Structure and bonding of bisaquamercury(ii) and trisaquathallium(iii) trifluoromethanesulfonate

Abstract

The structure and bonding in bisaquamercury() trifluoromethanesulfonate, [Hg(OH 2 ) 2 (CF 3 SO 3 ) 2 ] ∞ , and trisaquathallium() trifluoromethanesulfonate, [Tl(OH 2 ) 3 (CF 3 SO 3 ) 3 ], have been studied by means of single-crystal X-ray diffraction, EXAFS and vibrational spectroscopy. The crystal structure of bisaquamercury() trifluoromethanesulfonate shows an unusual connectivity pattern. The mercury() 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() entities giving rise to infinite >Hg(OH 2 ) 2 <(CF 3 SO 3 ) 2 >Hg(OH 2 ) 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 Ϫ1 , bandwidth ca. 170 cm Ϫ1 . The layers are connected only via van der Waals interactions between the protruding CF 3 groups, consistent with the fragile sheet-like structure of the crystalline compound. Trisaquathallium() trifluoromethanesulfonate crystallises as molecular complexes where each thallium() 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.

Vibrational spectroscopic force field studies of dimethyl sulfoxide and hexakis(dimethyl sulfoxide)scandium(iii) iodide, and crystal and solution structure of the hexakis(dimethyl sulfoxide)scandium(iii) ion

“…1) and iodide ions. The scandium ion in a site of3 symmetry is octahedrally surrounded by six oxygen atoms with the Sc-O bond distance 2.069(3) Å and the O-Sc-O angle 92.00 (15) • in the [Sc(OSMe 2 ) 6 ] 3+ complex. The S-O distance of the dimethyl sulfoxide ligands is 1.536(4) Å , and the Sc-O-S angle 132.6(2)…”

“…However, we do not obtain a strict correlation between the S-O or M-O bond distances and the S-O force constants. 15 For the aluminium and scandium complexes the S-O stretching force constants are significantly higher than expected, probably because these d 0 ions lack back-bonding possibility. For the d 10 ions, gallium(III), indium(III) and thallium(III), back-bonding can increase the M-O bond strength, which then causes a weakening of the S-O bond.…”

“…148). 15 The crystal structure comprises discrete hexakis(dimethyl sulfoxide)scandium(III) complexes (Fig. 1) and iodide ions.…”

“…29 Therefore, in the current work, as also for aluminium(III), gallium(III), indium(III), 15 and other trivalent metal ions, 17,18 the "soft" anion iodide was chosen for the crystallographic studies as it forms weak complexes with "hard" ions, 29 and does not give rise to additional bands in the vibrational spectra. EXAFS spectroscopy was used to study the structure of the solvated scandium(III) ion in dimethyl sulfoxide solution.…”

Ambidentate coordination in hydrogen bonded dimethyl sulfoxide, (CH3)2SO⋯H3O+, and in dichlorobis(dimethyl sulfoxide) palladium(ii) and platinum(ii) solid solvates, by vibrational and sulfur K-edge X-ray absorption spectroscopy

“…In the present work normal coordinate force field analyses of the solid state vibrational spectra were performed for the trans-PdCl 2 ((CH 3 ) 2 SO) 2 and cis-PtCl 2 ((CH 3 ) 2 SO) 2 complexes to enable comparisons of the character of the metal-sulfur and metal-chloride bonding in square planar coordination. The results are combined with sulfur K-edge XANES measurements, which when evaluated by DFT-TP calculations provide information about the electronic state of the investigated compounds.…”