| Abstract
| - Deuteration of organic molecules using D2O as the deuterium source is affected with catalytic systemsbased on the ruthenium solvento hydride complex TpRu(PPh3)(CH3CN)H. The deuteration reactions canbe performed under Ar or H2. In the former case, the hydride ligand is rapidly deuterated by D2O, andin the course of the catalysis, D2O converts TpRu(PPh3)(CH3CN)D into the acetamido complex TpRu(PPh3)(D2O)(NDC(O)CH3), which at the later stage of the reaction generates two additional minor species,one of which is the partially deuterated carbonyl hydride species TpRu(PPh3)(CO)H(or D). All of thesecomplexes are, however, found to be inactive for the H/D exchange reactions between the organicmolecules and D2O. In the exchange reactions under H2, a mixture of the HD isotopomers,TpRu(PPh3)H3-xDx, of the dihydrogen hydride complex TpRu(PPh3)(H2)H are the active species. On thebasis of our previous work on the TpRu(PPh3)(CH3CN)H-catalyzed H/D exchange reactions betweendeuterated organic molecules and CH4, it is proposed that TpRu(PPh3)(CH3CN)D and TpRu(PPh3)(H3-x)Dxexchange their deuteride ligands Ru−D with R−H via the intermediacies of the η2-R−H(or D) andη2-H−H(or D) σ-complexes; the Ru−H bonds thus formed after the exchange are deuterated by D2O toregenerate the metal deuterides. The solvento complex TpRu(PPh3)(CH3CN)D under Ar is suggested tobe more active than TpRu(PPh3)(H3-x)Dx under H2 for the H/D exchange reactions because the formerreacts more readily with the organic molecule R−H to generate the η2-R−H σ-complex due to higherlability of the CH3CN ligand in comparison with the dihydrogen or hydrogen−deuterium ligand ofTpRu(PPh3)(H3-x)Dx. The acetamido complex TpRu(PPh3)(H2O)(NHC(O)CH3) was independently preparedby refluxing a THF solution of TpRu(PPh3)(CH3CN)H containing excess water for 24 h, and its molecularstructure was determined by X-ray crystallography. Theoretical calculations at the Becke3LYP level ofDFT theory have been performed to study the reaction of TpRu(PPh3)(CH3CN)H with H2O that leads tothe formation TpRu(PPh3)(H2O)(NHC(O)CH3). It is shown that the hydration reaction is promoted by aRu−H···H−OH dihydrogen-bonding interaction between the hydride ligand and the attacking watermolecule. An explanation for the failure of the chloro analogue TpRu(PPh3)(CH3CN)Cl to react withwater to form the acetamido complex is also provided.
- The Tp−ruthenium solvento hydride complex TpRu(PPh3)(CH3CN)H (1) catalyzes H/D exchange reactions between organic compounds and D2O; in the course of catalysis, 1 is converted to the acetamido complex TpRu(PPh3)(H2O)(NH(CO)CH3)
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