Features of the Crystal Structure of Polynuclear Metallamacrocyclic Copper (II) Complexes Containing Polycarboxylate Anions

The addition of tartrate, oxalate and citrate anions during the one-pot synthesis of 12-MC-4 metallacrown based on β-alaninehydroximate ligands leads, respectively, to dimeric complex Cu₁₀(β-alaha)₈ (tartrate)₂·10H₂O (1) and two one-dimensional coordination polymers, Cu₅(β-alaha)₄Cu(oxalate)₂·8H₂O (2) and Cu₁₀(β-alaha)₈Cu(citrate)₂·19H₂O (3). According to X-ray diffraction data for 2 and 3, in the presence of oxalate and citrate anions, infinite chains containing alternating molecules of cationic copper (II) 12 –MC-4 metallacrown and polycarboxylate cuprate anion are formed in crystals. The distance between the metallacrown molecules in the crystal depends significantly on the choice of the initial polycarboxylate anion. In contrast to the oxalate and citrate anions, the dibasic tartrate guest anion does not lead to the formation of endless one-dimensional chains in the crystal. In this case, dimeric complex 1 is formed, for which short Cu–O contacts occur between neighboring 12-MC-4 metallamacrocycles.