The mass spectra of 1,1,1-trichloro-2,4-pentanedione and its Al(III), Cr(III), Fe(III), Mn(II), Co(II) and Cu(II) complexes

The compounds 1,1,1-trichloro-2,4-pentanedione, Cu(II)tca₂, Co(II)tca₂, Mn(II)tca₂, Al(III)tca₃, Cr(III)tca₃ and Fe(III)tca₃ (tca?1,1,1-trichloro-2,4-pentanedionato, [CCl₃COCHCOCH₃]^?) have been prepared and their mass spectra have been obtained. The mass spectral results have been compared with findings for comparable fluorinated and nonhalogenated compounds. Comparisons are made in terms of internal redox reactions and hard and soft acid base theory. Rearrangement of chloride from ligand to metal accompanied by the elimination of CO or other neutral even electron fragments emerges as an important reaction for the ions of these compounds. While the internal redox reactions characteristic of all previous β-diketonate complex mass spectra still occur, their importance appears reduced to some degree by the facility of the chlorine rearrangement.     

Electron-impact induced fragmentation of partially fluorinated β-diketones

The ionic fragmentation of twelve partially fluorinated β-diketones, RCOCH₂COCF₃ was studied with a medium resolution mass spectrometer. In addition to the anticipated fragmentation by β-cleavage, a number of interesting rearrangements are observed. [CF₃COCH₂CO]⁺., an ion common to all of the compounds investigated, decomposes predominantly by elimination of HF. When R is an alkyl group containing hydrogen γ to the adgacent carbonyl, the McLafferty rearrangement occurs. The [RCOCH₂CO]⁺.ion eliminates neutral RH when R is phenyl, thienyl, or cyclopropyl. An intense metastable peak, absent when R is an alkyl substituent, accompanies the rearrangement in these three compounds. A number of fragments characteristic of the R substituent are also observed in many cases. This is interpreted as indicating a considerable degree of charge localization on the R moiety.     

Mass spectral analysis of Schiff bases derived from 1,1,1-trifluoro-2,4-pentanedione and Bis(3,3′-aminopropyl)amine and bis(3,3′-aminopropyl)methylamine and their copper(II) and nickel(II) complexes

Mass spectra have been obtained for bis(5,5,5-trifluoro-4-oxopentan-2-N-propylene)amine, bis(5,5,5-trifluoro-4-oxopentan-2-N-propylene)methylamine, bis(5,5,5-trifluoro-4-oxopentan-2-N-propylene)aminocopper(II), bis(5,5,5-trifluoro-4-oxopentan-2-N-propylene)aminonickel(II), bis(5,5,5-trifluoro-4-oxopentan-2-N-propylene)methylaminocopper(II) and bis(5,5,5-trifluoro-4-oxopentan-2-N-propylene)methylaminonickel(II) using a Varian-MAT CH5 mass spectrometer. The first two compounds are seen to fragment primarily in the trimethylene chain γ to the middle nitrogen although fragmentation is seen at a variety of other sites as well. Lower molecular weight ions form a significantly larger fraction of the total ion intensity for the methylated middle nitrogen compound than for its non-methylated analog. In the metal complexes of these Schiff bases, the metal exerts its influence in two ways. The primary cleavage site inthe trimethylene bridge is β, rather than γ, to the middle nitrogen, and other fragments are produced which are ascribable to ligand to metal electron transfer.     

Mass spectra of partially fluorinated β-diketonato complexes of Al(III), Cr(III), Fe(III) and Co(III)

The mass spectra of the Al(III), Cr(III), Fe(III) and Co(III) complexes of the anions of hexafluoroacetylacetone (hfac) trifluoroacetylacetone (ttac), benzoyltrifluoroacetone (btac) and thenoyltrifluoroacetone (ttac) have been determined and are discussed here. Emphasis is placed on discerning which of the observed reactions may properly be attributed to the influence of the metal in the complex and those which may be thought of as arising from the nature of the ligand. The most important influence of the coordinated metal is related to its ability to be reduced²; however, the presence of the metal serves to prohibit or facilitate certain rearrangement reactions relative to the free protonated ligand. Since essentially all fragmentation occurs within or by loss of a ligand, the nature of the ligand determines the nature of the observed fragments. Where intramolecular com-petition of fragment types is possible (tfac, btac and ttac complexes), the most probable fragment of a given class, odd electron or even electron, is easily determined. The most commonly eliminated fragments are CF₃and CF₂. Certain metastable peaks are associated with consecutive decomposition in the field free region. Such a phenomenon appears to be common for molecules of the type studied here.