Metal–Metalloligand Coordination Polymer Embedding Triangular Cobalt–Oxo Clusters: Solvent- and Temperature-Induced Crystal to Crystal Transformations and Associated Magnetism

作者：Kun Fan, Feng Xu, Mohamedally Kurmoo, Xin‐Da Huang, Chwenhaw Liao, Song‐Song Bao, Fei Xue, Li‐Min Zheng · 发表于：Inorganic Chemistry · 年份：2020 · DOI：10.1021/acs.inorgchem.0c00762 · 被引用次数：20 · 研究领域：Metal-Organic Frameworks: Synthesis and Applications、Magnetism in coordination complexes、Metal complexes synthesis and properties

Reaction of the metalloligand Ir III (ppy-COOH) 3 and the anisotropic paramagnetic Co II ion under solvothermal conditions resulted in a metal–metalloligand coordination polymer, [Co II 3 (μ 3 -O)(μ-OH 2 ){Ir III (ppy-COO) 2 (ppy-COOH)} 2 (H 2 O) 4 ]·2DMF· x H 2 O ( I ). It consists of trimeric Co 3 O secondary building units (SBUs) bridged by pairs of Ir to form chains of alternate orthogonal squares. The compound undergoes two single-crystal to single-crystal transformations while retaining its general structural features. A chemical transformation occurs to give [Co II 3 (μ 3 -O){Ir III (ppy-COO) 2 (ppy-COOH)} 2 (H 2 O) 4 (DMF)]·DMF·H 2 O ( II ) by soaking in acetone, where a bridging water molecule departs and the solvent DMF bonds to the vacant site of the Co center. Both I and II undergo a temperature-induced transformation to [Co II 3 (μ 3 -O){Ir III (ppy-COO) 2 (ppy-COOH)} 2 (H 2 O) 3 (DMF)]·DMF ( III ), where one more coordinated water molecule is lost. The major difference in the three phases is in the Co coordination spheres, which have considerable consequences on the magnetism. Compound I displays paramagnetism down to 2 K, whereas II and III show weak ferromagnetism with T C values of 14 and 17 K, respectively.