*Article* **Metal(II) Coordination Polymers from Tetracarboxylate Linkers: Synthesis, Structures, and Catalytic Cyanosilylation of Benzaldehydes**

**Yu Li 1,†, Chumin Liang 1,†, Xunzhong Zou 1, Jinzhong Gu 2, Marina V. Kirillova 3 and Alexander M. Kirillov 3,4,\***


**Abstract:** Three 2D coordination polymers, [Cu2(μ4-dpa)(bipy)2(H2O)]n·6nH2O (**1**), [Mn2(<sup>μ</sup>6-dpa) (bipy)2]n (**2**), and [Zn2(μ4-dpa)(bipy)2(H2O)2]n·2nH2O (**3**), were prepared by a hydrothermal method using metal(II) chloride salts, 3-(2,4-dicarboxylphenoxy)phthalic acid (H4dpa) as a linker, as well as 2,2-bipyridine (bipy) as a crystallization mediator. Compounds **1**–**3** were obtained as crystalline solids and fully characterized. The structures of **1**–**3** were established by single-crystal X-ray diffraction, revealing 2D metal-organic networks of **sql**, **3,6L66**, and **hcb** topological types. Thermal stability and catalytic behavior of **1**–**3** were also studied. In particular, zinc(II) coordination polymer **3** functions as a highly active and recoverable heterogeneous catalyst in the mild cyanosilylation of benzaldehydes with trimethylsilyl cyanide to give cyanohydrin derivatives. The influence of various parameters was investigated, including a time of reaction, a loading of catalyst and its recycling, an effect of solvent type, and a substrate scope. As a result, up to 93% product yields were attained in a catalyst recoverable and reusable system when exploring 4-nitrobenzaldehyde as a model substrate. This study contributes to widening the types of multifunctional polycarboxylic acid linkers for the design of novel coordination polymers with notable applications in heterogeneous catalysis.

**Keywords:** hydrothermal synthesis; coordination polymers; crystal structures; metal-organic frameworks; carboxylate ligands; heterogeneous catalysis
