Formation of acetylacetonato from complexes in acetonitrile, Fe(acac)2+, Fe(acac)2+ and Fe(acac)3, (the expression represents the solvated species: acac- is the 2, 4-pentanedionate ion), were spectrophotometrically studied. On addition of Hacac to an acetonitrile solution of Fe(ClO4)3, Fe(acac)2+ was quantitatively formed. When excess Hacac was added, only Fe(acac)2+ was obtained without forming Fe(acac)3. On the other hand, Fe(acac)2+ was quantitatively obtained by adding HClO4 to an acetonitrile solution of Fe(acac)3, and Fe(acac)2+ was also formed by adding an excess of HClO4. All the species of acetylacetonato complexes: Fe(acac)2+, Fe(acac)2+ and Fe(acac)3 were formed in the system of Fe(ClO4)3 with an addition of tetraethylammonium acetylacetonate. The resonance Raman spectra of the obtained solutions of Fe(acac)2+ and Fe(acac)2+ and of the solution of Fe(acac)3 were measured. The peaks mainly associated with v(FeO) and v(CO) are observed near 450 and 1600 cm-1, respectively. The order of v(FeO) is Fe(acac)2+ (474 cm-1) &gt
Fe(acac)2+ (462 cm-1) &gt
Fe(acac)3 (451 cm-1) and that of v(CO) is Fe(acac)2+ (1554 cm-1) &lt
Fe(acac)2+ (1578 cm-1) &lt
Fe(acac)3 (1603 cm-1). These results indicate that the coordination strength of acac- to Fe becomes weaker, because the Lewis acidity of the metal decreases as the number of coordinated acac- increases. © 1993.