Kinetic-energy dependence of competitive spin-allowed and spin-forbidden reactions: V++CS2

Abstract

The kinetic-energy dependence of the V++CS2 reaction is examined using guided ion-beam mass spectrometry. Several different ion sources are used to systematically vary the V+ electronic state distributions and elucidate the reactivities of both the ground and excited state V+ cation. The cross section for VS+ formation from ground state V+(5D) exhibits two endothermic features corresponding to the formation of ground state VS+(3Σ−) and excited state VS+(5Π). The thresholds for these two processes are in good agreement with theoretically determined excitation energies. The cross section for spin-forbidden formation of ground state VS+(3Σ−) exhibits an unusual variation with kinetic energy that is attributed to the energy dependence of the surface-crossing probability. From the thresholds associated with the formation of VS+ and V(CS)+, D0(V+–S)=3.72±0.09 eV and D0(V+–CS)=1.70±0.08 eV are derived. Further, circumstantial evidence for formation of a high-energy isomer of V(CS)+ is obtained.

Mass spectrometry—Not just a structural tool: The use of guided ion beam tandem mass spectrometry to determine thermochemistry

“…In such cases, an additional E Ϫ1/2 factor needs to be introduced such that m is effectively 1.5. As discussed in detail in our most recent work [29], this expression can be justified by appealing to a Landau-Zener model [31,32] and agrees with several modern theoretical treatments [33,34] for the kinetic energy dependence of the crossing probability between diabatic surfaces of different spin multiplicities.…”

“…However, we [28,29] and others [30] have documented exceptions to this conclusion associated with reactions that are limited by coupling between reaction surfaces of different spin. In such cases, an additional E Ϫ1/2 factor needs to be introduced such that m is effectively 1.5.…”

How a Quantum Chemical Topology Analysis Enables Prediction of Electron Density Transfers in Chemical Reactions. The Degenerated Cope Rearrangement of Semibullvalene

“…61 On the other hand, from a fundamental point of view, the chemical reactivity of transition metal oxides is strongly influenced by the availability of multiple low-lying electronic states in these species. 31,62,63 This means that the reactions involve several electronic states that may also have different spins, namely, it should involve spinconserving and spin-inversion processes.…”

Thermodynamic and kinetic properties of scandium (I) ion reacting with SCO in gas phase

“…There are a number of reaction types such as coordination, insertion, etc., which have been studied both experimentally and theoretically [5]. Studies by Jiang and Rue et al [1,6] have calculated for the reactions of V + (Fe + ) and CS 2 , and found that they proceed via an insertion-elimination mechanism. As for the reactions of a transition metal ion with SCO, this was observed to be more complicated as a consequence of the molecule having both a C-S bond and a C-O bond.…”