Direct observation of reductive elimination of MeX (X = Cl, Br, I) from RhIII complexes: Mechanistic insight and the importance of sterics

Moran Feller; Yael Diskin-Posner; Gregory Leitus; Linda J W Shimon; David Milstein

doi:10.1021/ja401852c

Direct observation of reductive elimination of MeX (X = Cl, Br, I) from RhIII complexes

Mechanistic insight and the importance of sterics

Moran Feller, Yael Diskin-Posner, Gregory Leitus, Linda J W Shimon, David Milstein

Weizmann Institute of Science, Israel

Research output: Contribution to journal › Article

28 Citations (Scopus)

Abstract

Rare cases of directly observed reductive elimination (RE) of methyl halides from Rh^III complexes are described. Treatment of the coordinatively unsaturated complexes [(^tBuPNP)Rh(CH ₃)X][BF₄] (1-3, X = I, Br, and Cl; ^tBuPNP = 2,6-bis-(di-tert-butylphosphinomethyl)pyridine) with coordinating and noncoordinating compounds results in the formation of the corresponding free methyl halides and Rh^I complexes. The rate increase of CH ₃I and CH₃Br RE in the presence of polar aprotic solvents argues in favor of an S_N2 RE mechanism. However, the RE of CH ₃Cl is faster in polar protic solvents, which argues in favor of a concerted C-Cl RE. The RE of methyl halides from complexes 1-3 is induced by steric factors, as treatment of the less bulky complexes [(ⁱPrPNP) Rh(CH₃)X][BF₄] (19-21; X = I, Br, Cl, respectively) with coordinating compounds leads to the formation of the adducts complexes rather than RE of the methyl halides. The accumulated evidence suggests that the RE process is nonassociative.

Original language	English
Pages (from-to)	11040-11047
Number of pages	8
Journal	Journal of the American Chemical Society
Volume	135
Issue number	30
DOIs	https://doi.org/10.1021/ja401852c
Publication status	Published - Jul 31 2013

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Observation

Lead compounds

Pyridine

pyridine

ASJC Scopus subject areas

Chemistry(all)
Catalysis
Biochemistry
Colloid and Surface Chemistry

Cite this

Feller, M., Diskin-Posner, Y., Leitus, G., Shimon, L. J. W., & Milstein, D. (2013). Direct observation of reductive elimination of MeX (X = Cl, Br, I) from RhIII complexes: Mechanistic insight and the importance of sterics. Journal of the American Chemical Society, 135(30), 11040-11047. https://doi.org/10.1021/ja401852c

Direct observation of reductive elimination of MeX (X = Cl, Br, I) from RhIII complexes : Mechanistic insight and the importance of sterics. / Feller, Moran; Diskin-Posner, Yael; Leitus, Gregory; Shimon, Linda J W; Milstein, David.

In: Journal of the American Chemical Society, Vol. 135, No. 30, 31.07.2013, p. 11040-11047.

Research output: Contribution to journal › Article

Feller, M, Diskin-Posner, Y, Leitus, G, Shimon, LJW & Milstein, D 2013, 'Direct observation of reductive elimination of MeX (X = Cl, Br, I) from RhIII complexes: Mechanistic insight and the importance of sterics', Journal of the American Chemical Society, vol. 135, no. 30, pp. 11040-11047. https://doi.org/10.1021/ja401852c

Feller M, Diskin-Posner Y, Leitus G, Shimon LJW, Milstein D. Direct observation of reductive elimination of MeX (X = Cl, Br, I) from RhIII complexes: Mechanistic insight and the importance of sterics. Journal of the American Chemical Society. 2013 Jul 31;135(30):11040-11047. https://doi.org/10.1021/ja401852c

Feller, Moran ; Diskin-Posner, Yael ; Leitus, Gregory ; Shimon, Linda J W ; Milstein, David. / Direct observation of reductive elimination of MeX (X = Cl, Br, I) from RhIII complexes : Mechanistic insight and the importance of sterics. In: Journal of the American Chemical Society. 2013 ; Vol. 135, No. 30. pp. 11040-11047.

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abstract = "Rare cases of directly observed reductive elimination (RE) of methyl halides from RhIII complexes are described. Treatment of the coordinatively unsaturated complexes [(tBuPNP)Rh(CH 3)X][BF4] (1-3, X = I, Br, and Cl; tBuPNP = 2,6-bis-(di-tert-butylphosphinomethyl)pyridine) with coordinating and noncoordinating compounds results in the formation of the corresponding free methyl halides and RhI complexes. The rate increase of CH 3I and CH3Br RE in the presence of polar aprotic solvents argues in favor of an SN2 RE mechanism. However, the RE of CH 3Cl is faster in polar protic solvents, which argues in favor of a concerted C-Cl RE. The RE of methyl halides from complexes 1-3 is induced by steric factors, as treatment of the less bulky complexes [(iPrPNP) Rh(CH3)X][BF4] (19-21; X = I, Br, Cl, respectively) with coordinating compounds leads to the formation of the adducts complexes rather than RE of the methyl halides. The accumulated evidence suggests that the RE process is nonassociative.",

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10.1021/ja401852c