Bond orders of the diatomic molecules

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Materials Science

Background:

• Bond order is crucial for understanding chemical properties and reactivity.
• Diatomic molecules are fundamental in atmospheric, biochemical, and industrial chemistry.
• Existing methods for bond order calculation lack comprehensive analysis, especially concerning semicore electron effects.

Purpose of the Study:

• To quantum-mechanically calculate bond orders for a large set of diatomic molecules and ions (288 total).
• To investigate the influence of semicore electrons on bond orders.
• To develop and apply a novel first-principles method, Bond Order Component Analysis (BOCA), for detailed bond order analysis.

Main Methods:

• Quantum mechanical calculations of bond orders for 288 diatomic species.
• Development of the Bond Order Component Analysis (BOCA) method for orbital-independent bond order decomposition.
• Application of BOCA to period 2 homodiatomics, Cr2, Mo2, ClO, ClO-, and Mo2(acetate)4 using Manz's bond order equation and DDEC6 partitioning.

Main Results:

• Established correlations between bond orders and bond energies for homodiatomics within the same chemical group.
• Quantified the weakening effect of diffuse semicore electrons on bond orders.
• Demonstrated the utility of BOCA in analyzing complex systems, e.g., Mo-Mo bond orders of 4.12 in Mo2 and 1.46 in Mo2(acetate)4.
• Developed a quantitative heuristic model for period 2 homodiatomic bond orders, including s-p mixing effects.

Conclusions:

• The study provides a robust computational framework for bond order analysis, enhancing understanding of chemical bonding.
• BOCA offers insights into the role of electronic structure, particularly semicore electrons, in determining bond characteristics.
• The findings and developed models serve as valuable resources for both chemistry research and educational purposes.