Mass spectral studies of metal chelates. VI. Mass spectra and appearance potentials of β-diketonates of copper(II)

The mass spectra of several copper complexes of β-diketones are discussed. The extent of fragmentation of the molecular ions depends upon the nature of the substituents on the chelate ring, being larger for electron-withdrawing, and smaller for electron-releasing substituents. In a number of fragmentations, migration of an aryl group to the copper atom occurs. Hydrogen atom migrations are also observed in some fragmentations. Attempts are made to correlate the appearance potentials of the molecular ions with acid dissociation constants of the β-diketones, formation constants and polarographic reduction potentials of the complexes, and Hammett σ constants of the substituents.