Complex [H(EtOH)2][{OsCl(η4-COD)}2(μ-H)(μ-Cl)2] (1) reacts with 1-hexene, acetone, and acetophenone to give the corresponding reduced organic substrates and the osmium polymer [OsCl2(COD)]x (2, COD = 1,5-cyclooctadiene), which regenerates 1 in ethanol. The reaction of 2 with acetonitrile leads to the mononuclear derivative OsCl2(η4-COD)(CH3CN)2 (3). On the other hand, treatment of 1 with acetonitrile affords the neutral dimer {Os(CH3CN)(η4-COD)}(μ-H)(μ-Cl)2{OsCl(η4-COD)} (4), which has been characterized by X-ray diffraction analysis. The reaction of 4 with triisopropylphosphine gives {Os(Pi-Pr3)(η4-COD)}(μ-H)(μ-Cl)2{OsCl(η4-COD)} (5). Complex 1 is an active catalyst for the ionic hydrogenation of aldehydes and ketones, using 2-propanol as hydrogen source. The reductions of aromatic compounds are easier than those of aliphatic ones, and the hydrogenations of aldehydes are also easier than those of ketones. Complex 1 also promotes the alcohol etherification and one-pot synthesis of isopropyl ethers starting from 2-propanol and the corresponding aldehyde or ketone through catalytic hydrogenation−etherification tandem processes.

Financial support from the MEC of Spain (Proyect CTQ2005-00656) and Consolider Ingenio 2010 (CDS2007-00006) is acknowledged. C.G.-Y. thanks the Spanish MEC and the University of Zaragoza for funding through the “Ramón y Cajal” program.

Peer reviewed