Electron ionization mass spectrometry of cobalt(III) β-diketonates and monothio-β-diketonates possessing aryl and fluorinated alkyl substituents

1992 ◽  
Vol 70 (3) ◽  
pp. 952-963 ◽  
Author(s):  
Mark L. J. Reimer ◽  
John B. Westmore ◽  
Manoranjan Das
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Fluorine Content ◽  
Molecular Ions ◽  
Electron Ionization ◽  
Ionization Mass ◽  
Chelate Complexes ◽  
Neutral Species ◽  
Positive Ion ◽  
Marked Dependence

Electron ionization positive ion mass spectra of 15 substituted cobalt(III) β-diketonates and monothio-β-diketonates, CoIIIL3, where L = RCXCHCOR′, R = phenyl, 2-thienyl, or 2-naphthyl; X = O or S; and R′ = CHF2, CF3, C2F5, or n-C3F7, show a marked dependence on the ligand. Molecular ions, [CoIIIL3]+•, are observed only for some of the more highly fluorinated complexes (R′ = C2F5 or n-C3F7). The [CoIIIL2]+• ion, possibly generated by ionization of CoIIL2 formed by thermal degradation, or by electron ionization of CoIIIL3, typically decomposes by elimination of a radical, i.e., L• or R′•, to yield ions containing Co(II); subsequent decompositions proceed preferentially by loss of even-electron neutral species, also to yield ions containing Co(II). Cobalt-containing ions in which fluorine has rearranged to the metal decrease in variety and abundance for the ligands with higher fluorine content. When metal-bonded oxygen is replaced by sulfur, fluorine migration to Co(III), rather than to Co(II), is preferred. These trends are consistent with a combination of several different concepts including the ability of the metal to undergo valency change, the principle of Hard and Soft Acids and Bases, and the inductive capabilities of the ligand donor atoms and of the R and R′ groups. Ion decomposition pathways are proposed. Keywords: mass spectrometry, cobalt complexes, β-diketonates, fluorinated chelate complexes.

Electron ionization mass spectrometry of aryl- and fluoroalkyl-substituted palladium(II) β-diketonates and monothio-β-diketonates

1994 ◽  
Vol 72 (5) ◽  
pp. 1302-1311 ◽  
Author(s):  
Mark L. J. Reimer ◽  
John B. Westmore ◽  
Manoranjan Das
Keyword(s):  
Mass Spectra ◽  
Electron Ionization ◽  
Electron Ionization Mass Spectrometry ◽  
Ionization Mass ◽  
Aryl Group ◽  
Mass Spectral ◽  
Transition Series ◽  
Electron Ionization Mass Spectra ◽  
Positive Ion ◽  
Sulfur Donor

Positive ion electron ionization mass spectra are presented for palladium(II) β-diketonates and monothio-β-diketonates of the general form PdII[RC(X)CHC(O)R′]2, where R = phenyl, 4-methoxyphenyl, 2-thienyl, or 2-naphthyl; R′ = trifluoromethyl, pentafluoroethyl, or n-heptafluoropropyl; and X = O or S. The mass spectral behavior is in sharp contrast to that of metals of the first transition series. The spectra of the β-diketonates are dominated by metal-containing ions that arise by migration of the R group from the ligand (L) to palladium, but there is no evidence for fluorine-to-metal transfer. These findings are consistent with HSAB theory. The strong tendency of palladium to form bonds with unsaturated carbon also leads to remarkably abundant metal-containing ions that arise by losses of CO or aryloxy radicals from [PdRL]+• ions. In contrast, in decompositions of ions in the spectra of the monothio-β-diketonates, migration of the R group is suppressed; competition for palladium dπ electrons by the sulfur donor makes palladium a poorer aryl group acceptor.

Fast Atom Bombardment Mass Spectra of Some N-α-(t-Butoxycarbonyl)-O-(diorganylphosphono)-L-serines and O-(Diorganylphosphono)seryl-Containing Dipeptides and Tripeptides

1994 ◽  
Vol 47 (2) ◽  
pp. 229 ◽  
Author(s):  
JW Perich ◽  
I Liepa ◽  
AL Chaffee ◽  
RB Johns
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectrum ◽  
High Intensity ◽  
Mass Spectra ◽  
Fast Atom Bombardment ◽  
Molecular Ions ◽  
Operating Conditions ◽  
Negative Ion ◽  
The Matrix ◽  
Positive Ion

