[H(EtOH)2][{OsCl(η4-COD)}2(μ-H)(μ-Cl)2] as an intermediate for the preparation of [OsCl2(COD)]x and its activity as an ionic hydrogenation and etherification catalyst

Complex [H(EtOH)(2)][{OsCl(eta(4)-COD)}(2)(mu-H)(mu-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(eta(4)-COD)(CH3CN)(2) (3). On the other hand, treatment of 1 with acetonitrile affords the neutral dimer {Os(CH3CN)(eta(4)-COD)}(mu-H)(mu-Cl)(2){OsCl(eta(4)-COD)} (4), which has been characterized by X-ray diffraction analysis. The reaction of 4 with triisopropylphosphine gives {Os(Pi-Pr-3)(eta(4)-COD)}(mu-H)(mu-Cl)(2){OsCl(eta(4)-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.