Theoretical analysis on the formation and nitric oxide release of N‐heterocyclic carbene nitric oxide radicals

Abstract

AbstractThe theoretical study on the fixation and release of nitric oxide (NO) by N‐heterocyclic carbenes (NHCs) is explored by utilizing a multivariate linear regression approach. We utilized data‐driven tools to establish correlations between molecular descriptors of NHC and reaction outputs of the formation and NO release of NHC nitric oxide radicals (NHCNOs). A key electronic parameter, the singlet‐triplet energy gap (ΔEST), plays a pivotal role in the thermodynamics of NHCNO formation (ΔGf) and NO release (ΔGr). The activation energy models highlight HOMO energy level (EHOMO), C–N bond length (dC–N), and NBO charge on N atom (qNBON) as crucial factors for the formation of NHCNO (ΔG‡f), while the activation energy for the NO release (ΔG‡r) significantly correlates with free energy difference (ΔGr), resulting a strong ΔEST dependency. This study provides valuable insights into the thermodynamics and kinetics of NHCNO processes, offering predictive capabilities to design NHCs tailored for NO release.