Fragmentation and rearrangement processes in the mass spectra of perhalogenoaromatic compounds. Part X. Pentafluorophenyl dimethyl derivatives of group V

1976 ◽  
Vol 54 (9) ◽  
pp. 1478-1486 ◽  
Author(s):  
Timothy R. B. Jones ◽  
Jack M. Miller ◽  
J. Lowell Peterson ◽  
Devon W. Meek
Keyword(s):  
Mass Spectra ◽  
Energy Spectra ◽  
Group V ◽  
Fragmentation Pathways ◽  
Transfer Processes ◽  
Metastable Ions ◽  
Ion Kinetic Energy ◽  
Derivatives Of ◽  
Rearrangement Processes ◽  
Resolution Study

A comprehensive low-resolution study of the mass spectra of the compounds C6F5M(CH3)2, where M = N, P, As, is described, fragmentation pathways being assigned with the aid of normal metastable ions and mass analyzed ion kinetic energy spectra (mikes). A comparison of these spectra has re-affirmed the absence of halogen transfer processes for atoms such as N which are incapable of providing the necessary vacant orbitals apparently prerequisite in the mechanisms. The influence of increased coordination to phosphorus and effects on halogen transfer processes are discussed with respect to the mass spectra of the compounds C6F5PX(CH3)2, X = O, S, Se and the gold adducts C6F5P(CH3)2•AuX, X = Cl, Br, I.

The mass spectra of trifluoroacetyl-2,5-diketopiperazines. I. cyclo-(-Gly-X), cyclo-(-Ala-X) (X = Gly, Val, Leu, Ile), and cyclo-(-Ala-Ala)

1979 ◽  
Vol 57 (15) ◽  
pp. 2037-2051 ◽  
Author(s):  
George P. Slater ◽  
Lawrence R. Hogge
Keyword(s):  
Mass Spectrum ◽  
Mass Spectra ◽  
High Resolution Data ◽  
Fragmentation Pathways ◽  
Molecular Ion ◽  
Metastable Ions ◽  
Fragmentation Patterns ◽  
The Individual ◽  
Derivatives Of ◽  
Resolution Data

The trifluoroacetyl derivatives of the 2,5-diketopiperazines cyclo-(-Gly-X), cyclo-(-Ala-X) (X = Gly, Val, Leu, Ile), and cyclo-(-Ala-Ala) were examined by GC–MS. The molecular ion was readily detectable only for TFA-cyclo-(-Gly-Gly) (m/e 306, 9%). For those compounds containing a valyl or leucyl/isoleucyl residue the ion of highest mass in the spectrum was formed by elimination of C3H6 or C4H8, respectively, from the molecular ion. In the TFA-cyclo-(-Gly-X) series this ion corresponded to the molecular ion of TFA-cyclo-(Gly-Gly) (m/e 306), and in the TFA-cyclo-(-Ala-X) series, to the molecular ion of TFA-cyclo-(-Ala-Gly) (m/e 320). The fragmentation patterns proposed for these compounds are based on the further degradation of these parent ions so that each compound within a series has a similar mass spectrum. However, sufficient differences were detectable in the various spectra to permit identification of the individual DKP's.Many of the fragmentation pathways devised to explain the mass spectra were supported by high resolution data and appropriate metastable ions.

Fragmentation and rearrangement processes in the mass spectra of perfluoroaromatic compounds. Part XI. Heterocyclic derivatives of phosphorus and some transition metals

1979 ◽  
Vol 57 (3) ◽  
pp. 335-341 ◽  
Author(s):  
Timothy R. B. Jones ◽  
Jack M. Miller ◽  
Sylvia A. Gardner ◽  
Marvin D. Rausch
Keyword(s):  
Transition Metals ◽  
Special Interest ◽  
Mass Spectra ◽  
Central Atom ◽  
General Structure ◽  
Heterocyclic Derivatives ◽  
Derivatives Of ◽  
Rearrangement Processes

The mass spectra of a number of phospholes and metalloles of general structure 1 and 2 are[Formula: see text]discussed with respect to their fragmentation and ion rearrangement processes. Of special interest is the migration of ring fluorines to the central atom during fragmentation. The bonding principles involved for the postulated intermediates are discussed.

Fragmentation and Rearrangement Processes in the Mass Spectra of Perhalogenoaromatic Compounds. Part IX. Pentafluorophenol and Pentafluorothiophenol Derivatives of Group IV

1973 ◽  
Vol 51 (12) ◽  
pp. 1945-1951 ◽  
Author(s):  
G. F. Lanthier ◽  
J. M. Miller ◽  
A. J. Oliver
Keyword(s):  
Mass Spectra ◽  
Group Iv ◽  
Metal Fluorides ◽  
Derivatives Of ◽  
Rearrangement Processes

The mass spectra of R3MSC6F5 and R3MOC6F5 (R = CH3 or C6H5; M = Si, Ge, Sn) are reported and compared with the corresponding pentafluorophenyl derivatives. The sulfur and oxygen compounds show fewer rearrangements leading to the formation of metal fluorides than do simple C6F5 derivatives. The ions R3M+ are usually observed as the base peaks. Ions containing Sn—S appear more stable than Sn—O species, while the reverse seems true for silicon.

Mechanism and structure in chemical ionization mass spectrometry: tricyclic flavanoid compounds

1973 ◽  
Vol 26 (7) ◽  
pp. 1577 ◽  
Author(s):  
JW Clark-Lewis ◽  
CN Harwood ◽  
MJ Lacey ◽  
JS Shannon
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Chemical Ionization ◽  
Ionization Mass Spectrometry ◽  
Chemical Ionization Mass Spectrometry ◽  
Ionization Mass ◽  
Fragmentation Pathways ◽  
Fragment Ions ◽  
Metastable Ions ◽  
Fragmentation Patterns

The chemical ionization mass spectra of a series of tricyclic flavanoid compounds have been examined using isobutane and hydrogen as reagent gases and the fragmen- tation modes have been correlated systematically in terms of structure. The technique produces simple fragmentation patterns and abundant metastable ions. The use of deuterium as reagent gas reveals the influence of extraneous water on the spectra and facilitates the interpretation of the fragmentation pathways. The fragment ions appear to arise from isomeric progenitors protonated at different sites in the molecules.

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