Results of electron capture and negative ion mass spectrometric studies are reported for a series of tris-chelates of the type Metal&, where L refers to the @md or enolate ion of the f3-diketone 1,1,1,5,5,5-hexafiuoro-2,4-pentaned¡one (hexafiuoroacetylacetone), and the metals are: Sc(III), Ti(III), V(III), Cr(lII), Mn(III), Fe(III), Co(III), Al(III), Ga(III), In(II1). The negative ion mass spectra were all relatively simple; the most abundant ions being the molecnlar and ligand ions for all the metals studied. Reaction schemes have been established to account for the appearance of iul significant fragment ions, many of which have been formed as a result of fluorine atom transfer processes. For the transition metal complexes, evidente for e l i a t i o n of neutral divalent metal fluorides comes from the ion decomposition reactions [Metal.L.F,]-+ [L]-, and for the Group III metal complexes, [Metal.LJ-+ [MetaLLJ as well as [Metal.LJ-+[L]-processes indicate that the metals have been reduced as a consequence of the ¡nitial electron capture and subsequent fragmentations of metal-containing ions. "he Muence of the metal atom and its 3d-electron configuration has been shown not to affect signiíicantly the electron capture processes. However, the relative instabiiities of molecular adons of the transition metal tris-complexes show an approximately linear dependence on the increasing 3d-electron populations of the metal ions from Ti(ll1) to Co(1II).