TEMPERATURE-DEPENDENT ELECTRON SPIN RESONANCE STUDIES .2. CYCLOOCTATETRAENE ANION RADICAL

The cyclooctatetraene (COT) anion radical (I) has been formed by the alkali metal reduction of COT in liquid ammonia. Ion pairing affects the esr spectra of the anion radical I, influencing the line widths of the individual hyperfine splittings, the activation energy of the line-broadening process, and the spin concentration. The dependence of the hyperfine line width of the cyclooctatetraenide salts is Li+ > Na+ > K+, the reverse order of that found in ether solvents. For the COT-NH3-K system, the radical(s) observed are dependent upon the ratio of COT to its dianion (II). Equilibrium constants for the disproportionation (eq 3) in liquid ammonia have been measured. Factors affecting the direction of reaction 3 are considered.