The formation of (CH3)7Si2+ in (CH3)4Si/CH4 mixtures and CH3− exchange reactions between (CH3)4Si, (CH3)4Ge, and (CH3)4Sn studied by high pressure mass spectrometry

1987 ◽  
Vol 65 (12) ◽  
pp. 2849-2854 ◽  
Author(s):  
Anastasia C. M. Wojtyniak ◽  
Xiaoping Li ◽  
John A. Stone
Keyword(s):  
Mass Spectrometry ◽  
High Pressure ◽  
Equilibrium Constant ◽  
Mass Spectrometer ◽  
Excellent Agreement ◽  
Ion Source ◽  
Methyl Groups ◽  
Exchange Reactions ◽  
Equilibrium Reactions ◽  
Association Equilibrium

The association equilibrium [Formula: see text] has been studied in a high pressure mass spectrometer ion source using tetramethylsilane/methane mixtures. Measurement of the equilibrium constant over a range of temperatures yields ΔH0 = −22.3 ± 0.4 kcal mol−1 and ΔS0 = −35.2 ± 0.9 cal mol−1 K−1. Collision-assisted dissociation experiments suggest that the methyl groups retain their integrity in (CH3)7Si2+. Mixed ions such as (CH3)7SiGe+ and (CH3)7GeSn+ were not observed in mixtures of (CH3)4X and (CH3)4Y(X ≠ Y = Si, Ge, Sn). Instead CH3− transfer equilibrium reactions were observed viz. [Formula: see text] (ΔH0 = −10.2 ± 1.2 kcal mol−1, ΔS0 = −3.7 ± 2.4 cal K−1 mol−1) and [Formula: see text], ΔS0 = −0.9 ± 1.6 cal K−1 mol−1. These are in excellent agreement with some published differences in appearance potentials for (CH3)3X+ from (CH3)4X (X = Si, Ge, Sn).

The gas phase reactivity of the dimethylchloronium ion with alkylbenzenes

1981 ◽  
Vol 59 (15) ◽  
pp. 2412-2416 ◽  
Author(s):  
John A. Stone ◽  
Margaret S. Lin ◽  
Jeffrey Varah
Keyword(s):  
High Pressure ◽  
Gas Phase ◽  
Mass Spectrometer ◽  
Aromatic Hydrocarbons ◽  
Relative Rate ◽  
Ion Source ◽  
Nucleophilic Displacement ◽  
Rate Of Reaction ◽  
Displacement Reactions ◽  
Bonded Complexes

The reactivity of the dimethylchloronium ion with a series of aromatic hydrocarbons has been studied in a high pressure mass spectrometer ion source using the technique of reactant ion monitoring. Benzene is unreactive but all others, from toluene to mesitylene, react by CH3+ transfer to yield σ-bonded complexes. The relative rate of reaction increases with increasing exothermicity in line with current theories of nucleophilic displacement reactions.

Hypervalent Molecular Cluster: C28H4

2005 ◽  
Vol 494 ◽  
pp. 181-186
Author(s):  
M. Veljković ◽  
O. Nešković ◽  
A. Djerić ◽  
S. Veličković ◽  
V. Šipka
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectrometer ◽  
Source Parameters ◽  
Carbon Cluster ◽  
Ion Source ◽  
Molecular Cluster ◽  
Hydrogen Atoms ◽  
Cluster Source ◽  
The Impact

A growing number of recent publications on clusters reflect a tremendous interest in these particles. These studies reveal new fundamental physical and chemical aspects of matter. Clusters are called the fifth state of matter: liquid, solid, cluster, gas and plasma. In this work, a carbon cluster was generated by a spark cluster source and detected by single focusing mass spectrometer in situ. We examined the effects of cluster source parameters on the generation of carbon cluster and report our initial results. This method should be useful for studying the mechanism of fullerene formation. In the case when carbon clusters generated in plasma arc are carried by the Ar or H2 gas flow downstream through a vacuum chamber to the ion source of mass spectrometer, we obtained a small binary carbon cluster C28H4 (hydrogenated fullerene). The empty fullerene is tetravalent and strongly binds four hydrogen atoms, which significantly weakens two different sets of bonds and leads to an open-shell electronic structure. Conclusion is that endohedral C28H4 are hypervalent. We have demonstrated how in situ mass spectrometry has led to the rapid development of an important branch of synthetic fullerene chemistry that has yielded many new small fullerenes and related derivatives with novel structures and properties. The impact of mass spectrometry on the synthesis of fullerene derivatives is the subject of this paper. Significantly, a large fraction of products could be condensed on a specially designed collection plate, which allows further spectroscopic characterization of new derivatives.

