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.

The structure and vibrational spectra of the dimethyl sulfoxide solvated thallium(III) ion have been studied in a dimethyl sulfoxide solution and in the solid state. X-ray crystallography shows a trigonal unit cell, space group R(-)3 (No. 148), for the [Tl(dmso)(6)](ClO(4))(3) compound with Z = 3, a = b = 11.9764(13) [11.8995(9)] A, c = 20.802(2) [20.467(2)] A, and V = 2584.0(5) [2509.9(4)] A(3) at 295 [150] K. The crystal structure comprises a highly symmetric hexakis(dimethyl sulfoxide)thallium(III) ion, with thallium in a (-)3 symmetry site and a Tl-O bond distance of 2.224(3) A at 295 K. The octahedral TlO(6) kernel is compressed along the threefold axis with an O-Tl-O bond angle of 96.20(11) degrees. The Tl-O-S bond angle of 120.7(2) degrees corresponds to a Tl.S distance of 3.292(2) A. One perchlorate ion centered on the (-)3 axis was described by a statistically disordered model. A low-temperature EXAFS study (10 K) resulted in the Tl-O and Tl.S distances of 2.221(4) and 3.282(6) A, respectively, consistent with a Tl-O-S bond angle of 120(1) degrees. The low Debye-Waller factors confirm a regular coordination without the disorder of the dimethyl sulfoxide ligands, which would have resulted from the alternative choice of space group R3 for the crystal structure. Raman and infrared spectra have been recorded and assigned, with the bands at 435 and 447 cm(-)(1) corresponding to the vibrational frequency of the symmetric and asymmetric Tl-O stretching modes, respectively. EXAFS data of a 0.5 mol dm(-3)thallium(III) trifluoromethanesulfonate in a dimethyl sulfoxide solution were consistent with that of a hexasolvated ion with mean Tl-O and Tl.S distances of 2.22(1) and 3.33(2) A, respectively, which correspond to a mean Tl-O-S bond angle of 124(2) degrees. The anomalously large disorder parameter for the Tl-O distances is consistent with a weak pseudo-Jahn-Teller effect. The (205)Tl, (13)C, and (1)H NMR spectra of the complex in solution show single signals at 1886, 39.5, and 2.3 ppm, respectively.

The isostructural hexakis(dimethyl sulfoxide)-aluminium(), -gallium() and -indium() iodides crystallise in the trigonal space group R3 (no. 148), Z = 3, at 295 ± 1 K. The metal ions are located in a 3 symmetry site with M-O bond distances of 1.894(4), 1.974(4) and 2.145(3) Å, and M-O-S bond angles of 127.1(3), 124.1(3) and 123.1(2)Њ, for M = Al, Ga and In, respectively. The unit cell parameters are a = 10.762(2), c = 24The increasing compression of the octahedral MO 6 coordination entities along one three-fold axis for M = Al, Ga and In, respectively, explains why the largest ion indium() has the smallest unit cell volume. EXAFS measurements on the dimethyl sulfoxide solvated gallium() and indium() ions in solution and in the solid perchlorate and trifluoromethanesulfonate salts, show similar bond distances as in the solid iodide solvates. Raman and infrared spectra have been recorded for the hexakis(dimethyl sulfoxide)metal() iodides and the nature of the metal-sulfoxide bond has been evaluated by normal coordinate methods.