Thermochernistry of organic and heteroorganic species. Part XIII. Structural aspects and thermochemical approach to isomerization and fragmentation of negative ions. Simple bond cleavage and hydrogen rearrangement processes

摘要

Many hundreds of isomerization and fragmentation processes for negatively charged ions obtained in electron attachment dissociation, collision induced dissociation and negative chemical ionization have been analyzed to find out certain regularities in gas-phase monomolecular chemistry of negative ions like it was earlier performed for positive ions [Eur. J. Mass Spectrom., 8 (2002) 409]. This analysis combined with systematic application of the data on energies of the processes (appearance energies, isolation of stable resonance states on energetical scale in the range 0-15 eV, enthalpies of formation of even negative ions and electron affinities of corresponding free radicals) allowed to come to quite definite conclusion of validity of Eyring's quasi-equilibrium theory (QET) to mass spectrometry of negative ions. However, it is valid only in the limits of a stable resonance state rather than in a whole range of energies being applied. The validity of QET was illustrated by many diverse simple bond cleavage and rearrangement processes.