Structure of the dimethyl sulfoxide solvated thallium(III) ion in solutionand in the solid state

The structure and vibrational spectra of the dimethyl sulfoxide solvated th allium(III) ion have been studied in a dimethyl sulfoxide solution and in t he solid state. X-ray crystallography shows a trigonal unit cell, space gro up R (3) over bar (No. 148), for the [TI(dmso)(6)](ClO4)(3) Compound with Z = 3, a = b = 11.9764(13) [11.8995(9)] Angstrom, c = 20.802(2) [20.467(2)] Angstrom, and V = 2584.0(5) [2509.9(4)] Angstrom (3) at 295 [150] K. The cr ystal structure comprises a highly symmetric hexakis(dimethyl sulfoxide)tha llium(III) ion, with thallium in a 3 symmetry site and a TI-O bond distance of 2.224(3) Angstrom at 295 K. The octahedral TlO6 kernel is compressed al ong the threefold axis with an O-Tl-O bond angle of 96.20(11)degrees. The T l-O-S bond angle of 120.7(2)degrees corresponds to a Tl . . .S distance of 3.292(2) Angstrom. One perchlorate ion centered on the (3) over bar axis wa s described by a statistically disordered model. A low-temperature EXAFS st udy (10 K) resulted in the TI-O and Tl . . .S distances of 2.221(4) and 3.2 82(6) Angstrom, respectively, consistent with a Tl-O-S bond angle of 120(1) degrees. The low Debye-Waller factors confirm a regular coordination withou t the disorder of the dimethyl sulfoxide ligands, which would have resulted from the alternative choice of space group R3 for the crystal structure. R aman and infrared spectra have been recorded and assigned, with the bands a t 435 and 447 cm(-1) corresponding to the vibrational frequency of the symm etric and asymmetric TI-O stretching modes, respectively. EXAFS data of a 0 .5 mol dm(-3) thallium(III) trifluoromethanesulfonate in a dimethyl sulfoxi de 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) Angstrom, respectively, whic h correspond to a mean Tl-O-S bond angle of 124(2)degrees. The anomalously large disorder parameter for the TI-O distances is consistent with a weal, pseudo-Jahn-Teller effect. The Tl-205, C-13, and H-1 NMR spectra of the com plex in solution show single signals at 1886, 39.5, and 2.3 ppm, respective ly.