191164-04-2Relevant academic research and scientific papers
The Os(CO)(PiPr3)2 unit as a support for the transformation of two alkyne molecules into new organometallic ligands
Buil, María L.,Esteruelas, Miguel A.,López, Ana M.,O?ate, Enrique
, p. 3169 - 3177 (2008/10/08)
In 2-propanol, the C-C triple bond of one of the two alkynyl ligands of the complex Os-(C2Ph)2(CO)(PiPr3)2 (1) can be broken by water to give Os(CH2Ph)(C2Ph)(CO)2(PiPr 3)2 (2). The reaction involves a metal-promoted, hydration-disproportionation of the transformed alkynyl ligand catalyzed by the solvent. Thus, the treatment of 1 with H218O yields Os(CH2-Ph)(C2Ph)(C18O)(CO)(PiPr 3)2 (2-18O), and the reaction of 1 with water in the presence of deuterated 2-propanol (iPrOD-d8) affords Os(CD2Ph)(C2Ph)(CO)2(PiPr 3)2 (2-d2). In methanol and in the presence of trifluoroacetic acid, complex 2 isomerizes into the osmaindene derivative Os{C(CH2Ph)=CHC6H4}(CO)2(P iPr3)2 (3). The structure of 3 has been determined by X-ray diffraction. The geometry around the osmium atom can be described as a distorted octahedron with the two triisopropylphosphine ligands occupying two relative trans positions. The remaining perpendicular plane is formed by the carbonyl ligands mutually cis disposed and the metallacycle, which forms a planar five-membered ring with the osmium atom. In methanol-d4, complex 2 reacts with CF3COOD to give OS{C(CH2Ph)=CDC6H4}(CO)2(P iPr3)2 (3-d1) and 3 in a 2.5:1 molar ratio. Complex 2 also reacts with HBF4. The reaction leads to a mixture of 3 and the π-allyl complex [Os{η3-CH(Ph)CHCHPh}(CO)2(PiPr 3)2]BF4 (4), which is a result from the addition of the proton from the acid and the carbon-carbon coupling of the benzyl and alkynyl ligands of 2. Similar to 2, complex 2-d2 reacts with HBF4 to give a mixture of Os{C(CD2Ph)=CHC6H4}(CO)2(P iPr3)2 (3-d2) and [Os{η3-CD(Ph)CDCHPh}(CO)2-(PiPr 3)2] BF4 (4-d2). On the basis of the isotope labeling experiments, the mechanisms of the above-mentioned transformations are discussed.
