The Os(CO)(PiPr3)2 Unit as a Support for the Transformation of Two Alkyne Molecules into New Organometallic Ligands

Abstract

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(PiPr3)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(CH2Ph)(C2Ph)(C18O)(CO)(PiPr3)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(PiPr3)2 (2-d2). In methanol and in the presence of trifluoroacetic acid, complex 2 isomerizes into the osmaindene 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 me...