Comparison between post-Hartree-Fock and DFT methods for the study of strength and mechanism of cleavage of Hg(SINGLE BOND)C bond
✍ Scribed by Vincenzo Barone; Alessandro Bencini; Federico Totti; Myriam G. Uytterhoeven
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 147 KB
- Volume
- 61
- Category
- Article
- ISSN
- 0020-7608
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✦ Synopsis
A parallel MP2 and DFT study was performed for mercury dihalides and for representative organomercury compounds including a HgᎏC bond. From a methodological point of view, medium-size basis sets provide reliable general trends for a number of properties already at the HF level. However, quantitative results can only be Ž . obtained including correlation energy by post-Hartree᎐Fock even at the MP2 level or density functional models and adding f-polarization functions on Hg. At this level, geometrical parameters are sufficiently accurate for most purposes and reliable thermodynamic data can be obtained using isodesmic reactions. The advantage of the DF approach resides, besides the shorter computation times, in the lower dependence of the results on the basis set. From a more general point of view, all the computations indicate that HgᎏC bond breaking is favored, decreasing the electronegativity of further substituents. We have next investigated the reaction mechanism for cleavage of the HgᎏC bond by halogenic acids. Our results show that the reaction occurs through a one-step mechanism in which, however, bond forming and breaking are not completely synchronous.