Prepn: Rolsten, J. Am. Chem. Soc. 80, 2952 (1958). Review of tantalum halides: Fairbrother in Halogen Chemistry vol. 3, V. Gutmann, Ed. (Academic Press, New York, 1967) pp 123-178. Acute toxicity: K. W. Cochran et al., Arch. Ind. Hyg. Occup. Med. 1, 637 (1950).