Fast‐atom bombardment mass spectrometry of 2,4‐diketonate complexes of transition metals [V(III), Cr(III), Mn(III), Fe(III), Co(III), Ru(III) and Os(III)]

AbstractThe tris(acetylacetonate) (L3) and tris(1,1,1‐trifluoromethyl‐2,4‐pentanedionate) (L′3) complexes of transition metals V, Cr, Mn, Fe, Co, Ru and Os in their +3 oxidation states were studied under fast‐atom bombardment (FAB) conditions using 3‐nitrobenzyl alcohol as a matrix. All complexes showed the formation of molecular ion and protonated molecules [ML2]+ and [ML′2]+ are the most abundant ions in the spectra of all the metal acetylacetonates (L) and trifluoroacetylacetonates (L′) studied. Interaction of matrix with metal complexes and polynuclear metal complexes led to the formation of polynuclear species with significant abundance especially for manganese and iron complexes. Formation of these metal ions was observed with relative intensities from 3–30%. Ions corresponding to ligand‐exchange reactions were observed with moderate to high abundance in all metal complexes studied except those of ruthenium and osmium. Experiments carried out with a split FAB probe tip suggested ligand–ligand exchange reactions were not due to gas‐phase reactions but only due to solution‐phase exchanges. Osmium and ruthenium complexes do not yield polynuclear species or ions due to matrix clustering. Instead they show neutral ligand losses and formation of acetyl ion.