Reactions of bis(triphenylphosphonio)isophosphindolide salts with mercury(II) compounds: Coordination induced addition and oxidation reactions and synthesis of a monomeric 1:1 complex of the type [R(2)(R'O)P]HgBr2

Bis(triphenylphosphonio)isophosphindolide triflate (1[CF3SO3]) reacted with HgCl2 and H2O or MeOH to give a phosphinito complex which was converted with excess HgCl2 into the dimercury complex 5. In contrast, methanolysis of 1[X] (X = CF3SO3, Br) in the presence of Hg(OAc)(2) afforded the phosphonium cation 9. A mercury complex 8 was isolated for X = Br as a reaction intermediate. Salts of a macrocyclic cation with a constitution similar to that of 9 were obtained by reaction of 1[CF3SO3] with Hg(OAc)(2) and triethylene glycol. The products were characterised by H-1, C-13, and (31)p NMR spectroscopy; in addition, Hg-199 NMR data of some complexes were obtained from 2D (31)p, Hg-199 Shift correlations. Complexes 5 (space group P2(1)2(1)2(1), Z = 4, a = 12.449(2) Angstrom, b = 17.583(3) Angstrom, c = 23.111(3) Angstrom, V = 5058.8(14) Angstrom(3), 8917 reflections refined to R(w2) = 0.103) and 8 (space group C2/c, Z = 8, a = 20.028(2) Angstrom, b = 15.513(2) Angstrom, c = 30.247(8) Angstrom, beta = 91.91(1)degrees, V = 9392(3) Angstrom(3), 7955 reflections refined to R(w2) = 0.177) were further characterized by single crystal X-ray diffractommetry. Compound 8 is the first example of a monomeric complex of the type LHgX(2) (L = phosphine donor, X = halogen); formation of a halide bridged dimer is presumably prevented by the extraordinarily sterically demanding ligand. A reaction mechanism for the formation of 5 and 8 is proposed which involves the formation of mercury complexes of 1 as the initial step.