Measurements of equilibria and reactivity of cluster ions at atmospheric pressure: reactions of Cl-(CHCl3)0-2 with methyl bromide and methyl iodide

Abstract

Measurements by the kinetic ion mobility mass spectrometer (KIMMS) of (i) equilibrium constants for the clustering reactions X-(CHC13)i-l + CHC13 + X-(CHC13)i9 where X-= C1-and Br-and i = 1 or 2, (ii) single ion mobilities for the ions Cl-(CHC1&2 and Br-(CHCl3)0-1, and (iii) rate constants for the s N 2 nucleophilic displacement reactions of a distribution of chloride cluster ions, CI-(CHC13)&2, with CH3Br and with CH31 in nitrogen buffer gas a t atmospheric pressure are reported. A unique feature of the present equilibrium and kinetic measurements is that they are obtained from ion mobility measurements and, therefore, are not subject to potential sources of error that can accompany mass spectrometric-based measurements involving aperture sampling of a high-pressure ion source. Another unique feature of the present investigation is that the reactivity of a selected set of cluster ions is determined under physical conditions in which the individual ions are kinetically labile with respect to cluster decomposition and growth.

Thermochemistry and structures of solvated SN2 complexes and transition states in the gas phase: experiment and theory

“…7 all data for Eqs. (17)- (19) from Tables 10-12 are shown together as schematic potential energy profiles. With the exception of PH 3 the transition states [(S)ClCH 3 Cl] − ‡ can all be seen to be lower in H • 298 value than the separated individual reactants, Cl − + CH 3 Cl + S. This means that it could be possible to kinetically excite 35 Cl − (S), for instance, and to monitor formation of 37 Cl − and/or 37 Cl − (S) from these energetic collisions with CH 3 Cl (Eq.…”

“…(3)) using a variety of experimental techniques [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. By performing these kinds of experiments it is hoped to gain additional insight into the intrinsic contribution of the solvent molecules to the progress [25] of these reactions.…”

“…For most mono-solvated reactions only a small fraction of the leaving groups are solvated (Eq. (4)) [11][12][13][14][15][16][19][20][21][22]24,25], even though this reaction pathway is more exothermic than formation of the non-solvated leaving group (Eq. (5)).…”

A determination of the effective temperatures for the dissociation of the proton bound dimer of dimethyl methylphosphonate in a planar differential mobility spectrometer

“…Ions in fields below 10 Td have T eff essentially equal to T, the temperature of the surrounding gas. The reactions of ions in ion mobility spectrometers under low field conditions at atmospheric pressure and well-defined temperatures can therefore provide kinetic and thermodynamic data [8][9][10][11][12][13][14][15].…”

The effect of ion molecule reactions on peaks in ion mobility spectrometry

“…In addition, temperature has profound effects on all processes happening in the drift region such as collision, diffusion, thermodynamics, and kinetics of ion molecule reactions. Study of ion-molecule reactions by IMS has been the subject of a number of works [6][7][8][9][10][11][12][13][14][15][16]. The aim of this work is to closely investigate the effects of ion molecule reactions in the drift region of IMS on the peak shape, peak displacement, and the resolution.…”