Preparation and some reactions of (σ-aryl)(thiocarbonyl)bis(triphenylphosphine)-rhodium(I) and -iridium(I): a comparative study with the analogous carbonyl derivatives

Abstract

Complexes of the type [MR(CS)(PPh₃)₂][M = Rh, R = C₆F₅(1a) or C₆Cl₅(2a); M = Ir, R = C₆F₅(1b) or C₆Cl₅(2b)] have been prepared from [MCl(CS)(PPh₃)₂] and the corresponding aryl-lithium reagents or aryl-magnesium halides. None of the prepared complexes gives a dioxygen adduct. Complexes (1b) and (2b) react with hydrochloric acid to give six-co-ordinate hydridoiridium(III) species; the reaction is reversible and, by refluxing the adducts in ethanol, the starting iridium(I) complexes are regenerated. Complexes (1a) and (2a) react with HCl giving [RhCl(CS)(PPh₃)₂]. The halogens react with (1b) and (2b) giving, in some cases, well defined adducts. The iridium(III) adduct [Ir(C₆F₅)(CS)I₂(PPh₃)₂] reacts with p-toluidine to give the isocyanide complex [Ir(C₆F₅)-(CNC₆H₄Me-p)I₂(PPh₃)₂] by nucleophilic attack of the amine on the carbon atom of CS. Complex (1b) reacts with Mel giving the thiocarbene [Ir(C₆F₅){CMe(SMe})I₂(PPh₃)₂]; the mechanism of this reaction is discussed. Mercury(II) chloride reacts with (1b) to give [Ir(C₆F₅)Cl(CS)(HgCl)(PPh₃)₂]. The i.r. and ¹H n.m.r. spectra of the complexes are discussed.