Joint Isotherm Calorimetric Titration–DFT Investigation of the Demethoxy-Amination of Fischer Carbenes

•Enthalpies of amino-demethoxylation of Fischer carbenes measured in PhCl are mostly metal independent•ITC experiments carried out in chlorobenzene give reaction enthalpies consistent with static DFT-D calculations that assume implicit solvation The thermochemistry of the aminolysis of three methoxy Fischer carbenes, pentacarbonyl(phenylmethoxyalkylidene)chromium(0), molybdenum(0) and tungsten(0), was studied experimentally and theoretically with three amines, namely benzylamine, aniline and 3-pyrroline. Enthalpies of reactions were all determined by Isotherm Calorimetric Titration (ITC) in chlorobenzene at 298.15 K, which provided in almost all cases values of ΔrH larger than -15 kcal/mol suggesting energetically favourable transformations for all amines except aniline. No significant dependence of the enthalpy of reaction upon the nature of the metal atom of the carbene complex was found. Further ITC experiments confirmed the partial second-order reaction in amine. All COSMO-DFT computed enthalpies of reaction (spanning ca. -5.5 kcal/mol up to -20 kcal/mol) were found to be in excellent agreement with experimental values, while calculated Gibbs free energies suggested spontaneous processes for all reactions except the one with aniline. The thermochemistry of the aminolysis of a series of Cr-, Mo-, and W-Fischer carbenes was determined and confronted to static DFT-D computations. [Display omitted] .