Ionized ethylidene ketene and its homologue methylene ketene

1983 ◽  
Vol 61 (8) ◽  
pp. 1722-1724 ◽  
Author(s):  
Johan K. Terlouw ◽  
John L. Holmes ◽  
F. P. Lossing
Keyword(s):  
Mass Spectrum ◽  
Gas Phase ◽  
Collisional Activation ◽  
Heats Of Formation ◽  
Ionization Energies ◽  
Molecular Ion

The gas phase pyrolyses of crotonic and acrylic-trifluoroacetic anhydrides were shown to yield ethylidene ketene [CH3CH=C=C=O] and methylene ketene [CH2=C=C=O], respectively. The former was identified via the collisional activation mass spectrum of its molecular ion. The ionization energies of the two ketenes, 8.68 and 9.12 ± 0.05 eV respectively, measured using energy selected electrons, lead to 215 and 233 kcal mol−1 for their ionic heats of formation.

Sulfenic acids in the gas phase. Preparation, ionization energies and heats of formation of methane-, ethene-, and benzenesulfenic acid

1988 ◽  
Vol 53 (9) ◽  
pp. 2140-2158 ◽  
Author(s):  
František Tureček ◽  
Libor Brabec ◽  
Tomáš Vondrák ◽  
Vladimír Hanuš ◽  
Josef Hájíček ◽  
...  
Keyword(s):  
Experimental Data ◽  
Gas Phase ◽  
Radical Cations ◽  
Appearance Energy ◽  
Heats Of Formation ◽  
Ionization Energies ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis ◽  
Mndo Calculations ◽  
Sulfenic Acids

Methane-, ethene-, and ethynesulfenic acids were generated in the gas phase by flash-vacuum pyrolysis of the corresponding tert-butyl sulfoxides at 400 °C and 10-4 Pa. Benzenesulfenic acid was prepared from phenyl 3-buten-1-yl sulfoxide at 350 °C and 10-4 Pa. The sulfenic acids were characterized by mass spectrometry Threshold ionization energies (IE) were measured as IE(CH3SOH) = 9·07 ± 0·03 eV, IE(CH2=CHSOH) = 8·70 ± 0·03 eV, IE(HCCSOH) = 8·86 ± 0·04 eV, and IE(C6H5SOH) = 8·45 + 0·03 eV. Radical cations [CH3SOH].+, [CH2=CHSOH].+, and [HCCSOH].+ were generated by electron-impact-induced loss of propene from the corresponding propyl sulfoxides and their heats of formation were assessed by appearance energy measurements as 685, 824, and 927 kJ mol-1, respectively. Heats of formation of the neutral sulfenic acids and the S-(O) (C), S-(O) (Cd), S-(O) (Ct) and S-(O) (CB) group equivalents were determined. The experimental data, supported by MNDO calculations, point to sulfenate-like structures (R-S-OH) for the sulfenic acids under study.

ChemInform Abstract: Sulfenic Acids in the Gas Phase. Preparation, Ionization Energies and Heats of Formation of Methane-, Ethene-, Ethyne- and Benzenesulfenic Acid

ChemInform ◽  
1989 ◽  
Vol 20 (1) ◽  
Author(s):  
F. TURECEK ◽  
L. BRABEC ◽  
T. VONDRAK ◽  
V. HANUS ◽  
J. HAJICEK ◽  
...  
Keyword(s):  
Gas Phase ◽  
Heats Of Formation ◽  
Ionization Energies ◽  
Sulfenic Acids

Trends in the Periodic System: The Mass Spectrum of Dimethylphenyl Phosphane and a Comparison of the Gas Phase Reactivity of Dimethylphenyl Pnictogene Radical Cations C6H5E(CH3)2•+, (E = N, P, As)

2009 ◽  
Vol 15 (2) ◽  
pp. 131-144 ◽  
Author(s):  
Dirk Kirchhoff ◽  
Hans-Friedrich Grützmacher ◽  
Hansjörg Grützmacher
Keyword(s):  
Mass Spectrum ◽  
Gas Phase ◽  
Electron Impact ◽  
Radical Cation ◽  
Intensity Distribution ◽  
Phenyl Group ◽  
Radical Cations ◽  
High Energy ◽  
Molecular Ion ◽  
Distonic Ion

