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Synthesis and Characterization of Functionalized Metal-organic Frameworks
Published on: September 5, 2014
Structure and bonding in [M(6)O(19)](n-) isopolyanions
Adam J Bridgeman1, Germán Cavigliasso
1Departments of Chemistry, University of Hull, Kingston upon Hull, HU6 7RX, UK. A.J.Bridgeman@hull.ac.uk
Inorganic Chemistry
|April 2, 2002
Summary
Density-functional methods reveal M-O bonding in isopolyanions of Nb, Ta, Mo, and W. Metal-oxygen interactions are primarily M d-O p, influencing molecular stability and charge distribution.
Area of Science:
- Inorganic Chemistry
- Computational Chemistry
- Materials Science
Background:
- Isopolyanions, particularly those of early transition metals like Nb, Ta, Mo, and W, are crucial in various chemical processes.
- Understanding their structure and bonding is key to predicting their reactivity and properties.
Purpose of the Study:
- To investigate the structure and bonding of [M(6)O(19)](n-) isopolyanions for Nb, Ta, Mo, and W.
- To analyze the electronic structure and bonding characteristics using various computational methods.
Main Methods:
- Density-functional theory (DFT) calculations were employed.
- Molecular-orbital, Mulliken-Mayer, and bonding-energy analyses were performed.
- Computational-experimental agreement was assessed for geometrical parameters.
Main Results:
- Good agreement between computational and experimental geometries for Mo and W species; less so for Nb and Ta.
- M-O interactions are predominantly M d-O p, with sigma and pi bonding contributions.
- Mayer bond indexes indicate varying bond orders for terminal, bridging, and internal oxygen atoms.
- Mulliken analysis shows charge distribution across oxygen sites and reduced metal charges compared to formal oxidation states.
- Minimal structural changes observed upon reduction of molybdates and tungstates.
Conclusions:
- The electronic structure and bonding in these isopolyanions are well-described by DFT.
- The M-O bonding is a complex interplay of sigma and pi interactions, with charge delocalization.
- The findings provide insights into the stability and electronic properties of early transition metal isopolyanions.
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