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A Study of the Complexation of Mercury(II) with Dicysteinyl Tetrapeptides by Electrospray Ionization Mass Spectrometry
Published on: January 8, 2016
Mercury dications: linear form is more stable than aromatic ring
Tibor Höltzl1, Minh Tho Nguyen, Tamás Veszprémi
1Budapest University of Technology and Economics, Department of Inorganic and Analytical Chemistry, Szent Gellért tér 4., H-1521 Budapest, Hungary.
Physical Chemistry Chemical Physics : PCCP
|January 13, 2010
Summary
Aromatic mercury rings (Hg(4)(2+) and Hg(6)(2+)) were found to be less stable than their non-aromatic linear counterparts. This surprising finding in aromaticity studies was attributed to charge distribution and ring strain effects.
Area of Science:
- Computational Chemistry
- Inorganic Chemistry
- Quantum Chemistry
Background:
- Aromaticity is a key concept in chemical stability.
- Understanding aromaticity in metal clusters is an ongoing challenge.
- Mercury clusters present unique electronic properties.
Purpose of the Study:
- To investigate the aromaticity of Hg(4)(2+) and Hg(6)(2+) clusters.
- To determine the relative stability of aromatic versus non-aromatic mercury species.
- To explain the observed stability trends using theoretical models.
Main Methods:
- Molecular orbital (MO) analysis.
- Nucleus-independent chemical shift (NICS) calculations.
- High-level quantum chemical methods.
- Phenomenological shell model for metal clusters.
Main Results:
- D(4h) and D(6h) symmetric Hg(4)(2+) and Hg(6)(2+) rings exhibit aromatic characteristics.
- Linear forms of these mercury species are significantly more stable (over 100 kJ mol(-1) lower in energy) than the ring forms.
- Charge distribution and ring strain were identified as the primary factors governing the stability difference.
Conclusions:
- Non-aromatic linear mercury clusters are thermodynamically favored over their aromatic ring counterparts.
- The study highlights exceptions to the general rule that aromaticity confers enhanced stability.
- The phenomenological shell model provides a consistent framework for describing the electronic structures.
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