| Abstract: | The IR. spectra of α-thenoyl-trifluoroacetone (HTTA) and seventeen of its chelates with metal(II) and -(III) ions of the first transition series have been determined. Three series of complexes are represented: the anhydrous metal(II) species, M(TTA)2]n (M ? Ca, Mn, Co, Ni, Cu, Zn); metal(II) dihydrates, M(TTA)2(H2O)2] (M ? Mn, Fe, Co, Ni, Zn); and the metal(III) chelates, M(TTA)3] (M ? Sc, V, Cr, Mn, Fe, Ga). For each metal(II) complex, the spectra of the anhydrous and hydrated compounds are practically identical, suggesting that the anhydrous complexes have the polynuclear octahedral structure established for the corresponding acetylacetonates. Magnetic moment determinations reveal that complexes of the 3d4?3d7 ions all have spin-free configuration. Several vibrational bands with frequencies < 700 cm?1 are found to exhibit a frequency variation with d-orbital population which is consistent with the order of crystal field stabilization energies and hence with their assignment as coupled metal-oxygen stretching modes. Unique features of the spectra of Cu(TTA)2] and Mn(TTA)3] are ascribed to structural differences arising from Jahn-Teller distortion. Tentative assignments for the majority of the ligand vibrations are given. |
