New cyclopentadienylosmium derivatives prepared from the five-coordinate complex [OsHCl(CO)(PPr(i)3)(2)]

The reaction of [OsHCl(CO)(PPr3i)(2)] (1) with cyclopentadiene in refluxing methanol affords the novel cyclopentadienylosmium(II) complex [OsH(eta(5)-C5H5)(CO)-(PPr3i)] (2). Reaction of 2 with CCl4 in pentane gives the chloro complex [Os(eta(5)-C5H5)Cl(CO)(PPr3i)] (3). The protonation of 2 with HBF4.Et(2)O leads to the transdihydridoosmium(IV) complex[OsH2(eta(5)-C(5)H5)(CO)(PPr3i)]-BF (4). Treatment of the chloro complex 3 with AgBF4 followed by the terminal alkyne phenylacetylene or 1-ethynhyl-1-cyclohexanol gives the stable vinylidene [Os-(eta(5)-C5H5){=C=C(H)Ph}(CO)(PPr3i)]BF4 (5) or vinylvinylidene [Os(eta(5)-C5H5){=C=C(H)C=CH(CH2)(3)CH2}(CO)-(PPr3i)]BF4 (6), respectively.