Theoretical calculations on the structure of the hexahydrated divalent zinc, cadmium and mercury ions

✍ Scribed by Dan Strömberg; Magnus Sandström; Ulf Wahlgren

• Publisher: Elsevier Science
• Year: 1990
• Tongue: English
• Weight: 573 KB
• Volume: 172
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(90)87215-d

✦ Synopsis

SCF calculations have been performed on the title compounds in order to study the possible reasons for the anomalously large spread in the mean Hg-0 bond distance previously obtained for hydrated mercury (II) ions in solution. An energy minimum is found for all three complexes, [M ( HsO), ] 2+, M=Zn, Cd or Hg, for a regular Tb ground-state nuclear configuration. The larger spread of the Hg-0 distances can bc explained in terms of a weak second-order Jahn-Teller effect. An enhanced vibronic coupling leads in the mercury case to larger vibrational amplitudes of the coupling mode without invoking a static distortion. The longer mean Hg-0 distance found for the hydrated mercury (II) ion in solution than in a solid hexahydratc can be explained by assuming a larger asymmetry in the distribution of the Hg-0 bonds. Calculations on the [ Hg(HsS)s] '+ complex also show an energy minimum for the Ta configuration, although in this case the adiabatic potential surface is vcty tlat, and more refined methods of calculation could yield a distorted ground-state confguration.