Discrimination between hindered rotation and pair formation in phenyl-naphthalene sodium ion pairs by endor in solution

Abstract

For the radical anions of low-symmetry molecules (1-phenyl-naphthalene and 2-phenyl-naphthalene) in solution ENDOR spectra were recorded. By careful studies of the temperature dependence of the ENDOR lines different dynamic processes like hindered rotation and ion pair formation could be distinguished. The thermodynamic constants for both processes could be determined. Simple McLachlan type MO calculations were used together with approximate consideration of electrostatic repulsion to interpret the data. These model calculations are found adequate to explain the observed shifts in porton hfs couplings due to ion pairing, which are much larger for the low-symmetry phenyl-naphthalene anions than for the naphthalene anion.