Mass Spectrometric Studies of Metal Acetylacetonates

The mass spectra of fifteen metal acetylacetonates measured under the electron impact with 70 eV energies are reported. The acetylacetonates can be divided into three groups, A, B, and C, according to their stability in mass spectrometeric measurements. When the electronegativity of the central metal atom is 1.5—1.6, the complexes show abundant molecular ion peaks (group A); when the electronegativity is 1.6—1.8, no molecular ion appears and the M-L cations show as the highest mass (group B); when the electronegativity is greater than 1.8, there are no peaks arising from fragments containing the metal, only acetylacetone peaks being apparent (group C). Furthermore, the mass spectra of hexafluoroacetylacetone and its copper complex were also measured.