Time Positron Diagnostics of Metal β-Diketonates

The effects of the nature of the metal atom and γ-substituents in aluminum(III), chromium(III), cobalt(III), and iron(III) acetylacetonates on the lifetime and intensity of a long-lived component in positron and positronium annihilation were studied by the method of positron diagnostics. An addition of a positron to the π-system of a chelate ring is supposed, which makes it possible to qualitatively estimate the basicities of the complexes. Annihilation of positrons and halogen-containing positronium β-diketonates is accompanied by the formation of a protonated complex; for γ-organylthioacetylacetonates, annihilation follows the inhibition mechanism.