A computational study of oxidative addition of methane to M(OC2H4)3A for M = Re and Ta (where A may act as an ancillary ligand) was performed. The choice of ancillary ligands has been made based on their electronic properties: A = B or Al (Lewis acid), CH or SiH (electron precise), N (σ-donor) and P (σ-donor/π-acid), to understand that how variation in A can alter the kinetics and thermodynamic of oxidative addition. For Ta-complexes DFT and MP2 studies were performed while for Re-complexes MP2, CCSD(T) and MCSCF calculations were carried out. Initial DFT study on oxidative addition of methane to Ta(OC2H4)3A revealed that transition state having H trans to A is kinetically more favored over the other with CH3 trans to A. For other methods, we focused on the most favored transition states and corresponding products. Results showed that in all cases upon moving from electron-deficient (B, Al) to electron-rich moieties (P and N) the computed C−H activation barrier for the kinetic product decreases significantly. Our simulations indicate that the effect of changing the ancillary ligand is more significant than changing the metal from Ta to Re.

Effect of ancillary ligands (A) on oxidative addition of CH4 to MIII complexes: M = Ta, Re; A = B, Al, CH, SiH, N, P using DFT, MP2, CCSD(T) and MCSCF methods

254th National Meeting (2017)

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