Activation and Deactivation of Cp*Ir(TsDPEN) Hydrogenation Catalysts in Water

The addition of H 3 PO 4 to Cp*Ir(TsDPEN‐H), where TsDPEN = H 2 NCHPhCHPhNTs – , is a simple method to obtain a water‐soluble hydrogenation catalyst capable of reducing aromatic ketones to their corresponding alcohols in aqueous solutions. Key to the reactivity is the low affinity of the coordinatively unsaturated [Cp*Ir(TsDPEN)] + for H 2 PO 4 – . Catalyst degradation proceeds via the protonation of the tosylamido ligand, as was established by the crystallographic characterization of the tosylamine complex [Cp*Ir(NCMe)(HTsDPEN)] 2+ .(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)