Cobalt( ii )–(dpyo)–dicarboxylate networks: unique H-bonded assembly and rare bridging mode of dpyo in one of them [dpyo = 4,4′-dipyridyl N,N′-dioxide]

Polymeric networks, {[Co(dpyo)(ox)]}(n) (1), {[Co(dpyo)(fum)(H(2)O)(2)]}(n) (1) and {[Co(dpyo)(tp)(H(2)O)(2)] x [Co(H(2)O)(6)] x (tp) x (H(2)O)}(n) (3) [ox = oxalate dianion, fum = fumarate dianion, tp = terephthalate dianion and dpyo = 4,4'-dipyridyl N,N'-dioxide] have been synthesized and characterized by single crystal X-ray diffraction analyses. The structural determination reveals 1 and 2 are covalent bonded 2D networks of 4,4 topology and of these, complex 2 undergoes a H-bonding scheme resulting in a 3D supramolecular architecture. Complex 3 is a 1D coordination polymer built up by almost collinear hexacoordinated Co(ii), doubly bridged by a tp carboxylate group and a dpyo oxygen, which in combination with lattice [Co(H(2)O)(6)](2+), tp and water molecules shows an unprecedented 3D supramolecular network through H-bonding. In the polymer the dpyo shows novel mu-4,4 bridging mode towards the cobalt ion. Low temperature magnetic interaction reveals antiferromagnetic coupling in all of the complexes.