Reactions of tris(2,6-dimethoxyphenyl) arsine, tris(2,6-dimethoxyphenyl) stibine and tris(2,6-dimethoxyphenyl) bismuthine and their derivatives

Article abstract of DOI:10.1016/0022-328X(95)05716-3

Tris(2,6-dimethoxyphenyl)arsine and tris(2,6-dimethoxyphenyl)stibine (Φ₃M(Φ = 2,6-(MeO)₂C₆H₃; M = As an Sb)) reacted with common alkyl halides (RX) to give [Φ₃M-R]X, while Φ₃Bi was unreactive in benzene, or it decomposed in hot alcohols. The reactions of Φ₃M (As,Sb) with butyl bromide in acetonitrile were much faster than that of triphenylphosphine. Treatments of Φ₃M (P,As,Sb) with N-bromosuccinimide (NBS) gave [Φ₃M-OH]Br, while Φ₃Bi decomposed to give 1-bromo-2,6-dimethoxybenzene. [Φ₃M-OH]Br are soluble in water, and the acidity decreased in the order M = P > As > Sb. Treatments of Φ₃M (As,Sb) with aqueous hydrogen peroxide gave the oxides as hydrates, Φ₃MO. xH₂O (x = 1 for M = As and x = 3 for M = Sb), while Φ₃Bi was unreactive or decomposed. Φ₃PO was brominated by NBS to give Φ′₃PO.H₂O (Φ′ = 3-Br-2,6-(MeO)₂C₆H₂), which did not react with perchloric acid. In contrast, Φ₃MO.xH₂O (P,As,Sb) reacted with the acid to form the stable hydroxyonium salts [Φ₃M-OH]ClO₄. [Φ₃P-OH]ClO₄ formed crystals of stable 1 : 1 adducts with a variety of amines. [Φ₃As-OH]ClO₄ formed 1 : 1 adducts when treated with excess amounts of several amines (triethylamine,diethylamine,isobutylamine and piperidine), but they were unstable to leave amines by recrystallization. [Φ₃Sb-OH]ClO₄ formed unstable adducts with these amines, or it did not form. [Φ₃P-SH]ClO₄ formed 1 : 1 adducts with several amines, or it was deprotonated to give Φ₃PS. Φ₃MO.xH₂O (P,As) reacted with common RX (X = Br or I) to give [Φ₃M-OR]X, but Φ₃SbO.3H₂O reacted to give [Φ₃Sb-OH]X. [Φ₃P-OR]X decomposed reversibly to give Φ₃PO in solutions, although [Φ₃M-OR]ClO₄ (P,As) could be recrystallized.