Square-Planar Alkylidyne–Osmium and Five-Coordinate Alkylidene–Osmium Complexes: Controlling the Transformation from Hydride-Alkylidyne to Alkylidene

详细信息    查看全文

• 作者：María L. Buil ; Juan J. F. Cardo ; Miguel A. Esteruelas ; Enrique Oñate
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：August 3, 2016
• 年：2016
• 卷：138
• 期：30
• 页码：9720-9728
• 全文大小：543K
• 年卷期：0
• ISSN：1520-5126

文摘

Square-planar alkylidyne and five-coordinate alkylidene mixed ⁱPr₃P–Os–IPr (IPr = 1,3-bis(diisopropylphenyl)imidazolylidene) complexes have been discovered and characterized, and their formation has been rationalized. The cationic five-coordinate hydride-alkylidyne compounds [OsHX(≡CPh)(IPr)(PⁱPr₃)]OTf (X = Cl (1), F (4); OTf = CF₃SO₃) undergo deprotonation with KO^tBu to afford the trans-halide-alkylidyne square-planar derivatives OsX(≡CPh)(IPr)(PⁱPr₃) (X = Cl (2), F (5)). Oxidative addition of the C(sp)–H bond of phenylacetylene and methyl propiolate along the Cl–Os–CPh axis of 2 with the hydrogen atom directed to the alkylidyne leads to alkynyl-cis-hydride-alkylidyne intermediates, which rapidly evolve into the five-coordinate alkylidene complexes Os(C≡CR)Cl(═CHPh)(IPr)(PⁱPr₃) (R = Ph (6), CO₂Me (7)) as a consequence of the migration of the hydride from the metal center to the C_α atom of the alkylidyne. Oxidative addition of the C(sp)–H bond of methyl propiolate along the X–Os–CPh axis of 2 and 5 with the hydrogen atom directed to the halide gives the alkynyl-trans-hydride-alkylidyne derivatives OsH(C≡CCO₂Me)X(≡CPh)(IPr)(PⁱPr₃) (X = Cl (8), F (9)). Complex 8 evolves into 7. However, complex 9 containing the stronger π-donor fluoride is stable. The oxidative addition of HCl to 2 selectively yields the cis-hydride-alkylidyne compound OsHCl₂(≡CPh)(IPr)(PⁱPr₃) (10), which is also stable.