Influence of cyclopentadienyl ring-tilt on electron-transfer reactions: Redox-induced reactivity of strained [2] and [3] Ruthenocenophanes

Andrew D. Russell, Joe B. Gilroy, Kevin Lam, Mairi F. Haddow, Jeremy N. Harvey, William E. Geiger, Ian Manners

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Abstract

In contrast to ruthenocene [Ru(h5-C5H5)2] and di-methylruthenocene [Ru(h 5-C5H4Me)2] (7), chemical oxidation of highly strained, ring-tilted [2]ruthenocenophane [Ru(η5-C5H4)2(CH2)2] (5) and slightly strained [3]ruthenocenophane [Ru(h5-C5H4)2(CH2)3] (6) with cationic oxidants containing the non-coordinating [B(C6F5)4]- anion was found to afford stable and isolable metal-metal bonded dicationic dimer salts [Ru(h5-C5H4)2(CH2)2]2[B(C6F5)4]2 (8) and [Ru(h5-C5H4)2-(CH2)3]2[B(C6F5)4]2 (17), respectively. Cyclic voltammetry and DFT studies indicated that the oxidation potential, propensity for dimerization, and strength of the resulting Ru-Ru bond is strongly dependent on the degree of tilt present in 5 and 6 and thereby degree of exposure of the Ru center. Cleavage of the Ru-Ru bond in 8 was achieved through reaction with the radical source [(CH3)2NC(S)S-SC(S)N(CH3)2] (thiram), affording unusual dimer [(CH3)2NCS2Ru(η5-C5H4)(η3-C5H4)C2H4]2[B(C6F5)4]2 (9) through a haptotropic η53 ring-slippage followed by an apparent [2 + 2] cyclodimerization of the cyclopentadienyl ligand. Analogs of possible intermediates in the reaction pathway [C6H5ERu(η5-C5H4)2C2H4] [B(C6F5)4] [E = S (15) or Se (16)] were synthesized through reaction of 8 with C6H5E-EC6H5 (E = S or Se).

Original languageEnglish
Pages (from-to)16216-16227
Number of pages12
JournalChemistry - A European Journal
Volume20
Issue number49
DOIs
Publication statusPublished - Jan 12 2014

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Keywords

  • Electron-transfer reactions
  • Organometallic chemistry
  • Ruthenium

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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