High mass resolution glow discharge mass spectrometry using an external ion source FT-ICR mass spectrometer

1993 ◽  
Vol 65 (20) ◽  
pp. 2801-2804 ◽  
Author(s):  
Clifford H. Watson ◽  
John. Wronka ◽  
Frank H. Laukien ◽  
Christopher M. Barshick ◽  
John R. Eyler
Keyword(s):  
Mass Spectrometry ◽  
Glow Discharge ◽  
Mass Spectrometer ◽  
Ion Source ◽  
Mass Resolution ◽  
Glow Discharge Mass Spectrometry ◽  
High Mass ◽  
High Mass Resolution ◽  
Ft Icr

Ion mobility spectrometry-mass spectrometry examination of the structures, stabilities, and extents of hydration of dimethylamine–sulfuric acid clusters

2016 ◽  
Vol 18 (33) ◽  
pp. 22962-22972 ◽  
Author(s):  
Jikku M. Thomas ◽  
Siqin He ◽  
Carlos Larriba-Andaluz ◽  
Joseph W. DePalma ◽  
Murray V. Johnston ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Sulfuric Acid ◽  
Mass Spectrometer ◽  
Ion Mobility Spectrometry ◽  
Ion Mobility ◽  
Atmospheric Pressure ◽  
P Uptake ◽  
Ion Source ◽  
Cluster Ions ◽  
Water Molecules

Uptake of water molecules by dimethylamine–sulfuric acid cluster ions mitigates dissociation in atmospheric pressure ion source mass spectrometer inlets.

Concluding remarks

1979 ◽  
Vol 293 (1400) ◽  
pp. 167-168
Keyword(s):  
Mass Spectrometry ◽  
High Pressure ◽  
Mass Spectrometer ◽  
Organic Molecules ◽  
Negative Ions ◽  
Negative Ion ◽  
Current Status ◽  
Source Analysis ◽  
Biological Chemistry ◽  
Mass Spectrometers

It is good that from time to time, a group of leading workers in a field should come together to discuss the current status of their research, and the direction in which it will most probably develop. We should all be grateful to the Royal Society in acting as hosts to this conference and to Professor Johnson and Professor Beynon for organizing it. I think that all will agree that the high quality of the papers presented have made this occasion a very memorable and valuable one. I should also like to thank the organizers for the relaxed atmosphere of the Conference, which made it so enjoyable. The last decade has seen a tremendous growth in both the instrumentation and techniques of mass spectrometry and the applications of mass spectrometry to organic and biological chemistry. On the instrumentation side, the modification of a double focusing mass spectrometer to yield ion kinetic energy spectra, giving information about the progenitors of a given ion, and the reversed geometry instrument, yielding information as to the daughter ions of a given parent, have both considerably contributed to our knowledge of the fragmentation of organic molecules. Again the development of special sources, field ionization and field desorption, the linking of a gas or high pressure liquid chromatograph to a mass spectrometer, and the introduction of high pressure sources for chemical ionization, have all made important contributions to organic and biological chemistry. The study of negative ions has also shed considerable light on the structure of organic molecules. Finally, the linking of computers with mass spectrometers has enabled results to be obtained very much more rapidly than in the past, and also made possible library searches to identify the substances present. Mr Craig discussed recent modifications in the source, analysis systems and detector systems of commercial mass spectrometers. Of particular importance was the increased sensitivity obtained by more effective ion collection. Among the newer techniques described during the meeting were g.c.-m.s. (Professor Jellum, Professor Jackson, Dr Morris, Professor Brooks and Professor Eglinton), collisional activation (Professor McLafferty and Dr Morris), negative ion mass spectrometry (Professor Jennings) and reversed geometry mass spectrometry (Professor Beynon).

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