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)]

The tris(acetylacetonate) (L(3)) and tris(1,1,1-trifluoromethyl-2,4-pe ntanedionate) (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 mol ecules [ML(2)](+) and [ML'(2)](+) are the most abundant ions in the sp ectra of all the metal acetylacetonates (L) and trifluoroacetylacetona tes (L') studied. Interaction of matrix with metal complexes and polyn uclear metal complexes led to the formation of polynuclear species wit h significant abundance especially for manganese and iron complexes. F ormation of these metal ions was observed with relative intensities fr om 3-30%. Ions corresponding to ligand-exchange reactions were observe d with moderate to high abundance in all metal complexes studied excep t 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, Osmiu m and ruthenium complexes do not yield polynuclear species or ions due to matrix clustering. Instead they show neutral ligand losses and for mation of acetyl ion.