Lewis Base-Assisted Hydride-Carbyne to Olefin Transformation versus Carbene Formation
摘要:
Complex [OsH(eta(5)-C5H6)( dropC-CH2Ph)((PPr3)-Pr-i)BF4 (1) reacts with KBr in tetrahydrofuran to give the a pi CH2=CHPh)(PiPr3), -olefin derivative OsBr(eta(5)-C5H5)(eta(2)-CH2=CHPh)(PPr3)-Pr-i) which has been characterized by X-ray diffraction analysis. Similarly, the reaction of [OsH(eta5-C5H5)( dropC-CD2-Ph)((PPr3)-Pr-i)]BF4 (1-d2) with KBr leads to the pi-dideuterated-olefin complex. On the basis of the deuterium distribution in this complex and the previously reported P(OMe)(3)-assisted hydride-carbyne to carbene transformation, the mechanism of the Br-assisted hydride-carbyne to olefin transformation is discussed.
Hydride−Carbyne to Carbene Transformation in a Cyclopentadienyl−Osmium Complex: An Alternative to the Single Hydride−Cα Migration
摘要:
Complexes OsH(eta(5)-C5H5)(Cequivalent toCPh)(EPh3)-((PPr3)-Pr-i) [E = Si (1), Ge (2)] react with 2.0 equiv of HBF4.OEt2 to give [OsH(eta(5)-C5H5)(equivalent toC-CH2Ph)((PPr3)-Pr-i)]-BF4 (3). Treatment of 3 with KOH affords OsH(eta(5)-C5H5)(=C=CHPh)((PPr3)-Pr-i) (5) in equilibrium with the metalated species OsH(eta(5)-C5H5)(o-C6H4CH=CH)((PPr3)-Pr-i) (7) (DeltaHdegrees = -3.6 +/- 0.2 kcal mol(-1) and DeltaSdegrees = -10.8 +/- 1.9 cal K-1 mol(-1) for the formation of 7). The addition of P(OMe)3 to the solution of the isomeric mixture leads to Os(eta(5)-C5H5{(E)-CH=CHPh}{P(OMe)(3)}((PPr3)-Pr-i) (8), which reacts with HBF4.OEt2 to give [Os(eta(5)-C5H5(=CHCH2Ph){P(OMe)(3)}((PPr3)-Pr-i)]BF4 (4).