Structure and bonding of bisaquamercury(II) and trisaquathallium(III) trifluoromethanesulfonate

Alireza Molla-Abbassi, Lars Eriksson, János Mink, Ingmar Persson, Magnus Sandström, Mikhail Skripkin, Ann Sofi Ullström, Patric Lindqvist-Reis

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The structure and bonding in bisaquamercury(II) trifluoromethanesulfonate, [Hg(OH2)2(CF3SO3)2] , and trisaquathallium(III) trifluoromethanesulfonate, [Tl(OH2)3(CF3SO3)3], have been studied by means of single-crystal X-ray diffraction, EXAFS and vibrational spectroscopy. The crystal structure of bisaquamercury(II) trifluoromethanesulfonate shows an unusual connectivity pattern. The mercury(II) ion strongly binds two water molecules axially with the Hg-O bond distance 2.11 Å, and four oxygen atoms from four trifluoromethanesulfonate ions complete a tetragonally compressed octahedral coordination geometry, at the mean Hg-O distance 2.53 Å. Two trifluoromethanesulfonate ions form double bridges between the bisaquamercury(II) entities giving rise to infinite >Hg(OH2)2 <(CF3SO3)2 >Hg(OH2)2< chains. The parallel chains are held together in layers by relatively strong hydrogen bonds with O(-H)···O distances in the range 2.688(9)-2.735(9) Å. The O-D stretching vibrational frequencies of the hydrogen bonds in the partly deuterated compound occur in a broad band at about 2400 cm-1, bandwidth ca. 170 cm-1. The layers are connected onlyvia van der Waals interactions between the protruding CF3 groups, consistent with the fragile sheet-like structure of the crystalline compound. Trisaquathallium(III) trifluoromethanesulfonate crystallises as molecular complexes where each thallium(III) ion binds three water molecules and three oxygen atoms from trifluoromethanesulfonate ions, with Tl-O bond distances in the range 2.18-2.24 Å. A hydrogen bond network between the water molecules and trifluoromethanesulfonate ions with O(-H)···O distances in the range 2.65(1)-2.80(1) Å holds the structure together. Raman and infrared spectra have been recorded and analysed. The changes in force constants and vibrational frequencies have been correlated with bond lengths for the S-O bond in the coordinated trifluoromethanesulfonate ion and for the Hg-O and Tl-O bonds, also including the hexaaquaions in the comparisons.

Original languageEnglish
Pages (from-to)4357-4364
Number of pages8
JournalJournal of the Chemical Society, Dalton Transactions
Issue number23
Publication statusPublished - Dec 1 2002


ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Molla-Abbassi, A., Eriksson, L., Mink, J., Persson, I., Sandström, M., Skripkin, M., Ullström, A. S., & Lindqvist-Reis, P. (2002). Structure and bonding of bisaquamercury(II) and trisaquathallium(III) trifluoromethanesulfonate. Journal of the Chemical Society, Dalton Transactions, (23), 4357-4364.