Synthesis and Crystal Structure of a One-Dimensional Coordination Polymer Containing Unusual Na₂Cu₂ Tetrametallacyclic Units

A unique coordination polymer, {[CuLNa(ClO₄)]·H₂O}_n (1), was isolated from the solution containing sodium perchlorate and the neutral macrocyclic oxamidocopper(II) complex [CuL] (H₂L = 2,3-dioxo-5,6:13, 14-dibenzo-7, 12-bis(ethoxycarbonyl)-1, 4, 8, 11-tetraazacyclotetradeca-7, 11-diene). The complex is composed of [Na₂Cu₂] tetrametallacycles bridged by perchlorate ions to form infinite one-dimensional chains which are stacked via τ-τ interactions and weak coordination bonds to result in a two-dimensional supramolecular network. The perclorate ions were found to coordinate to sodium atoms in the unusual bridging chelating tridentate mode of μ₂-(O:O′,O″).