Squarato-metal(II) complexes: Part 6. Synthesis, structure and magnetic characterization of an usual squarate-based 1D copper(II) coordination polymer composed of hexanuclear entities and a trinucleating ligand scaffold

The reaction of the polynucleating ligand 1,3,5-tris[bis(2-pyridylmethyl)aminomethyl]benzene (LTDPA) with Cu(ClO4)2 · 6H2O afforded the trinuclear complex [Cu3(TTDPA)(H2O)7](ClO4)6 · 5H2O (1). When the reaction was performed in the presence of the squarate dianion, C4O42-, the compound {[Cu6(LTDPA)2(μ1,3-C4O4)3](ClO4)6 · 12H2O}n (2) was obtained. Both compounds have been characterized by X-ray crystallography, showing a trinuclear and a 1D polymeric structures for 1 and 2, respectively. Complex 2 is composed of unusual hexametallic building blocks. Magnetic susceptibility measurements (SQUID) reveal essentially uncoupled copper(II) ions in complex 1, whereas complex 2 shows weak antiferromagnetic coupling via the squarato bridges within magnetically isolated dicopper(II) subunits of the 1D chain.