Crystal Structure of 2,2,4,4-Tetrahydro-2,2,2,4,4,4-hexaphenyl-1,3,2,4-dioxadistibetane (Triphenylstibine Oxide Dimer) and Related Compounds

Article abstract of DOI:10.1021/ja00274a059

The structure of triphenylstibine oxide has long been the subject of considerable controversy in the chemical literature.Crystals, obtained by the slow cooling of a xylene solution of the crystalline form of the compound I, were subjected to a single-crystal X-ray analysis and shown to exist as a dimer with a four-membered ring containing Sb-O-Sb linkages.Molecular weight determinations and the infrared spectrum showed that this structure was unchanged in solution.The oxidation of triphenylstibine with hydrogen peroxide in acetone solution under carefully controlled conditions led to the formation of a cyclic peroxide in which a mole of acetone was incorporated into the molecule II.Its structure was determined by X-ray analysis.A compound III, previously believed to be diphenylstibinic acid anhydride, was a byproduct of this oxidation.An X-ray analysis of this material showed it to be a complex tricyclic compound with four antimony and six oxygen atoms in the rings.In addition to the crystalline form, one or more amorphous forms of triphenylstibine oxide, of unknown structure, have been prepared.The crystal data (Mo Kα, λ=0.71069 Angstroem) are as follows.I: a=10.703(5) Angstroem, b=10.521(5) Angstroem, c=14.225(8) Angstroem, space group P<*>.II: a=18.124(2) Angstroem, b=9.327(1) Angstroem, c=11.390(1) Angstroem, space group Pna2₁.III: a=11.677(5) Angstroem, b= 9.745(3) Angstroem, c=10.586(6) Angstroem, space group P<*>.