Density functional and Ab initio study of Cr(CO)n (n = 1-6) complexes.

Area of Science:

• Inorganic Chemistry
• Computational Chemistry
• Quantum Chemistry

Background:

• Chromium carbonyl complexes (Cr(CO)n) are crucial in inorganic chemistry.
• Understanding ligand dissociation pathways is vital for predicting reactivity.
• Previous theoretical studies have provided insights but require further refinement.

Purpose of the Study:

• To comprehensively investigate the electronic structure and stability of Cr(CO)n (n=1-6) across all spin states.
• To elucidate the ground state properties of chromium carbonyl fragments.
• To provide accurate theoretical data for experimental validation.

Main Methods:

• Utilized density functional theory (DFT) and high-level ab initio methods.
• Performed geometry optimizations and vibrational frequency calculations.
• Calculated sequential bond dissociation energies (BDE) and CO binding energies.

Main Results:

• Ground states of Cr(CO)6, Cr(CO)5, and Cr(CO)4 (singlets) align with existing data.
• Identified a potential quintet ground state for Cr(CO)3 with C2v symmetry.
• Determined a linear septet ground state for Cr(CO)2, differing from previous DFT predictions.
• Observed partial C-O bond weakening in nonet states of Cr(CO)2 and CrCO.

Conclusions:

• The study refines the understanding of chromium carbonyl fragmentation.
• New ground state assignments for Cr(CO)3 and Cr(CO)2 are proposed.
• The findings necessitate re-evaluation of previous theoretical and experimental interpretations.