Aromatic N-oxide bridged copper(II) coordination polymers: Synthesis, characterization and magnetic properties

The complexes [Cu(2)(o-NO(2)–C(6)H(4)COO)(4)(PNO)(2)] (1), [Cu(2)(C(6)H(5)COO)(4)(2,2′-BPNO)](n) (2), [Cu(2)(C(6)H(5)COO)(4)(4,4′-BPNO)](n) (3), [Cu(p-OH–C(6)H(4)COO)(2)(4,4′-BPNO)(2)·H(2)O](n) (4), (where PNO = pyridine N-oxide, 2,2′-BPNO = 2,2′-bipyridyl-N,N′-dioxide, 4,4′-BPNO = 4,4′-bipyridyl-N,N′-dioxide) are prepared and characterized and their magnetic properties are studied as a function of temperature. Complex 1 is a discrete dinuclear complex while complexes 2–4 are polymeric of which 2 and 3 have paddle wheel repeating units. Magnetic susceptibility measurements from polycrystalline samples of 1–4 revealed strong antiferromagnetic interactions within the {Cu(2)}(4+) paddle wheel units and no discernible interactions between the units. The complex 5, [Cu(NicoNO)(2)·2H(2)O](n)·4nH(2)O, in which the bridging ligand to the adjacent copper(II) ions is nicotinate N-oxide (NicoNO) the transmitted interaction is very weakly antiferromagnetic.