Complexes of the platinum metals. Part 32. Synthesis and chemistry of some iridium sulphonate derivatives

Abstract

Sulphonic acids RSO₃H (R = CF₃, CH₃, or C₆H₄CH₃-p) react with mer-[IrH₃(PPh₃)₃], [IrCl(CO)(PPh₃)₂], and [IrH (CO)(PPh₃)₃] to afford the products [IrH₂(O₃SR)(PPh₃)₃], [IrH(Cl)(O₃SR)(CO)(PPh₃)₂], and [lrH₂(CO)(PPh₃)₃][O₃SR] respectively. Under more vigorous conditions the last reaction yields the bis(sulphonate) complexes [IrH(O₃SR)₂(CO)(PPh₃)₂]. The lability of the monodentate sulphonate ligands has been demonstrated by the substitution reactions of [lrH₂(O₃SR)(PPh₃)₃] with a variety of neutral donor ligands. Products readily obtained in this manner include [IrH₂(CH₃CN)(PPh₃)₃][O₃SR], [IrH₂L₂(PPh₃)₂][O₃SR][L = pyridine, 4- methylpyridine, or P(OPh)₃; L₂= 2,2′-bipyridyl, 1, 10-phenanthroline, ethylenediamine, or o-NH₂-C₆H₄NH₂], and trans-[IrH₂(Ph₂PCH₂PPh₂)₂][O₃SR]. Carbonylation of [IrH₂(O₃SCF₃)(PPh₃)₃] affords the tricarbonyl salt [Ir(CO)₃(PPh₃)₂][O₃SCF₃] whereas under similar conditions the precursors [IrH₂(O₃SR)(PPh₃)₃](R = CH₃ or C₆H₄CH₃-p) yield the dihydride salts [IrH₂(CO)(PPh₃)₃][O₃SR]. Many of the complexes isolated were solvated by H-bonded molecules of sulphonic acids. Stereochemical assignments based on ¹H, ¹⁹F, and ³¹P n.m.r. data are given for all the new products reported.