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Trans or (Unusual) Cis Geometry in d(2) Octahedral Dioxo Complexes. A DFT Study.
1Laboratoire de Chimie Théorique (URA 506), Bâtiment 490, Université de Paris-Sud, 91405 Orsay Cedex, France.
Inorganic Chemistry
|August 14, 1996
Summary
Computational chemistry reveals that chelating ligands can invert the stability of cis and trans dioxo metal complexes. This finding is crucial for understanding the geometry and reactivity of these important inorganic compounds.
Area of Science:
- Inorganic Chemistry
- Computational Chemistry
- Quantum Chemistry
Background:
- Octahedral dioxo complexes with d(2) electronic configuration are common in inorganic chemistry.
- The relative stability of cis and trans isomers is typically governed by ligand properties.
- Previous studies often assume trans isomers are more stable due to steric and electronic factors.
Purpose of the Study:
- To investigate the geometry optimization of cis and trans isomers of d(2) octahedral dioxo complexes.
- To explore the influence of chelating bidentate ligands on isomer stability.
- To understand the electronic and geometric factors dictating cis/trans isomer preference.
Main Methods:
- Geometry optimization using gradient-corrected density functional theory (DFT).
- Specific functionals employed include B3LYP and BP86.
- Analysis of electronic structure and geometric parameters of model complexes.
Main Results:
- For monodentate ligands, the trans isomer is confirmed as the most stable.
- Chelating ligands induce an inversion of stability: the cis isomer becomes favored in complex 11 (29 kcal mol(-1)).
- Ligand properties, such as bite angle and pi-acceptor ability, are identified as key factors.
Conclusions:
- Chelating bidentate ligands can significantly alter the energetic landscape of dioxo metal complexes.
- The pi-acceptor character and bite angle of chelating ligands are critical for cis isomer stabilization.
- These findings provide insights into the synthesis and reactivity of specific inorganic complexes.