Co(II)/Ni(II) coordination polymers incorporated with a bent connector: crystal structures and magnetic properties

The hydrothermal reactions of a bent ligand, 1H-3,5-bis(4-pyridyl)-1,2,4-triazole (bpt), with Co/Ni(II) ions as well as a series of polycarboxylate co-ligands yielded five new coordination polymers, namely, {[Co-2(fum)(2)(bpt)(2)(H2O)]center dot 3H(2)O}(n) (1), {[Co(mal)(bpt)(0.5)(H2O)]center dot 1.5H(2)O}(n) (2), {[Co-2(bptc)(bpt)(2)(EtOH)(H2O)(2)]center dot 2H(2)O}(n) (3), [Ni-2(btc)(bpt)(2)(H2O)(2)]center dot 6H(2)O (4), [Ni-2(Hbidc)(2)(bpt)(2)]center dot 7H(2)O (5) (here, H(2)fum = fumaric acid, H(2)mal = malonic acid, H(4)bptc = 3,3',4,4'-benzophenone-tetracarboxylate acid, H(4)btc = 1,2,4,5-benzenetetracarboxylate acid, H(3)bidc = 1H-benzimidazole-5,6-dicarboxylic acid). These complexes exhibit different architectures and magnetic behaviors: 1 has a 3D (3,5)-connected (4(2).6)(4(2).6(5).8(3)) topology, showing field-induced spin-flop transition; 2 and 3 both have a (3,4)-connected topology, exhibiting normal antiferromagnetism, with a 3D (6(3))(6(3).8(3)) symbol for 2and a 2D (6(2).8)(2)(6(4).8(2)) symbol for 3, respectively. In 4 and 5, the topological analysis results reveal that 4 can be simplified to a 3D 4-connected NbO net, while 5 is a 3D trinodal (3,4,6)-connected (6(3))(6(5).8)(6(12).8.10(2)) net. Both 4 and 5 exhibit spin-canted antiferromagnetism.