677735-95-4Relevant academic research and scientific papers
Dehydrogenation of a Coordinated Alkylphosphine as a method to Prepare Cyclopentadienyl-α-alkenylphosphine-osmium Complexes
Baya, Miguel,Buil, Maria L.,Esteruelas, Miguel A.,Onate, Enrique
, p. 1416 - 1423 (2004)
The π-alkyne complex Os(η5-C5H 5)Cl(η2-PhC≡CPh)(PiPr3) (2) has been prepared by a two-step procedure involving the oxidative addition of H2 to Os(η5-C5H5)Cl(P iPr3)2 (1) and the subsequent reaction of the resulting dihydride with diphenylacetylene. In methanol, complex 2 evolves to give the isopropenyldi(isopropyl)phosphine derivative Os(η 5-C5H5)Cl{[η2-CH 2=C(CH3)]PiPr2} (4) and Z-stilbene, by hydrogen transfer from one isopropyl group of the triisopropylphosphine to diphenylacetylene. When the hydrogen transfer reaction is carried out in the presence of KPF6, the cationic Z-stilbene compound [Os(η 5-C5H5){η 2-(Z)-PhCH=CHPh}{[η2-CH2=C(CH 3)]PiPr2}]PF6 (5) is formed. The isopropenyldi(isopropyl)-phosphine ligand of 4 and 5 shows hemilabile properties. The hemilabile character of the isopropenyl substituent of the phosphine of 4 is revealed by the reaction of this complex with H2, which yields an equilibrium mixture of the starting compound and the transoiddihydride OsH2(η5-C5H 5)Cl{PiPr2[C(CH3)=CH2]} (6). The hemilabile character of the phosphine of 5 is shown in the reaction of this compound with MeLi, which affords OsH(η5-C5H 4CH3){η2-(Z)-PhCH=CHPh}{P iPr2[C(CH3)=CH2]} (7). In the solid state and in solution the Z-stilbene ligand of 7 isomerizes to give OsH(η5-C5H4CH3){η 2-(E)-PhCH=CHPh}{PiPr2-[C(CH 3)=CH2]} (8). Complexes 5 and 8 have been characterized by X-ray diffraction analysis.
