A structural and spectroscopic study of tris-aryl substituted R 3PI2 adducts

Article abstract of DOI:10.1016/j.poly.2011.12.023

A series of Ar₃PI₂ adducts [Ar = (o-OCH ₃C₆H₄), (m-OCH₃C₆H ₄), (p-OCH₃C₆H₄), (o-SCH ₃C₆H₄), (p-SCH₃C₆H ₄), (m-FC₆H₄), (p-FC₆H₄), (p-ClC₆H₄)] have been synthesized via the 1:1 reactions of Ar₃P with di-iodine. The ³¹P{¹H} NMR spectra of a series of Ar₃PI₂ adducts has been examined to resolve previous inconsistent reports. Ar₃PI₂ adducts do not ionize to [Ar₃PI]I in CDCl₃, and in many cases the molecular Ar₃PI₂ "spoke" adduct is stable in solution, with the degree of stability being highly dependent on the nature of the aryl group. The structures of the majority of these adducts have been established by X-ray diffraction studies. Whilst P-I and I-I bond lengths are primarily influenced by electronic effects, steric and crystal packing effects may also have an influence, as shown by the different polymorphs of (p-FC ₆H₄)₃PI₂, where a change in the conformation of the aryl groups in one of the molecules results in a lengthening of the P-I bond and shortening of the I-I bond.