Catalytic activity in transfer hydrogenation using ruthenium (II) carbonyl complexes containing two 1,8-naphthyridine as N-monodentate ligands

• Published in: Inorganica Chimica Acta 2019-02, Vol.486, p.129-134
• Main Authors: Gajardo, Juana, Araya, Juan C., Ibáñez, Andrés, Guerchais, Véronique, Le Bozec, Hubert, Moya, Sergio A., Aguirre, Pedro
• Format: Article
• Language: English
• Subjects: 1,8-Naphthyridine complexes; Acetophenone; Carbonyls; Catalysis; Catalysts; Catalytic activity; Chemical Sciences; Crystal structure; Crystallography; Crystals; Homogeneous catalysis; Hydrogenation; Ligands; Ruthenium; Ruthenium (II); Ruthenium compounds; Selectivity; Single crystals; Substrates; Synthesis; Transfer hydrogenation
• ISSN: 0020-1693; 1873-3255; 0020-1693
• DOI: 10.1016/j.ica.2018.10.037

[Display omitted] •Ruthenium complexes containing polypyridine ligands are active catalysts in hydrogen transfer reactions.•The hydrogen transfer reaction is catalyzed by ruthenium 1,8-naphthyridine derivate complexes.•Ruthenium complexes containing 1,8-naphthyridine ligands show high conversions in ketones hydrogenation.•Ruthenium complexes containing polypyridine ligands are alternative catalysts in hydrogenation reactions.•1,8-Naphthyridine ligands coordinate in a monodentate fashion into the ruthenium monometallic complexes. A new series of novel complexes of type cis-[Ru(CO)2Cl2(L)2], L = 2-phenyl-1,8-naphthyridine, 2-(4′-nitrophenyl)-1,8-naphthyridine, 2-(4′-bromophenyl)-1,8-naphthyridine, 2-(4′-methylphenyl)-1,8-naphthyridine, 2-(3′-methoxyphenyl)-1,8-naphthyridine, 2-(2′-methoxyphenyl)-1,8-naphthyridine and 2-(4′-methoxyphenyl)-1,8-naphthyridine have been successfully synthesized and characterized. We found that the complexes can be directly synthesized from [RuCl2(CO)2]2 with high yield. The crystallographic structures of complex cis-[RuCl2(CO)2(2-(4′-methoxyphenyl)-1,8-naphthyridine-κN8)2] and cis-[RuCl2(CO)2(2-(2′-methoxyphenyl)-1,8-naphthyridine-κN8)2] have been established by X-ray single crystal diffraction studies, which indicate an octahedral geometry with two 1,8-naphthyridine ligands coordinated to the metal in a N-monodentate fashion. The ruthenium(II) complexes have been studied as catalysts in the transfer hydrogenation of acetophenone. We found that complexes show moderate activities and a 100% selectivity. The best turnover frequency (390 h−1) is found for cis-[RuCl2(CO)2(2-(4′-methoxyphenyl)-1,8-naphthyridine-κN8)2] when the substrate/catalysis ratio was 1000/1. The catalytic conditions were optimized using different substrate/catalyst and base/catalyst ratios.