REVERSIBLE INTERCALATI0N OF GRAPHITE BY FLUORINE AND RELATED SYNTHETIC AND THERMODYNAMIC STUDIES
The pentafluorogermanate salts of a variety of cations (CI02+, NO+, SF3+' N02+, and XeF 5+) were synthesized and characterized by x-ray crystallographic and vibrational methods. The pentafluorogermanate ion was found to exist in one monomeric and at least three polymeric modifications in its salts. Lattice energy calculations and vapor pressure/temperature measurements established the following gas phase fluoride ion affinities: GeF 4 , 100(6); BF3 , 92(6); AsF 5 , 115(7); XeF 5+, 202(7); ClF2+, 223(7); SF 3+, 211(7); IF6+' 211(7) kcal mole-I. The electron affinities of the third row transition metal hexafluorides were likewise re-evaluated. + +The new graphite bifluorides, C12 HF2 and C18 HF2 were prepared; their crystal structures establish that they are correctly formulated as graphite salts. Fluorination of graphite in the presence of HF produced these salts and the first-stage hydrofluorides C~l-a(HF)a (5 > x > 2, x/a ~ 12), which were studied by XPS, n.m.r., vibrational spectroscopy, and crystallographic methods. In these compounds, fluorine forms weak,