Dinickel(II) complexes with pyridine-substituted bis(triazolylmethyl)amine ligands: Structures and magnetic properties

Abstract

The coordination behavior of the newly prepared bis(triazolylmethyl)amine-type ligands bis[(1-R-1H-1,2,3-triazol-4-yl)methyl]amine [R = CH2Ph (L1), CH2-2-pyridyl (L2)] and 1-(1-benzyl-1H-1,2,3-triazol-4-yl)-N-((1-(pyridin-2-ylmethyl)-1H-1,2,3-triazol-4-yl)methyl)methanamine (L3) toward NiII ions was investigated. The reaction of NiCl2·6H2O with the benzyl-substituted bis(triazolylmethyl)amine ligand L1 afforded the mononuclear NiII complex Ni(L1)2Cl2 (1). On the other hand, dinuclear NiII complexes, [Ni2(L2)2Cl2]Cl2 (2) and [Ni2(L3)2Cl2]Cl2 (3), were obtained when NiCl2·6H2O was reacted with the pyridine-substituted ligands L2 and L3, respectively. Single-crystal X-ray analysis revealed that the two octahedral NiII centers in 2 and 3 are bridged by two triazole rings through nitrogen donors to generate the dinuclear complexes with a syn arrangement. Meanwhile, treatment of Ni(NO3)2 with L2 afforded the related dinickel(II) complex [Ni2(L2)2(NO3)2](NO3)2 (2′), in which two non-bridging triazole rings and two nitrate ions are positioned in an anti arrangement. Complexes 2 and 3 showed antiferromagnetic coupling between the two NiII centers (S = 1), with J values following the trend: 2′ > 2 > 3.