Assembly of an Allenylidene Ligand, a Terminal Alkyne, and an Acetonitrile Molecule: Formation of Osmacyclopentapyrrole Derivatives
Autores: Tamara Bolaño, Ricardo Castarlenas, Miguel A. Esteruelas y Enrique Oñate
Ref. revista: Journal of the American Chemiscal Society, 128, 3965-3973, (2006)
Treatment in acetonitrile at -30 °C of the hydride-alkenylcarbyne complex [OsH(tCCHdCPh2)(CH3CN)2(PiPr3)2][BF4]2 (1) with tBuOK produces the selective deprotonation of the alkenyl substituent of the carbyne and the formation of the bis-solvento hydride-allenylidene derivative [OsH(=C=C=CPh2)(CH3CN)2(PiPr3)2]BF4 (2), which under carbon monoxide atmosphere is converted into [Os(CH=C=CPh2)(CO)(CH3CN)2(PiPr3)2]BF4 (3). When the treatment of 1 with tBuOK is carried out in dichloromethane at room temperature, the fluoro-alkenylcarbyne [OsHF(tCCHdCPh2)(CH3CN)(PiPr3)2]BF4 (4) is isolated.
Complex 2 reacts with terminal alkynes. The reactions with phenylacetylene and cyclohexylacetylene afford [Os{(E)-CHdCHR}(dCdCdCPh2)(CH3CN)2(PiPr3)2]BF4 (R ) Ph (5), Cy (6)), containing an alkenyl ligand beside the allenylidene, while the reaction with acetylene in dichloromethane at -20 °C gives the hydrideallenylidene- ð-alkyne [OsH(dCdCdCPh2)(è2-HCtCH)(PiPr3)2]BF4 (7), with the alkyne acting as a fourelectron donor ligand. In acetonitrile under reflux, complexes 5 and 6 are transformed into the osmacyclopentapyrrole compounds [Os{CdC(CPh2CRdCH)CMedNH}(CH3CN)2]BF4 (R ) Ph (8), Cy (9)),
as a result of the assembly of the allenylidene ligand, the alkenyl group, and an acetonitrile molecule. The X-ray structures of 2, 5, and 8 are also reported.
Treatment in acetonitrile at -30 °C of the hydride-alkenylcarbyne complex [OsH(tCCHdCPh2)(CH3CN)2(PiPr3)2][BF4]2 (1) with tBuOK produces the selective deprotonation of the alkenyl substituent of the carbyne and the formation of the bis-solvento hydride-allenylidene derivative [OsH(=C=C=CPh2)(CH3CN)2(PiPr3)2]BF4 (2), which under carbon monoxide atmosphere is converted into [Os(CH=C=CPh2)(CO)(CH3CN)2(PiPr3)2]BF4 (3). When the treatment of 1 with tBuOK is carried out in dichloromethane at room temperature, the fluoro-alkenylcarbyne [OsHF(tCCHdCPh2)(CH3CN)(PiPr3)2]BF4 (4) is isolated.
Complex 2 reacts with terminal alkynes. The reactions with phenylacetylene and cyclohexylacetylene afford [Os{(E)-CHdCHR}(dCdCdCPh2)(CH3CN)2(PiPr3)2]BF4 (R ) Ph (5), Cy (6)), containing an alkenyl ligand beside the allenylidene, while the reaction with acetylene in dichloromethane at -20 °C gives the hydrideallenylidene- ð-alkyne [OsH(dCdCdCPh2)(è2-HCtCH)(PiPr3)2]BF4 (7), with the alkyne acting as a fourelectron donor ligand. In acetonitrile under reflux, complexes 5 and 6 are transformed into the osmacyclopentapyrrole compounds [Os{CdC(CPh2CRdCH)CMedNH}(CH3CN)2]BF4 (R ) Ph (8), Cy (9)),
as a result of the assembly of the allenylidene ligand, the alkenyl group, and an acetonitrile molecule. The X-ray structures of 2, 5, and 8 are also reported.