Hard Acid and Soft Base Stabilisation of Di- and Trimercury Cations in Benzene Solution – A Spectroscopic, X-ray Scattering, and Quantum Chemical Study
✍ Scribed by Stefan Ulvenlund; Jan Rosdahl; Andreas Fischer; Peter Schwerdtfeger; Lars Kloo
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 340 KB
- Volume
- 1999
- Category
- Article
- ISSN
- 1434-1948
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✦ Synopsis
Hg 2 Cl 2 dissolves in GaCl 3 /benzene solution to yield Hg 2 2+ for such specific interactions between Hg m 2+ cations and C 6 H 6 are observed in the Raman spectra: The totally and chlorogallate(III) ions, Ga n Cl 3n+1 -. In such solutions, Hg 2 2+ can be reduced to Hg 3 2+ by metallic mercury. symmetric C 6 H 6 band at 991 cm -1 is found to split in the presence of Hg m 2+ ions and to give new peaks at 978 (m = 2) Solubility measurements show that one mol of Hg is oxidised per mol of Hg 2 2+ . The Hg 3 2+ ion gives a strong band at 110 and 982 (m = 3) cm -1 . -In order to further elucidate the cluster-arene interactions, ab initio and density functional cm -1 in the Raman spectrum and Hg-Hg correlations at about 2.60 and 5.15 A ˚in the radial distribution function calculations were performed for the model compounds Hg m (C 6 H 6 ) 2 2+ and Hg m Cl 2 (C 6 H 6 ) 2 , m = 2 and 3. The obtained by liquid X-ray scattering. -Hg 3 2+ can also be synthesised in high yield by direct oxidation of metallic calculations show that both models represent coordinations modes which are feasible for Hg m 2+ ions. However, the mercury by Ga III in GaCl 3 /benzene solution. In contrast, mercury is insoluble in neat liquid GaCl 3 and only sparingly calculated vibrational frequencies for the Hg m (C 6 H 6 ) 2 2+
models with η 1 /quasi-η 3 coordination of the benzene soluble in GaCl 3 /KCl melts. It therefore seems likely that the thermodynamic stabilisation of subvalent mercury species in molecules along the Hg-Hg vector are most consistent with the body of experimental and literature data. The benzene solution not only relies on the traditional acid stabilisation provided by the hard Lewis acid GaCl 3 , but also counterions are thus suggested to occupy secondary coordination sites. on a "soft-base stabilisation" provided by interactions between the aromatic molecules and the cations. Evidence
As is the case with the vast majority of subvalent posthave, of course, a pronounced soft character. Considering P. O. Box 34, S-22100 Lund, Sweden [b] Inorganic Chemistry, Royal Institute of Chemistry, the recent success of stabilising subvalent mercury species S-10044 Stockholm, Sweden in systems comprising other soft donors (i.e. diphosphanes),