The mass spectrometric reactions of dimethylphenyl phosphane, 1, under electron impact have been studied by methods of tandem mass spectrometry and by using labeling with deuterium. The results are compared to those for the previously investigated dimethylaniline, 2, and dimethylphenyl arsane, 3, to examine the effects of heavy main group heteroatoms on the reactions of radical cations of the pnictogen derivatives C6H5E(CH3)2. Decomposition of the radical cation 1•+ gives rise to large peaks in the 70 eV electron impact (EI) mass spectrum for loss of a radical, •CH3, which is followed by abundant loss of a molecule, H2, and formation of ion C7H7+, and the 70 eV EI mass spectrum of the deuterated derivative 1d3 shows that excessive positional hydrogen/deuterium (H/D) exchange accompanies all fragmentation reactions. This is confirmed by the mass analyzed kinetic energy (MIKE) spectrum of the molecular ion 1d6•+ which displays a group of signals for the loss of all isotopomers, •C(H/D)3, and three signals for formation of ions C7H5D2+, C7H4D3+ and C7H3D4+. The intensity distribution within this latter group of ions corresponds to a statistical positional exchange (“scrambling”) of all six D atoms of the methyl substituents with only two H atoms of the phenyl group. In contrast, the intensity distribution of the signals for loss of •C(H/D)3 uncovers a bimodal reaction. About 39% of metastable molecular ions 1•+ eliminate •CH3 after scrambling of the six H atoms of the methyl substituents with two H atoms of the phenyl group, while the remaining 61% of metastable 1•+ lose specifically a CH3 substituent without positional H exchange. Further, the metastable ion [M – CH3]+ eliminates, almost exclusively, a molecule H2, which is preceded by excessive positional H/D exchange in the case of metastable ion [M – CD3]+. The formation of ion C7H7+ from metastable ion [M – CH3]+ is not observed and this is a minor process, even under the high energy condition of collision-induced dissociation (CID). The mechanisms of these fragmentation and exchange reactions have been modeled by theoretical calculations using the DFT functionals at the level UHBLY/6-311+G(2d,p)//UHBLYP/6-31+G(d). The key feature is a rearrangement of molecular ion 1•+ to an α-distonic isomer 1dist1•+ by a 1,2-H shift from the CH3 substituent to the P atom in competition with a direct loss of a CH3 substituent. The distonic ion 1dist1•+ performs positional H exchange between H atoms of both CH3 substituents and H atoms at the ortho-positions of the phenyl group and rearranges readily to the (conventional) isomer benzylmethyl phosphane radical cation 1bzl•+. The ion 1bzl•+ undergoes further positional H exchange before decomposition to ion C7H7+ and a radical CH3P•H or by loss of a radical •CH3. Finally, ions [M – CH3]+ of methylphenyl phosphenium structure 1a+ and benzyl phosphenium structure 1b+ interconvert easily parallel to positional H exchange involving all H atoms of the ions. Eventually, a molecule H2 is lost by a 1,1-elimination from the PH2 group of the protomer 1b–H+ of 1b+. The trends observed in the gas phase chemistry of the pnictogen radical cations dimethylaniline 2•+, dimethylphenyl phosphane 1•+ and dimethylphenyl arsane 3•+ can be comprehended by considering the variation of the energetic requirements of three competing reaction: (i) α-cleavage by loss of •H from a methyl substituent, (ii) rearrangement of the molecular ion to an α-distonic isomer by a 1,2-H shift and (iii) loss of •CH3 by cleavage of the C-heteroatom bond. 2•+ exhibits a strong N–C bond and a high activation barrier for 1,2-H shift and fragments far more predominantly by α-cleavage. Both 1•+ and 3•+ eliminate •CH3 by cleavage of the weak C-heteroatom bond. The barrier for a 1,2-H shift is also distinctly smaller than for 2•+ and, for the P-derivative 1•+, the generation of the α-distonic ion is able to compete with loss of •CH3.

Theoretical prediction of proton and electron affinities, gas phase basicities, and ionization energies of sulfinamides

2019 ◽  
Vol 31 (1) ◽  
pp. 411-421
Author(s):  
Masoumeh Ghahremani ◽  
Hamed Bahrami ◽  
Hamed Douroudgari ◽  
Morteza Vahedpour
Keyword(s):  
Theoretical Prediction ◽  
Gas Phase ◽  
Electron Affinities ◽  
Ionization Energies ◽  
Gas Phase Basicities

Synthesis and hydrolysis of gas-phase lanthanide and actinide oxide nitrate complexes: a correspondence to trivalent metal ion redox potentials and ionization energies

2015 ◽  
Vol 17 (15) ◽  
pp. 9942-9950 ◽  
Author(s):  
Ana F. Lucena ◽  
Célia Lourenço ◽  
Maria C. Michelini ◽  
Philip X. Rutkowski ◽  
José M. Carretas ◽  
...  
Keyword(s):  
Gas Phase ◽  
Metal Ion ◽  
Oxidation States ◽  
Redox Potentials ◽  
Trivalent Metal ◽  
Ionization Energies ◽  
Reduction Potentials ◽  
Hydrolysis Of ◽  
Nitrate Complexes

Gas-phase hydrolysis of lanthanide/actinide MO3(NO3)3−ions relates to the stabilities of the MIVoxidation states, which correlate with IV/III solution reduction potentials and 4th ionization energies.

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