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

lThe complexes [Cu(2)(o-NO(2)-C(6)H(4)COO)(4)(PNO)(2)] (1), [Cu2(C6H5COO) 4(2,20-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)center dot H2O](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 {Cu2}(4+) paddle wheel units and no discernible interactions between the units. The complex 5, [Cu(NicoNO)(2)center dot 2H(2)O](n)center dot 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. (C) 2010 Elsevier B. V. All rights reserved.