Comparison of the reactivity of M(allyl)(3) (M = Rh, Ir) with donor ligands

Reactions of M(allyl)(3) [M = Rh, Ir] with a variety of donor ligands have been investigated. While both complexes are unreactive toward "hard" N- and O-donor ligands, "soft" ligands such as tolylisothiocyanate, tertiary phos phines, CO, and aryl isocyanides are readily added. Whereas ligand addition s to Rh(allyl)(3) are often accompanied by reduction of the Rh(III) center, analogous reactions with Ir(allyl)(3) afford stable trivalent products con taining sigma -allyl ligands. The molecular structures of several derivativ es are presented, including Ir(sigma -allyl)(pi -allyl)(2)(PPh3), Ir(sigma -allyl)(2)(pi -allyl)(PMe3)(2), and Ir(sigma -allyl)(3)(C dropN-2,6-Me2C6H3 )(3).