The effect of annulation and carbonylation on the electronic and ligating properties of remote N-heterocyclic carbenes (rNHCs) has been studied quantum-chemically. The thermodynamic stability of these complexes has been assessed on the basis of their hydrogenation and stabilization energies, while HOMO-LUMO gaps are used to measure the kinetic stabilities. Annulated/carbonylated rNHCs are found to be weaker σ donors but better π acceptors compared with the parent rNHCs. The reactivity of these rNHCs has been studied by evaluating their nucleophilicity and electrophilicity indices. The nucleophilicity values are in good agreement with the σ basicities of all of the rNHCs. The (31)P NMR chemical shifts of the corresponding rNHC-phosphinidene adducts have been calculated and found to correlate well with the π acidities of these rNHCs.
An eco-friendly method for the oxidative transformation of alcohols to their corresponding carbonyl compounds by using g-C 3 N 4 @CuO as a photoactive heterogeneous catalyst has been developed. The catalyst was characterized by SEM-EDX, TEM, BET surface area measurements, powder XRD, FTIR, photoluminescence and UV-Vis spectroscopy. It was found to be very effective for the conversion of both primary and secondary alcohols into aldehydes and ketones with excellent yields using tert-butyl hydrogen peroxide (TBHP) as oxidant at room temperature in the presence of visible light in aqueous medium. The catalyst can be separated from the reaction mixture by simple centrifugation and reused up to five cycles without significant loss in activity.
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