Roles of Anions in Pyridinecarboxamide-copper(II) Supramolecular Networks

Three complexes Cu(ppca)2(H2O)2(NO3)2 (1), Cu2(μ-OH)2(ppca)2(H2O)4}·(ClO4)2 (2) and Cu2(μ-CH3COO)4(ppca)2 (3) have been synthesized by the reaction of copper(II) salts with N-phenyl-4-pyridinecarboxamide (ppca) and characterized. For anions, in complex 1, NO3- coordinated with copper(II), in complex 2 perchlorate anion did not take part in coordination, the copper(II) cations were connected by μ-OH to form a dinuclear unit, and complex 3 had a dimeric copper(II) carboxylate paddle-wheel core. Noncovalent interactions linked these complexes to form supramolecular networks. Different coordinating modes of anions controlled modes of intermolecular interactions, which resulted in different final structures.