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Determination of the Gas-phase Acidities of Oligopeptides
Published on: June 24, 2013
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Ga(+) Basicity and Affinity Scales Based on High-Level Ab Initio Calculations
Oriana Brea1, Otilia Mó1, Manuel Yáñez2
1Departamento de Química, Módulo 13, Universidad Autónoma de Madrid, Campus de Excelencia UAM-CSIC, Cantoblanco, 28049, Madrid, Spain), Fax.
Summary
This study investigates gallium cation (Ga+) interactions with various compounds using advanced computational methods. Findings reveal a significant covalent character in Ga+ bonding, influencing its cation affinity and basicity scales, and leading to unexpected differences compared to aluminum (Al+).
Area of Science:
- Computational Chemistry
- Quantum Chemistry
- Inorganic Chemistry
Background:
- Understanding metal cation interactions with Lewis bases is crucial in chemistry.
- Gallium cation (Ga+) interactions are less understood compared to other alkali or alkaline earth metal cations.
- Previous studies often focused on electrostatic interactions, potentially overlooking other bonding aspects.
Purpose of the Study:
- To investigate the structure, stability, and bonding of Ga+ complexes with diverse Lewis bases.
- To establish accurate gallium cation affinity (GaCA) and gallium cation basicity (GaCB) scales.
- To compare Ga+ interactions with those of other metal cations like Al+ and Li+.
Main Methods:
- Utilized the high-level composite ab initio Gaussian-4 (G4) theory for calculations.
- Investigated complexes formed by Ga+ with hydrocarbons, aromatic systems, and O-, N-, F-, S-containing Lewis bases.
- Performed bonding analysis to understand the nature of Ga+-base interactions.
Main Results:
- Established accurate GaCA and GaCB scales based on G4 calculations.
- Demonstrated a significant covalent character in Ga+-base bonding, attributed to Ga+'s empty 4p orbital.
- Observed unexpected differences in relative stability between Ga+ and Al+ complexes, particularly with aromatic compounds.
Conclusions:
- The bonding between Ga+ and Lewis bases is a mix of electrostatic and non-negligible covalent interactions.
- The covalent contribution influences GaCA and GaCB scales, differentiating them from Li+ cation affinities.
- Ga+ exhibits unique complexation behavior, especially with π-systems, compared to Al+.
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