Olefin‐Stabilized Cobalt Nanoparticles for C=C, C=O, and C=N Hydrogenations

• Published in: Chemistry : a European journal 2018-03, Vol.24 (14), p.3403-3407
• Main Authors: Sandl, Sebastian, Schwarzhuber, Felix, Pöllath, Simon, Zweck, Josef, Jacobi von Wangelin, Axel
• Format: Article
• Language: English
• Subjects: Alkenes; Carbonyl compounds; Carbonyls; Catalysis; Catalysts; Chemistry; Cobalt; Coordination compounds; Hydrogenation; hydrogenations; Imines; ketones; Nanoparticles
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201705366

The development of cobalt catalysts that combine easy accessibility and high selectivity constitutes a promising approach to the replacement of noble‐metal catalysts in hydrogenation reactions. This report introduces a user‐friendly protocol that avoids complex ligands, hazardous reductants, special reaction conditions, and the formation of highly unstable pre‐catalysts. Reduction of CoBr2 with LiEt3BH in the presence of alkenes led to the formation of hydrogenation catalysts that effected clean conversions of alkenes, carbonyls, imines, and heteroarenes at mild conditions (3 mol % cat., 2–10 bar H2, 20–80 °C). Poisoning studies and nanoparticle characterization by TEM, EDX, and DLS supported the notion of a heterotopic catalysis mechanism. This report introduces a user‐friendly protocol for the development of cobalt catalysts that avoids complex ligands, hazardous reductants, special reaction conditions, and the formation of highly unstable pre‐catalysts. Reduction of CoBr2 with LiEt3BH in the presence of alkenes resulted in a hydrogenation catalyst which effected clean conversions of alkenes, carbonyls, imines, and heteroarenes at mild conditions (3 mol % cat., 2–10 bar H2, 20–80 °C). Poisoning studies and nanoparticle characterization supported the notion of a heterotopic catalysis mechanism.