Mercury(II) halide adducts of transition-metal complexes. Part II. Tertiary-phosphine and -arsine complexes of rhodium(III) and iridium(III)

Abstract

Treatment of mercury(II) halides with complexes [MX₃(L)₃](both isomers) or [IrX_{3 –n}(H)_nL₃](M = Rh or Ir; X = Cl, Br, or I; 1 ⩽n⩽ 3) gives adducts of the types [MX₃(L)₃(HgY₂)](I: M = Rh, X = Y = Cl, L = AsMe₂Ph or PMe₂Ph; M = Ir, X = Y = Cl, L = PEt₃, PPrⁿ₃, Buⁿ₃, PMe₂Ph, AsEt₃, AsMe₂Ph, or AsEt₂Ph; M = Ir, X = Y = Br, L = PMe₂Ph or AsMe₂Ph; M = Ir, X = Cl, Y = Br or I, L = PEt₃), (II: M = Ir, X = Cl, Y = Cl or Br, L = PEt₃), or (III: M = Ir, X = Br, Y = Cl, L = PEt₃), and [MH(X)₂(L)₃(HgY₂)](IV: M = Ir, X = Y = Cl, L = PMe₂Ph or PEt₂Ph; X = Y = I, L = PMe₂Ph; X = Y = Br, L = PEt₂Ph), respectively, believed to have a double halide bridge between the metal atoms, often easily dissociated. Hydride ligands in certain stereochemistries in the precursors can act as reductants towards mercury(II) halides. A bis-HgCl₂ adduct [IrCl₃(PEt₃)₃(HgCl₂)₂], (V), is also reported. SnCl₂Reacts with the adduct [IrCl₃(PEt₃)₃(HgCl₂)] to give [IrCl₂(SnCl₃)(PEt₃)₃], (XI); the reaction is reversed by the action of HgCl₂. The configuration of the complexes and their reactivity have been studied mainly using i.r. (4 000–200 cm^–1) and ¹H(methyl) n.m.r. spectroscopies.