Stepwise metal-ligand cooperation by a reversible aromatization/ deconjugation sequence in ruthenium complexes with a tetradentate phenanthroline-based ligand

Robert Langer, Ido Fuchs, Matthias Vogt, Ekambaram Balaraman, Yael Diskin-Posner, Linda J.W. Shimon, Yehoshoa Ben-David, David Milstein

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)

Abstract

The synthesis and reactivity of ruthenium complexes containing the tetradentate phenanthroline-based phosphine ligand 2,9-bis((di-tert- butylphosphino)methyl)-1,10-phenanthroline (PPhenP) is described. The hydrido chloro complex [RuHCl(PPhenP)] (2) undergoes facile dearomatization upon deprotonation of the benzylic position, to give [RuH(PPhenP-H)] (4). Addition of dihydrogen to 4 causes rearomatization of the phenanthroline moiety to trans-[Ru(H)2(PPhenP)] (5), followed by hydrogenation of an aromatic heterocycle in the ligand backbone, to give a new dearomatized and deconjugated complex [RuH(PPhenP*-H)] (6). These aromatization/deconjugation steps of the coordinated ligand were demonstrated to be reversible and operative in the dehydrogenation of primary alcohols without the need for a hydrogen acceptor. This aromatization/deconjugation sequence constitutes an unprecedented mode of a stepwise cooperation between the metal center and the coordinated ligand. Obligation to cooperate: A dearomatization/deconjugation sequence, involving reversible hydrogenation of the ligand backbone, has been uncovered for the dihydrogen activation by ruthenium complexes with a tetradentate phenanthroline-based ligand. This unprecedented mode of stepwise cooperation between the metal center and the coordinated ligand is demonstrated to be reversible and operative in the dehydrogenation of primary alcohols without the need for a hydrogen acceptor (see scheme).

Original languageEnglish
Pages (from-to)3407-3414
Number of pages8
JournalChemistry - A European Journal
Volume19
Issue number10
DOIs
Publication statusPublished - Mar 4 2013

Keywords

  • cooperative effects
  • coordination chemistry
  • dehydrogenation
  • homogeneous catalysis
  • ruthenium

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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