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

Abstract

The complexes [Cu 2( o-NO 2–C 6H 4COO) 4(PNO) 2] ( 1), [Cu 2(C 6H 5COO) 4(2,2′-BPNO)] n ( 2), [Cu 2(C 6H 5COO) 4(4,4′-BPNO)] n ( 3), [Cu( p-OH–C 6H 4COO) 2(4,4′-BPNO) 2·H 2O] 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 2O] n ·4 nH 2O, in which the bridging ligand to the adjacent copper(II) ions is nicotinate N-oxide (NicoNO) the transmitted interaction is very weakly antiferromagnetic.