 were studied, respectively.