Gupta Vijay, Justyniak Iwona, Chwojnowska Elżbieta, Szejko Vadim, Lewiński Janusz
Faculty of Chemistry, Warsaw University of Technology, 00-664 Warsaw, Poland.
Institute of Physical Chemistry, Polish Academy of Sciences, 01-224 Warsaw, Poland.
Inorg Chem. 2023 Oct 9;62(40):16274-16279. doi: 10.1021/acs.inorgchem.3c02177. Epub 2023 Sep 15.
Among numerous catalysts in the ring-opening copolymerization of epoxides with carbon dioxide (CO), zinc dicarboxylate complexes are the most common type, and in the family of metal-based homogeneous catalysts, zinc and magnesium complexes have attracted widespread attention. We report on the synthesis and structural characterization of a zinc-magnesium benzoate framework templated by the central hydroxide anion with μ-κ:κ:κ coordination mode, [ZnMg(μ-OH)(OCPh)] ( = 1 or 2). The resulting heterometallic system forms stable Lewis acid-base adducts with tetrahydrofuran (THF) and cyclohexene oxide (CHO), which crystallize as the hexanuclear zinc-magnesium hydroxide carboxylate cluster [ZnMg(μ-OH)(OCPh)(L)] (L = THF or CHO). Their X-ray crystal structure analysis revealed that the Zn center prefers 4-fold coordination and the Mg centers demonstrated the ability to accommodate higher coordination numbers, and as a result, the heterocyclic molecules are exclusively bonded to 6-fold Mg atoms. The heteronuclear carboxylate aggregates appeared active in the copolymerization reaction at elevated temperatures to produce an alternating poly(cyclohexene carbonate).
在环氧化物与二氧化碳（CO₂）的开环共聚反应的众多催化剂中，二羧酸锌配合物是最常见的类型，并且在金属基均相催化剂家族中，锌和镁的配合物受到了广泛关注。我们报道了一种以中心氢氧根阴离子为模板、具有μ-κ:κ:κ配位模式的苯甲酸锌镁骨架[ZnMg(μ-OH)(O₂CPh)]（n = 1或2）的合成与结构表征。所得的异金属体系与四氢呋喃（THF）和环己烯氧化物（CHO）形成稳定的路易斯酸碱加合物，它们以六核锌镁氢氧化羧酸盐簇[ZnMg(μ-OH)(O₂CPh)(L)]（L = THF或CHO）的形式结晶。它们的X射线晶体结构分析表明，锌中心倾向于4配位，而镁中心表现出能够容纳更高配位数的能力，结果，杂环分子仅与6配位的镁原子键合。在高温下，异核羧酸盐聚集体在共聚反应中表现出活性，生成交替的聚（环己烯碳酸酯）。
