Synthesis, characterization and spectroscopic properties of some 2-substituted 1,3-indandiones and their metal complexes

Abstract

New 2-acyl-1,3-indandione derivatives, compounds 1–4, were obtained by condensation of 2-acetyl-1,3-indandione with benzaldehyde, thiophene-2-aldehyde, thiophene-3-aldehyde and furane-2-aldehyde, respectively. The structures of the newly synthesized 2-substituted 1,3-indandiones were characterized by means of spectroscopic methods (FT-IR, 1H and 13C NMR, UV-Vis and MS). Based on the obtained results it is suggested that the compounds exist in the exocyclic enolic form. Mass spectral fragmentation paths are also proposed. In order to verify the possibility for tautomerization processes of the newly synthesized compounds their absorption spectra were recorded in various solvents. Furthermore, the complexation properties of the compounds with metal(II) ions were also studied. A series of non-charged complexes with Cu(II), Cd(II), Zn(II), Co(II) and Ni(II) was isolated and analyzed by elemental analyses and IR. The paramagnetic Cu(II) complexes were studied by EPR and distorted, flattened tetrahedral structures are predicted. The other metal complexes show the presence of water molecules, most probably coordinated to the metal ion, thus forming octahedral geometry. Ultimately, the studied properties of the newly synthesized compounds, 1–4, suggest that they may find application as extracting agents for metal ions, rather than as optical sensors.