REACTION OF DIIODINE WITH BIS-(O-DIPHENYLPHOSPHINOPHENYL) PHENYLPHOSPHINE (TP). FORMATION, CRYSTAL AND MOLECULAR STRUCTURE OF THE COMPOUND [TPO₃H]I₃-C₆H₅CH₃

Abstract

A toluene solution of the title compound (TP) and an excess of diiodine gave, surprisingly, by slow evaporation of the solvent in the air, the product [TPO₃H]I₃-C₆H₅CH₃, where one of the three phosphinic P atoms of the TP, is oxidized to POH and two to P˭O moieties, giving rise to a monocation [TPO₃H]⁺. The X-ray structure of the compound has shown that the crystals are triclinic with P1 space group, a = 11.218(5), b = 14.469(6), c = 14.626(6) Å, α = 93.67(2), β = 94.50(2), γ = 91.88(2)°, V = 2360(2) ų, Z = 2. Solution and refinement of intensity data gave final residuals of R = 0.0512. The cation shows a conformation with a ten membered ring depending on the intramolecular hydrogen bond between the two extreme oxygen atoms and on O—H(C_ph) interactions. The bond lengths P(1)—O(1), P(2)—O(2), P(3)—O(3) follow the order: 1.510(8), 1.486(7), 1.504(8) Å respectively, as expected by the existence of the hydrogen bond between H(1) and O(3). The O—P—C_phenyl bond angles fall in the 107.1(5)—114.3(5)° range. The triiodide anion is nearly linear [I(1)—I(2)—I(3) 178.2(1)°] and shows moderately asymmetric bond lengths [I(1)—I(2) 2.871(2) 1(2)—1(3) 2.969(3) Å].

Key Words:

• Diiodine
• poly-arylphosphines
• poly-arylphosphine-oxides
• X-ray
• triiodides