The complexes (Terpy)Ru(Pyo)2(OH2) and (Terpy)Ru(Pyr)2(OH2) (where Pyo=2-pyridinonate and Pyr=2-pyrrolidinonate) are precatalysts for ketone transfer hydrogenation. ESI-MSMS studies on the catalytic reactions identified the catalytic intermediates to be dimers within a ligand exchange manifold from the precatalysts and suggested that the active complexes are actually mixed-valent. We have modified our tandem borylation, Suzuki-coupling polypyridine synthesis to conveniently link chloroterpyridines directly or through spacer groups into bisterpyridine ligands that could bind two ruthenium atoms. These ligands react with (cymene)Ru(AziH)Cl2 (AziH=7-azaindole) and K2RuCl5(NO), and the resulting complexes subsequently react with Pyo or Azi to form ruthenium dimers some of which catalyze ketone transfer hydrogenation. A survey of these complexes and their catalytic activity will be presented.

Dimeric design strategy for transer hydrogenation catalysts

243rd National Meeting (2012)

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