Solvent-stabilized alkylrhodium(III) hydride complexes: A special mode of reversible C-H bond elimination involving an agostic intermediate

Boris Rybtchinski, Leonid Konstantinovsky, Linda J.W. Shimon, Arkadi Vigalok, David Milstein

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38 Citations (Scopus)

Abstract

Reaction of the complex [Rh(coe)2(solv)n]BF4 (coe = cyclooctene) with the phosphane 1-di-tert-butylphosphinomethyl-2,4,6-trimethylbenzene (1) results in selective C-H bond activation, yielding the spectroscopically characterized solvento complexes [(solv)nRhH{CH2C6H2(CH 3)2-[CH2P(tBu)2]}]BF4 (solv = acetone, 2a; THF, 2b; methanol, 2c). The stability of these complexes is solvent dependent, alcohols providing significant stabilization. Although cis-alkylrhodium hydride complexes containing labile ligands are generally unstable, 2a-c are stable at room temperature. Complex [(acetone)-(ketol)RhH{CH2C6H2(CH 3)2[CH2P(t-Bu)2]}]BF4 (2d, ketol = 4-hydroxy-4-methyl-2-pentanone, the product of acetone aldol condensation), crystallized from a solution of 2a in acetone and was structurally characterized. Unusual solvent- and temperature-dependent selectivity in reversible C-H bond elimination of these complexes, most probably controlled by a special mode of strong agostic interactions, is observed by spin saturation transfer experiments.

Original languageEnglish
Pages (from-to)3287-3292
Number of pages6
JournalChemistry - A European Journal
Volume6
Issue number17
DOIs
Publication statusPublished - Sep 1 2000

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Keywords

  • Agostic interactions
  • C-H activation
  • Eliminations
  • Hydrido complexes
  • Rhodium

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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