biostudies-literatureNikol ATCarlsbergfondetDanmarks Frie ForskningsfondVillum FondenNovo Nordisk Fonden26209https://www.ebi.ac.uk/biostudies/studies/S-EPMC11527872biostudies-literatureUnknown14(1)Formic acid is one of the most promising candidates for the long-term storage of hydrogen in liquid form. Herein, we present a new collection of ruthenium pincer complexes of the general formula [RuHCl(POP)(PPh₃)] using commercially available or easy-to-synthesize tridentate xantphos-type POP pincer ligands. We applied these complexes in the dehydrogenation of formic acid to CO₂ and H₂ using the ionic liquid BMIM OAc (1-butyl-3-methylimidazolium acetate) as solvent under mild, reflux-free conditions. The best performing catalyst with respect to maximum turnover frequency, the literature-known complex [RuHCl(xantphos)(PPh₃)] Ru-1, produced a maximum turnover frequency of 4525 h^-1 with 74% conversion after 10 min at 90 °C and complete conversion (> 98%) occurring within 3 h. On the other hand, the best overall performing catalyst, the novel complex [RuHCl(iPr-dbfphos)(PPh₃)] Ru-2, facilitated full conversion within 1 h leading to an overall turnover frequency of 1009 h^-1. Moreover, catalytic activity was observed at temperatures as low as 60 °C. Only CO₂ and H₂ are observed in the gas phase, with no CO detected. High-resolution mass spectrometry suggests the presence of N-heterocyclic carbene complexes in the reaction mixture.Scientific reportsFormic acid dehydrogenation using Ruthenium-POP pincer complexes in ionic liquids.PMC11527872190491127-00172BCF20-0365NNF20OC0064560Nikol ATJorgensen MSBRabell BNielsen MLarsen RWfalseFormic acid dehydrogenation using Ruthenium-POP pincer complexes in ionic liquids.Formic acid is one of the most promising candidates for the long-term storage of hydrogen in liquid form. Herein, we present a new collection of ruthenium pincer complexes of the general formula [RuHCl(POP)(PPh₃)] using commercially available or easy-to-synthesize tridentate xantphos-type POP pincer ligands. We applied these complexes in the dehydrogenation of formic acid to CO₂ and H₂ using the ionic liquid BMIM OAc (1-butyl-3-methylimidazolium acetate) as solvent under mild, reflux-free conditions. The best performing catalyst with respect to maximum turnover frequency, the literature-known complex [RuHCl(xantphos)(PPh₃)] Ru-1, produced a maximum turnover frequency of 4525 h^-1 with 74% conversion after 10 min at 90 °C and complete conversion (> 98%) occurring within 3 h. On the other hand, the best overall performing catalyst, the novel complex [RuHCl(iPr-dbfphos)(PPh₃)] Ru-2, facilitated full conversion within 1 h leading to an overall turnover frequency of 1009 h^-1. Moreover, catalytic activity was observed at temperatures as low as 60 °C. Only CO₂ and H₂ are observed in the gas phase, with no CO detected. High-resolution mass spectrometry suggests the presence of N-heterocyclic carbene complexes in the reaction mixture.2024-01-01T00:00:00Z2024 Oct2025-04-05T09:14:19.924Z2025-04-05T09:14:19.924ZS-EPMC115278723948232310.1038/s41598-024-76782-3