Calculations of the 1 H and C chemical shifts as well as the 1 JC-H coupling constants were performed using Gaussian09 at the B3LYP/(aug)-cc-pVTZ//B3LYP/TZVP level, either in the gas phase or in solution, where solvent effects were incorporated using the IEFPCM polarizable continuum model. the %age of s character of the carbene's lone pair (%sLP) and of the C-H bond (%s(C-H)) were obtained via Natural Bond Orbital (NBO) analysis using NBO6 software, based on the B3LYP/TZVP electronic structure. The ETS-NOCV method was employed to decompose the X-H bond energy and estimate the carbene's σ-donation term, E ETS-NOCV . These calculations were performed using the ADF2021.105 software at the B3LYP/TZ2P//B3LYP/TZVP level. Further details on the computational methods used are provided in the Supporting Information.