Prepn and crystal structure: V. Russell et al., Acta Crystallogr. 6, 870 (1953); M. E. Jones, R. E. Marsh, J. Am. Chem. Soc. 76, 1434 (1954). Use as reagent in metathesis reactions: E. G. Gillan, R. B. Kaner, Chem. Mater. 8, 333 (1996). Superconductive properties: J. Nagamatsu et al., Nature 410, 63 (2001). Brief review: R. J. Cava, ibid. 23-24.