Donor-driven conformational flexibility in a real-life catalytic dicopper(ii) peroxo complex

Area of Science:

• Computational Chemistry
• Bioinorganic Chemistry
• Catalysis

Background:

• Tyrosinase enzymes are crucial in biological systems, catalyzing hydroxylation reactions.
• Understanding the structure-activity relationship of synthetic tyrosinase models is key to developing efficient catalysts.
• The specific copper complex [Cu2O2{HC(3-tBuPz)2(Py)}2](2+) exhibits significant catalytic hydroxylation reactivity.

Purpose of the Study:

• To investigate the conformers of the real-life tyrosinase model [Cu2O2{HC(3-tBuPz)2(Py)}2](2+).
• To elucidate the donor competition between pyrazolyl and pyridinyl moieties within the copper complex.
• To dissect the electronic structure and interactions governing the catalytic activity of this system.

Main Methods:

• Density Functional Theory (DFT) studies, including second-order perturbation theory.
• Charge Decomposition Analysis (CDA) to understand electronic structure and bonding.
• Geometry optimizations and Time-Dependent DFT (TD-DFT) calculations for conformer analysis and prediction of experimental data (XAS distances, charge-transfer bands).

Main Results:

• Pyrazolyl units were identified as stronger electron donors than pyridinyl moieties in the bis(pyrazolyl)pyridinylmethane copper complexes.
• DFT calculations accurately predicted experimental data, including XAS distances and charge-transfer bands.
• CDA revealed that N-donor interactions to the copper core are highly stabilizing, with equatorial pyrazolyl interactions being more stabilizing than axial ones in certain conformers.

Conclusions:

• The study provides a detailed, unsimplified dissection of donor interplay and interactions in a real-life catalytic system.
• The extraordinary catalytic activity of the [Cu2O2{HC(3-tBuPz)2(Py)}2](2+) system is attributed to the subtle interplay of different donor moieties.
• Computational methods (DFT, CDA) are robust for predicting experimental data and elucidating electronic structures of complex bioinorganic models.