Spectra–structure relationship: Synthesis, characterization of copper(II) complexes with ibuprofenate, o-methoxybenzoate, p-ethoxybenzoate and single crystal X-ray structure determination of [ trans-Cu(en) 2(H 2O) 2](L) 2 where en = ethylenediammine, L = o-methoxybenzoate/ p-ethoxybenzoate

Abstract

To investigate the spectra–structure relationship, three new copper(II) complex salts of composition [ trans-Cu(en) 2(H 2O) 2](L 1) 2 2H 2O (1), [ trans-Cu(en) 2(H 2O) 2](L 2) 2 (2) and [ trans-Cu(en) 2(H 2O) 2](L 3) 2 (3) (where L 1 = ibuprofenate, L 2 = o-methoxybenzoate and L 3 = p-ethoxybenzoate) were obtained when ethylenediamine was added to ‘Cu(L) 2’ (L = L 1/L 2/L 3) in methanol–water solution. The intermediate ‘Cu(L) 2’ salts were prepared by reaction of copper sulphate with sodium salt of ibuprofen, o-methoxybenzoic acid or p-ethoxybenzoic acid, respectively, in aqueous medium in 1:2 molar ratio. The newly synthesized complex salts have been characterized by elemental analyses, spectroscopic techniques (UV/visible and IR), magnetic moment determinations and conductance measurements. X-ray structure determination revealed an ionic structure consisting of one [ trans-Cu(en) 2(H 2O) 2] 2+, two [C 8H 7O 3] - ions in 2 and one [ trans-Cu(en) 2(H 2O) 2] 2+, two (C 9H 8O 3) - ions in 3. In these complex salts central metal ion copper(II) is coordinated by four nitrogen atoms, originating from two chelating ethylenediamine ligands and two oxygen atoms of two coordinated water molecules, showing distorted octahedral geometry around copper metal ion. Both of these structurally correlated octahedral [ trans-Co(en) 2(H 2O) 2] 2+ species have shown absorption at λ max ≈ 540 nm in the UV/visible spectrum.