Monoligand Zn(II) Complexes:  Ab Initio Benchmark Calculations and Comparison with Density Functional Theory...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Inorganic Chemistry

Background:

• Zinc(II) complexes are crucial in various chemical and biological systems.
• Accurate theoretical modeling of Zn(II) complexes is essential for understanding their properties.
• Density functional theory (DFT) methods are widely used but require careful validation.

Purpose of the Study:

• To systematically evaluate the performance of five DFT functionals (PW91, PBE, B3LYP, MPWLYP1M, TPSS) for Zn(II) complexes.
• To compare DFT results with high-level ab initio wave function methods (MP2, CCSD(T)).
• To analyze the key factors governing metal-ligand interactions in Zn(II) systems.

Main Methods:

• Ab initio correlated wave function calculations (MP2, CCSD(T)).
• Density functional theory (DFT) calculations using five different functionals.
• Employment of various basis sets, including specialized all-electron sets for zinc.
• Assessment of metal-ligand bond distances, binding energies, and proton affinities.

Main Results:

• All tested DFT functionals tended to overestimate metal-ligand bond distances and binding energies.
• The B3LYP and TPSS functionals demonstrated the best performance among the evaluated DFT methods.
• Induction and charge-transfer effects were identified as significant contributors to metal-ligand bonding.

Conclusions:

• B3LYP and TPSS offer a good balance of accuracy and computational cost for studying Zn(II) complexes.
• Accurate theoretical studies of Zn(II) complexes necessitate proper accounting for charge density polarization.
• The findings guide the selection of appropriate theoretical methods for future research on Zn(II) coordination chemistry.