Cu6S6 Clusters as a Building Block for the Stabilization of Coordination Polymers with NiAs, NaCl, and Related Structures: Synthesis, Structure, and Catalytic Studies

Abstract

Four new three‐dimensional heterometallic coordination polymers (CPs), [{Zn3(Hen)(OH)}{Cu6(6‐mna)6}·(H2O)6] (I), [{Zn2(OH)(en)}{Cu6(6‐mna)6}0.5·(H2O)2·EtOH] (II), [{Zn3(dap)3(H2O)}{Cu6(6‐mna)6}·(H2O)4] (III), and [{Zn2(4,4′‐bpy)0.5(OH)(H2O)}{Cu6(6‐mna)6}0.5·(H2O)] (IV) (en = ethylenediamine, 6‐H2mna = 6‐mercaptonicotinic acid, dap = 1,2‐diaminopropane, 4,4′‐bpy = 4,4′‐bipyridine), have been synthesized and their structures determined by single‐crystal X‐ray crystallography. The compounds consist of Cu6S6 octahedral clusters linked through the carboxylates to different zinc–oxo clusters. Thus, the compounds contain CuI‐ and ZnII‐based clusters, which are not commonly observed in coordination polymer structures. Compound I stabilizes in a NiAs‐related structure, compounds II and IV in a NaCl‐related structure, and compound III is a new type of network structure. All the compounds were active catalysts in the heterogeneous nitroaldol reaction.