Prepd by passing fluorine through liq IF5 at 90°, then heating the vapors to 270°: Ruff, Keim, Z. Anorg. Allg. Chem. 193, 176 (1930); Kwasnik in Handbook of Preparative Inorganic Chemistry vol. 1, G. Brauer, Ed. (Academic Press, New York, 2nd ed., 1963) pp 160-161. May also be prepd from fluorine and dried PdI2 or KI to minimize formation of the impurity, IOF5: Bartlett, Levchuk, Proc. Chem. Soc. London 1963, 342; Selig et al., J. Phys. Chem. 71, 2739 (1967). Reviews: Kemmitt, Sharp, Adv. Fluorine Chem. 4, 246-247 (1965); Stein, “Physical and Chemical Properties of Halogen Fluorides” in Halogen Chemistry Vol. 1, V. Gutmann, Ed. (Academic Press, New York, 1967) pp 133-224; Meinert, Z. Chem. 7, 41-57 (1967).