Organometallics_Kircher2025_Ir-dihydrideComplexes_data

In this work, we utilize $^1$H benchtop nuclear magnetic resonance (NMR) spectroscopy (proton frequency 44.7 MHz) for real-time monitoring of spin-transfer catalysis, starting from an iridium-based organometallic precursor complex [Ir(IMes)(COD)Cl] (IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene, COD = cyclooctadiene) with hydrogen in solution. We identify two distinct activation pathways: first, via the formation of neutral intermediate complex [Ir(IMes)(COD)(H)$_2$Cl], and second, via the formation of charged complexes [Ir$^{+}$(IMes)(COD)(H)$_2$)R]Cl$^{-}$ (with R being bound ligands: acetonitrile, ammonia, or benzylamine). We conclude that the pathway direction is dominated by solvent polarity and explore SABRE (Signal Amplification by Reversible Exchange) of an acetonitrile solvent in the presence of a benzylamine co-ligand.These results are important for better understanding of the chemical dynamics in SABRE systems as well as for the fundamental physics experiments that require stable and long-lasting polarization of highly-concentrated molecules (e.g., those from the solvent itself).Fig1: solventACN_5mMIr_125mMBNNH2Fig2: solventACN_5mMIr, solventACN_5mMIr_50mMBNNH2, solventACN_5mMIr_100mMBNNH2, solventACN_5mMIr_125mMBNNH2, solventACN_5mMIr_150mMBNNH2, solventACN_5mMIr_250mMBNNH2, solventACN_5mMIr_387mMBNNH2Fig3: solventDCM_5mMIr_100mM15NBA, solventMOH_3mMIr_60mM15NH4OHNH3, solventDCM_3mMIr_extracted15NH4OHNH3from14MNH4OHinH2O)<br><br><br>