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Research article - Peer-reviewed, 2002

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

Molla-Abbassi, A; Eriksson, L; Mink, J; Persson, M; Sandstrom, M; Skripkin, M; Ullstrom, AS; Lindqvist-Reis, P


The structure and bonding in bisaquamercury(II) trifluoromethanesulfonate, [Hg(OH2)(2)(CF3SO3)(2)](infinity), 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) trifluoromethane sulfonate shows an unusual connectivity pattern. The mercury(II) ion strongly binds two water molecules axially with the Hg-O bond distance 2.11 Angstrom, and four oxygen atoms from four trifluoromethanesulfonate ions complete a tetragonally compressed octahedral coordination geometry, at the mean Hg-O distance 2.53 Angstrom. 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) ∠S;. The O-D stretching vibrational frequencies of the hydrogen bonds in the partly denterated compound occur in a broad band at about 2400 cm(-1), bandwidth ca. 170 cm(-1). The layers are connected only via 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(m) ion binds three water molecules and three oxygen atoms from trifluoromethanesulfonate ions, with T1-O bond distances in the range 2.18-2.24 ∠S;. 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) ∠S; 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 T1-O bonds, also including the hexaaquaions in the comparisons.

Published in

Journal Of The Chemical Society-Dalton Transactions
2002, number: 23, pages: 4357-4364

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        Physical Chemistry
        Inorganic Chemistry

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