Molecular architecture via coordination and multi-intermolecular interactions: Synthesis, structures and magnetic properties of one-dimensional coordination polymers of macrocyclic nickel(II) complexes with terephthalate and trans-butene dicarboxylate

Abstract

Reactions of terephthalate (TP 2−) and trans-butene dicarboxylate (BDC 2−) with macrocyclic complexes [NiL 1](ClO 4) 2, [NiL 2](ClO 4) 2, [NiL 3(ClO 4) 2 and [NiL 4](ClO 4) 2 which contain different pendant groups gave five new one-dimensional coordination polymers with the formula [NiL 1(TP)] n ( 1), [NiL 2(TP)] n ( 2), [NiL 1(BDC)] n ( 3), [NiL 3(BDC)] n ( 4) and [NiL 4(BDC)] n ( 5), respectively (L 1=3,10-bis(2-phenethyl)-1,3,5,8,10,12-hexaazacyclo-tetradecane, L 2=3,10-bis(2-benzyl)-1,3,5,8,10,12-hexaazacyclo-tetradecane, L 3=3,10-bis(2-ethyl)-1,3,5,8,10,12-hexaazacyclo-tetradecane, L 4=3,10-bis(2-hydroxyethyl)-1,3,5,8,10,12-hexaazacyclo-tetradecane). These compounds were characterized by single-crystal X-ray analyses. All structures are made up of one-dimensional chains of [NiL 1,2,3,4] 2+ units with TP 2−/BDC 2− anions. Each Ni(II) ion in the chain is six-coordinated with four nitrogen atoms from the macrocyclic ligand in the equatorial plane, and two carboxylate oxygen atoms from the TP 2− or BDC 2− group in axial position. In the structures, different intermolecular interactions and packing modes between the 1D chains are found depending on the nature of the pendant groups and the bridging ligands. The 1D chains tend to interact via π⋯π (compound 1) or CH⋯π (compounds 2 and 3) interactions when the compounds contain benzene rings as pendant groups or as bridging ligands, otherwise the 1D chains tend to interact via hydrogen bonding interactions ( 4 and 5). In 1– 4, the 1D chains are aligned in a parallel mode. In 5, the 1D chains are arranged in a crossover mode. Magnetic susceptibility measurements indicate that these compounds show weak ferromagnetic interactions between the nearest Ni(II) ions through the TP 2− or BCD 2− bridges.