Effective Computation of Coupling Force Constants: Metal Carbonyls as a Test Case

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Chemical Physics

Background:

• Electron delocalization is crucial for understanding chemical bonding.
• Metal carbonyl complexes exhibit complex electronic structures.
• Accurate calculation of coupling constants is essential for theoretical chemistry.

Purpose of the Study:

• To develop an automated protocol for computing unique potential coupling constants.
• To evaluate the performance of modern density functional theory (DFT) methods against coupled cluster theory (CCSD(T)).
• To assess the utility of coupling compliance constants as descriptors for the Dewar-Chatt-Duncanson model in various metal carbonyl systems.

Main Methods:

• Implementation of a semiautomated algorithm for computing compliance coupling constants.
• Utilizing inverse covariant second derivatives for calculations.
• Testing multiple DFT functionals against CCSD(T) benchmarks.
• Application to a series of 3d and 5d metal carbonyl complexes and ions.

Main Results:

• The automated protocol efficiently computes unique potential coupling constants.
• DFT methods show varying degrees of reliability compared to CCSD(T) for compliance matrix elements.
• Coupling compliance constants demonstrate potential as descriptors for the Dewar-Chatt-Duncanson model.
• The COMPLIANCE code is updated with a robust, open-source algorithm.

Conclusions:

• The developed automated protocol offers an efficient route to unique potential coupling constants.
• The study provides insights into the accuracy of DFT methods for describing electron delocalization in metal carbonyls.
• Coupling compliance constants are validated as valuable descriptors for specific bonding models.