Di-, Tetra-, and Hexanuclear Hydroxy-Bridged Copper(II) Cluster Compounds: Syntheses, Structures, and Properties

Self-assembly reactions of copper (II) ions, dicarboxylate (adipate or terephthalate) and terminal ligands (4,4′-bipyridine or phenanthroline) yielded three hydroxy-bridged Cu(II) cluster complexes: [Cu(phen)(OH)(H 2 O)] 2 ·(C 8 H 4 O 4 )·8H 2 O ( 1 ), [Cu 4 (bpy) 4 (OH) 4 (H 2 O) 2 ]·(C 8 H 4 O 4 ) 2 ·6H 2 O ( 2 ) and [Cu 6 (bpy) 6 (OH) 6 (H 2 O) 2 ]·(C 6 H 8 O 4 ) 3 ·23H 2 O ( 3 ) (phen = phenanthroline, bpy = 2,2′-bipyridine, C 8 H 6 O 4 = terephthalic acid, C 6 H 10 O 4 = adipic acid). Single crystal X-ray diffraction analyses reveal that complex 1 is a discrete dinuclear Cu 2 O 2 motif, 2 presents a discrete chairlike tetranuclear copper(II) Cu 4 O 4 core formed by two Cu 2 O 2 units, and 3 assumes a discrete hexameric copper(II) Cu 6 O 6 cluster consisting of three Cu 2 O 2 units. The polynuclear structures are generated from the Cu(II) ions linked by the µ 2 - and/or µ 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.