Variation in the coordination mode of arenedisulfonates to copper(II): synthesis and structural characterization of six copper(II) arenedisulfonate complexes

Abstract

Six copper(II) arenedisulfonate complexes with the general formula Cu(N₄)(nds/bpds)·nH₂O (nds = naphthalenedisulfonate, bpds = biphenyldisulfonate) have been synthesized in aqueous solution and structurally characterized by X-ray single crystal diffraction, IR and UV spectroscopies, TGA and DSC. In Cu(en)₂(1,5nds)·2H₂O 1, Cu(N-meen)₂(2,6nds)·2H₂O 2 (N-meen = N-methylethylenediamine), Cu(dpn)₂(bpds) 3 (dpn = 2,3-diaminopropane), and Cu(cylam)(1,5nds) 4 the SO₃⁻ group coordinates monodentately to the axial position of Cu²⁺ which is equatorially coordinated by four amino nitrogens. In 1 and 4 intramolecular hydrogen bonds are formed between the SO₃⁻ oxygens and amino hydrogens which reinforce interaction between the SO₃⁻ group and Cu²⁺ complex cation. In Cu(dpn)₂(1,5nds)·2H₂O 5 and Cu(N,N′-meen)₂(1,5nds)·3H₂O 6 (N,N′-meen = N,N′-dimethylethylenediamine), due to the steric hindrance caused by the methyl substitution of the amino ligands and the rigidity of the naphthalene ring, water molecules, instead of the bulky SO₃⁻ group, coordinate to the axial position of Cu²⁺. Structures 1–4 represent the first synthesis and structural characterization of polymeric 1-dimensional structures constructed by arenedisulfonates and divalent transition metals. Also, 1 crystallizes in the enantiomorphic space group P4₁2₁2 and displays interesting chiral grids constructed by ionic hydrogen bonds. The coordination geometries of Cu²⁺, as well as the coordination modes of arenedisulfonates, are discussed in detail.