An ESR investigation of the F−2 radical anion in neon matrices at 4 K

Abstract

The anion radical F−2 has been generated and trapped as a free ion in dilute neon matrices near 4 K and investigated by electron spin resonance (ESR). The magnetic parameters obtained in neon are: g∥ =2.0018(3); g⊥ =2.0185(3); A∥ =913.5(4), and A⊥ =−22.5(4) G. The neon ESR measurements are the first gas-like results and these are compared with earlier findings for F−2 in various crystalline environments. Analysis of the combined results reveal that F−2 is the most gas-like or least perturbed in the larger ionic lattices. The information obtained should be useful in estimating the degree of perturbation that typically exists for the many radicals which have been studied in ionic crystalline environments. Based upon these experimental findings for F−2 in neon matrices, an atomic value of Adip for a fluorine atom is proposed for estimating P orbital spin densities in ionic fluorine compounds. This experimental Adip for 19F is compared to commonly used theoretical values.