UV solvent effect studies of some metal acetylacetonates

Abstract

Solvent effects studies of the ultraviolet absorption spectra of M(II), M(III) acetylacetonates where M - Ni(II) Mn(II), CO(II), Zn(II), Cu(II), Pd(II), Mn (III), Fe(III), Cr(III) ,and CO(III) are reported in a variety of solvents. Evidence is presented for species containing adducts of the type M(ACÀC)2.25, where ACAC is acetylacetone , S is an alcohol or water solvent molecule , and M is Ni(II) , Hn(II), CO(II) and Zn(II). Alsc monomers/polymers species are discussed. The ultraviolet spectra examination of hydrogen bonding to above metal acetylacetonates complexes has been carried out using chloroform and dichloromethane as the hydrogen-bonding agents. The data obtained indicate that Mn(III), Fe(III) Ni(II) and Hn(II) form hydrogen bonding and no hydrogen bonding occur with Co(II) , En.(II) , Cu(II) Pd(II), Cr(III) and Co(III) . It is believed that hydrogen bonding is via the chelate rings rather than the oxygen atoms. Evidence that the tetrahedral Co(II), and Zn(II) complexes change into planar form in chloroform and dichloro-dethane solution is presented. A study of solvent shifts of M(II) and M(III) acetylacetonate is reported. Larger shifts are generally recorded in polar and coordinating solvents These shifts are generally Smaller than the ones reported in the organic compound. This is undoubtedly due to the ligand field and the central field of the metal playing their part.