Synthesis and structural characterization of isomeric monocarbon (η-dicyclopentenyl)-closo-rhodacarboranes stabilized by the agostic bonding interaction

Pisareva, I. V.; Dolgushin, Fedor M.; Godovikov, Ivan A.; Chizhevsky, I. T.

doi:10.1016/j.inoche.2008.07.004

Cited by 6 publications

(1 citation statement)

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“…These chemical shifts are more downfield than those of terminal rhodium hydride complexes 23–25 and are similar to those of other metal complexes that contain norbornyl ligands with agostic interactions. 26–31 The 1 J C–H coupling constant of the agostic C–H bond of 5 ′ was ~60 Hz at −80 °C, as determined by 2D J -resolved 13 C NMR spectroscopic analysis. This value is significantly lower than those of the analogous free C–H bonds and agrees with the previously reported values for C–H bonds engaged in agostic interactions.…”

Section: Resultsmentioning

confidence: 91%

Mechanistic Studies on Rhodium-Catalyzed Enantioselective Silylation of Aryl C–H Bonds

Lee

Hartwig

2017

J. Am. Chem. Soc.

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Several classes of enantioselective silylations of C–H bonds have been reported recently, but little mechanistic data on these processes are available. We report mechanistic studies on the rhodium-catalyzed, enantioselective silylation of aryl C–H bonds. A rhodium silyl dihydride and a rhodium norbornyl complex were prepared and determined to be interconverting catalyst resting states. Kinetic isotope effects indicated that the C–H bond cleavage step is not rate-determining, but the C–H bond cleavage and C–Si bond-forming steps together influence the enantioselectivity. DFT calculations indicate that the enantioselectivity originates from unfavorable steric interactions between the substrate and the ligand in the transition state leading to the formation of the minor enantiomer.

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