Synthesis and characterization of one-dimensional nickel(II) macrocyclic complexes with bridging organic ligands

Abstract

Reactions of [Ni(L)]Cl 2·2H 2O (L=3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,0 1.18,0 7.12]docosane with 1,3,5-benzenetricarboxylate (BTC), 1,4-benzenedicarboxylate (BDC) and 2,5-pyridinedicarboxylate (PDC) in CHCl 3/water solution yield the one-dimensional nickel(II) complexes [Ni(L)] 3[BTC] 2·8H 2O ( 1), [Ni(L)(BDC)]·2H 2O ( 2) and [Ni(L)(PDC)]·H 2O ( 3). The structures were characterized by X-ray crystallography, magnetic susceptibility and thermogravimetry. Complex 1 reveals a geometrically symmetric core with a {4/6} coordination number set. The geometry around the four-coordinate Ni(3) is depicted as square planar, while the coordination geometry around the Ni(1) and Ni(2) ions is a tetragonally distorted octahedron in the direction of the chain. The crystal structures of the chain compounds 2 and 3 show an elongated octahedral trans arrangement about each nickel(II) ion. The magnetic behavior of all three compounds exhibits weak intrachain antiferromagnetic interactions with J values of −1.13 cm −1 for 1, −1.37 cm −1 for 2 and −1.47 cm −1 for 3. Compounds 1– 3 thermally decompose to form the same products. The identities of the decomposition products are discussed. The hydrogen-bonding interaction in compounds 1– 3 plays a significant role in aligning the molecules and the polymer strands in the crystalline solids.