Synthesis, characterisation and structure determination of fluoro and non-flouro Schiff bases and their metal complexes

Schiff bases have been prepared from fluoro- and non-fluoro- substituted anilines with (a) salicaldehyde and substituted salicaldehydes and (b) acetylacetone and its trifluoro analogue. They were characterised by ultraviolet-visible, infrared, and NMR (1H, 13C, 19F) spectroscopies, and by mass spectrometry. The crystal structures of several of these Schiff bases were determined by X-ray techniques. Several cobalt(II), cobalt(III), nickel(II) and copper(II) complexes of these ligands were prepared. Crystal structures were established for four of the copper(II) complexes; bond distances in the complexes have been compared with those in the respective free ligands. Inter- and intra-molecular hydrogen-bonding is significant in many of the Schiff bases, but not in the complexes.;Anhydrous bis(acetylacetonato)cobalt(II) was obtained, and its structure established by X-ray diffraction. It was found to be square-planar. Its bond lengths, bond angles, and geometry were compared with those for other metal(II) acetylacetonates [M(II) = Cr(II), Co(II), Ni(II), Cu(II), Zn(II)], in mononuclear, polynuclear, and hydrated forms.