Chlorine-containing mixed halogen adducts of triphenylphosphine, triphenylarsine, and triphenylstibine

Abstract

Conductometric titrations of PPh₃Cl₂ and AsPh₃Cl₂ with halogens and interhalogens show that the reactions are simple leading to the formation of adducts of types MPh₃Cl₂X₂(M = P or As; X₂= Br₂, I₂, ICl, or IBr) and MPh₃Cl₅I (M = P or As) in acetonitrile. The high molar conductances of the adducts suggest their formulation as MPh₃Cl⁺ClX₂^– and MPh₃Cl⁺ICl₄^– respectively. The polyhalide ions present have been identified from the u.v. spectra of the acetonitrile solutions. The reactions of MR₃(M = P, As, or Sb) with ICl and ICl₃ also give rise to highly conducting adducts in acetonitrile but the conductometric titration graphs indicate that these reactions are complex. Some of the adducts (PPh₃Cl₃I, AsPh₃Cl₃I, and AsPh₃Cl₅I) have been obtained as crystalline solids.