Mass spectrometry and structures of metal acetylacetonate vapours

Abstract

The mass spectra of a series of metal acetylacetonates have been rationalized in terms of ion reactions. There are many examples of a unit change in the valency of the metal atom of an ion with consequent reversal of the ion's odd- or even-electron character which influences the nature of its dissociation reactions. Occurrence or non-occurrence of change in valency correlates well with the established chemistry of the metals. Among the many reactions discussed are successive losses of two free radicals, and methyl and (with Fe(bzac)3) phenyl radical migrations. Many of the compounds give polymeric structures in the ionized vapour, and the existence of Ca3(acac)6 and possibly Ca2(acac)4 in the un-ionized vapour of the calcium complex is indicated by, inter alia, study of negative-ion mass spectra.