Prepd by evaporating a soln of stannous oxide in hydrofluoric acid in the absence of oxygen: Gay-Lussac, Thénard, Mém. Phys. Chim. 2, 317 (1809); Nebergall et al., J. Am. Chem. Soc. 74, 1604 (1952); from tin and hydrogen fluoride: Muetterties, Inorg. Chem. 1, 342 (1962). Review: Kemmitt, Sharp, Adv. Fluorine Chem. 4, 186 (1965). Review of toxicology and human exposure: Toxicological Profile for Tin (PB2006-100006, 2005) 426 pp.