Ethylene and carbon monoxide eliminations in the ionic fragmentation of metal acetylacetonates

Abstract

ion (M = metal) in the mass spectra of Co(acac), and Co(acac), occurs through the initial loss of a methyl radical followed by sequential losses of carbon monoxide, ethylene and carbon monoxide, and yields ultimately the [MI+ ion:In this decomposition mechanism three neutral fragments of nominal m/e = 28 are postulated as being lost. Eliminations of C,H, and CO could not be distinguished using metastable data and low resolution spectra. Because of the possibility that several simultaneous processes may occur in the decomposition, we undertook a study of the [M + 28]+ and [M + 56]+ ions of the acetylacetonato complexes of Al, Cr, Fe, Co and Ni using precise mass measurements together with high resolution mass spectrometry. The important result of our study is that the processes given by (1) is not sufficient to explain the fragmentation processes. The studies were performed at 70 eV with an Hitachi Perkin-Elmer RMU-6E double-focusing mass spectrometer. The compounds were introduced into the ionization chamber at the minimal temperature required in the use of the direct inlet system.Composition assignments for the ions observed in the high resolution spectra of the indicated acetylacetonato complexes were made for the [M + 28]+ and [M + 56]+