Positive and negative ion fast atom bombardment ( f.a.b .) mass spectrometry were found to be useful methods for the analysis and structural characterization of five Nα-(t- butoxycarbonyl )-O-( diorganylphosphono )-L- serines ( organyl = Ph, Et, Me, Bzl , But), especially in the case of the sensitive benzyl and t-butyl phosphono derivatives. Under positive ion operating conditions, high intensity pseudo-molecular ions were obtained in the f.a.b . mass spectra, and the fragmentation pathway of the phenyl, ethyl and methyl derivatives was established by parent/daughter linked scanning studies to involve (a) the two-step loss of the t- butoxycarbonyl group, (b) loss of the amino acid as the neutral fragment from the [MH]+, [MH-56]+, [MH-100]+ and [MH-146]+ ions by a four- centred β-elimination rearrangement, and (c) cleavage of the phosphono phenyl and ethyl groups from only the [(RO)2P(OH)2]+ and [NH=CHCH2PO3R2+H]+ fragments. Parent/daughter linked scanning studies of the benzyl derivative showed that the prominent fragmentation involved loss of the benzyl group as the tropylium ion and that the 'apparent' [MH-90]+ peak observed in its f.a.b. mass spectrum resulted from cleavage of the phosphono benzyl group in the matrix during the bombardment process. In the case of the t-butyl derivative, parent/daughter linked scanning studies showed that the prominent fragmentation involved successive 'in-flight' loss of the phosphono t-butyl groups as isobutene. Negative ion f.a.b. mass spectrometry of the five derivatives gave f.a.b. mass spectra which displayed distinct [M-H]- anions along with high intensity [M-H-R]- and [(RO)2PO2]- fragment anions, the f.a.b . mass spectrum of the t-butyl derivative containing an additional [M-H-But-But]- fragment anion. Parent/daughter linked scanning studies established that the majority of the observed fragment anions resulted from extensive fragmentation of the Boc -Ser(PO3R2)-OH derivatives in the matrix phase followed by sputtering of the resultant fragments into the gas phase. In addition, positive ion f.a.b . mass spectrometry was found to be useful for the analysis of a series of protected O-( diorganylphosphono ) seryl-containing dipeptides and tripeptides ( organyl = Ph, Et, Me, Bzl ). The obtained spectra showed that β-elimination fragmentation of the Ser(PO3R2) residue was more pronounced with the tripeptide series and indicated that there was increased sensitivity of the O-( diorganylphosphono ) seryl residue with replacement of the Boc group by an amino acyl residue at its N-terminus.

Differentiation of 2-Alkylthioorotic Acids, Methyl and Ethyl 2-Alkylthioorotates and Hydrazides of 2-Alkylthioorotic Acids by Using Electron Ionization Mass Spectra

2008 ◽  
Vol 14 (1) ◽  
pp. 27-35 ◽  
Author(s):  
Grazyna Bartkowiak
Keyword(s):  
Molecular Mass ◽  
Mass Spectra ◽  
Chemical Species ◽  
Molecular Ions ◽  
Electron Ionization ◽  
Relative Molecular Mass ◽  
Ionization Mass ◽  
Acid Methyl ◽  
Electron Ionization Mass Spectra ◽  
Derivatives Of

Electron ionization mass spectra of 12 derivatives of 2-thioorotic acid have been discussed and general fragmentation routes of their molecular ions have been proposed. The compounds under discussion were three groups of four chemical species (2-alkylthioorotic acid, methyl 2-alkylthioorotate, ethyl 2-alkylthioorotate and 2-alkylthioorotic hydrazide) each with the same relative molecular mass. The comparison of selected ions relative abundances and their correlation with the abundance of molecular ions enable differentiation between isomeric or isobaric species in this class of compounds.

Mass spectrometry of 3,4-dihydroquinazolin-4-ones of pharmaceutical interest. Part3. Electron ionization mass spectra of 2-substituted-3-(5′-pyrazolyl)-4(3H)-quinazolinones

1992 ◽  
Vol 29 (2) ◽  
pp. 565-568 ◽  
Author(s):  
Mirella Ferrugia ◽  
Maria Luisa Bajardi ◽  
Leopoldo Ceraulo ◽  
Salvatore Plescia
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Electron Ionization ◽  
Ionization Mass ◽  
Electron Ionization Mass Spectra

Studies in organic mass spectrometry. Part15[1]. Electron ionization mass spectra of some 5-nitro-3-thiophenecarboxanilides

1992 ◽  
Vol 29 (6) ◽  
pp. 1657-1662 ◽  
Author(s):  
Leopoldo Ceraulo ◽  
Paolo De Maria ◽  
Antonella Fontana ◽  
Sara Frascari ◽  
Domenico Spinelli
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Electron Ionization ◽  
Ionization Mass ◽  
Organic Mass ◽  
Organic Mass Spectrometry ◽  
Electron Ionization Mass Spectra

ChemInform Abstract: Studies in Organic Mass Spectrometry. Part 15. Electron Ionization Mass Spectra of Some 5-Nitro-3-thiophenecarboxanilides.

ChemInform ◽  
2010 ◽  
Vol 24 (19) ◽  
pp. no-no
Author(s):  
L. CERAULO ◽  
P. DE MARIA ◽  
A. FONTANA ◽  
S. FRASCARI ◽  
D. SPINELLI
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Electron Ionization ◽  
Ionization Mass ◽  
Organic Mass ◽  
Organic Mass Spectrometry ◽  
Electron Ionization Mass Spectra
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