Charge Dispersal in the Quinuclidine Radical Cation and in the Quinuclidinium Ion, as Revealed by PE and ICR Spectroscopy

Autor: Jacques Lecoultre, Evi Honegger, E. Rolli, Cyril A. Grob, Edgar Heilbronner, Raymond Houriet
Rok vydání: 1986
Předmět:
Zdroj: Helvetica Chimica Acta. 69:2114-2126
ISSN: 1522-2675
0018-019X
Popis: The n ionization energies I and the gas-phase basicities GB of CH3-, Cl-, or CN-substituted quinuclidines have been measured by PE and ICR spectroscopy. The dependence of the shifts ΔI and ΔGB (relative to the values of the parent molecule) allow conclusions about the charge dispersal accompanying the n ionization or the protonation of quinuclidine in the gas phase. The agreement with the results of a minimal basis set abinitio calculation is excellent. Comparison of the solution pKa values with either I or GB reveals that 2-substituted quinuclidines exhibit sizeable solvent-induced proximity effects, i.e. that the corresponding quinuclidinium ions are more acidic in solution than expected on the basis of the gas-phase basicities. This agrees with earlier results concerning 2-substituted pyridines.
Databáze: OpenAIRE