Solvothermal Subcomponent Self-Assembly of Cubic Metal–Imidazolate Cages and Their Coordination Polymers

Abstract

A series of Ni–imidazolate cubic cages, one-dimensional and two-dimensional coordination polymers based on the cubic cages, have been prepared by solvothermal <i>subcomponent self-assembly</i> of 5-methyl-4-formylimidazole, <i>m</i>-xylylenediamine, and Ni^II salts with varied anions. These compounds have been characterized by single-crystal X-ray diffractions, elemental analysis, IR spectra, and powder X-ray diffractions. The formation of an oligomerized coordination cage or an infinite coordination polymer depends on the anions chosen. An oligomerized 8-nuclear Ni–imidazolate cubic cage is formed when the anion Cl^–, Br^–, I^–, SCN^–, NO₂^–, or NO₃^– is utilized in the reactions, and a two-dimensional coordination polymer based on the Ni–imidazolate cubic cage will be obtained when N₃^–, (CN)₂N^–, or (CN)₃C^– act as the anions. When only ClO₄^– or both ClO₄^– and [Ni­(C₄N₂S₂)₂]^2– (C₄N₂S₂ = dimercaptomaleonitrile) as anions exist in the reaction mixture, a ladder-like one-dimensional coordination polymer based on the Ni–imidazolate cubic cage and formate is formed unpredictably