First reported hypervalent iodine compd; utilized primarily as chlorinating reagent. Prepn from iodobenzene and chlorine gas: C. Willgerodt, Chem. Zentralbl. 56, 833 (1885); idem, J. Prakt. Chem. 33, 154 (1886) DOI; H. L. Lucas, E. R. Kennedy, Org. Synth. coll. vol. III, 482 (1955). Large scale prepn: A. Zanka et al., Org. Process Res. Dev. 2, 270 (1998) DOI. Synthetic applications: D. H. R. Barton et al., Tetrahedron 48, 8881 (1992) DOI; and new prepn methodology: X.-F. Zhao, C. Zhang, Synthesis 2007, 551 DOI. Crystal structure: E. M. Archer, T. G. D. Van Schalkwyk, Acta Crystallogr. 6, 88 (1953) DOI; J. V. Carey et al., J. Chem. Res. Synop. 1996, 358. Review: Z. Wu, Synlett 2008, 782-783 DOI.