Reactivity of collisionally activated dichlorocarbene dications studied by tandem mass spectrometry.
The dissociation mechanisms of dichlorocarbene dications following collisional activation have been investigated via tandem mass spectrometric techniques and semi-empirical calculations. Three channels appear to be significant: {fx1019-1} The second channel becomes dominant at high internal energy. Production of ground state fragments (channel 1) involves a transition driven by spin-orbit coupling from the CCl 2 (2+) [Formula: see text] state to the CCl 2 (2-) ā(3)Σ u (-) state en route to the fragments. The dissociation barrier for the production of ground state fragments from the ground electronic state of CCl 2 (2+) via the spin-orbit-induced transition is equal to 420 kJ mol(-1). The dissociation pathway that corresponds to channel 3 includes a first isomerization step from the linear Cl-C-Cl(2+) structure to a bent Cl-Cl-C(2+) connectivity. The calculated isomerization barrier amounts to 550 kJ mol(-1). The calculated reverse activation barriers are compatible with the measured kinetic energy released on the fragments.
Département de Chimie Générale et de Chimie Physique, Institut de Chimie, Bātiment B6, Université de Liège, Liège 1, B. 4000, Sart-Tilman, Belgium.
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