Novel organic ions of high-spin state. 2. Determination of the spin multiplicity of the ground state and 1H-ENDOR study of the monoanion of m-phenylenebis(phenylmethylene)

ESR and 1 H-ENDOR measurements of the title anion were performed at temperatures below 4 K. From the temperature dependence of the intensity of the ESR signal the spin multiplicity of the anion in the ground state was concluded to be quartet. The 1 H-ENDOR measurement was carried out for the randomly oriented sample by monitoring the 59- and Y-axis canonical peaks and the off-axis extra line. From the hyperfine coupling constants (hfcc) of the protons and the divalent 13 C atoms it was concluded that the excess electron in the anion occupies one of the two nonbonding π-orbitals