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The title compound, bis(dimethyl sulfoxide)triiodo­thallium(III), [TlI3(C2H6OS)2], was crystallized from equimolar amounts of TlII and I2 in a dimethyl sulfoxide (DMSO) solution. After the initial redox reaction, the thallium(III)-iodo complex forms and precipitates as a DMSO solvate. In the crystal structure, Tl is surrounded by three iodide ligands in the equatorial plane and two O-coordinated DMSO mol­ecules in the axial positions, forming a slightly distorted trigonal bipyramid. The complex lies on a twofold rotation axis, making the DMSO mol­ecules and two of the I atoms crystallographically equivalent.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270101020649/bj1035sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270101020649/bj1035Isup2.hkl
Contains datablock I

CCDC reference: 182981

Comment top

The formation of TlIII halide complexes has been studied extensively both in solution and in the solid state (Lee, 1971). Most of these studies dealt with tetrahalo complexes, which can easily be obtained from solutions of thallium and an excess of halide. The thallium(III) tetraiodide anion has usually been prepared using large monovalent cations such as quaternary ammonium and arsonium ions, e.g. in (C6H5)3AsTlI4 and [N(C4H9)4]TlI4, providing the first evidence that the [TlI4]- complex formed in the presence of TlIII and I- (Cotton et al., 1965). Considering crystal structure studies of thallium(III) iodide complexes, only the structures of the tetraiodo anion (TlI4-) with organic cations [N(C4H9)4]+ and [C5H5NH]+ have been determined (Glaser et al., 1982; Drew & Lewis, 1970). In both cases, the TlI4- entity is a distorted tetrahedron with Tl—I distances in the range 2.760–2.797 Å and angles between 106.0 and 112.7°.

The first preparation of thallium triiodide dates from 1864 (Lee, 1971) and its properties have stimulated much interest. In the subsequent development of thallium iodide chemistry, several complexes with the formula TlX3L2, such as TlI3(OPPh3)2, have been prepared. Elemental analysis as well as vibrational spectroscopy indicated compositions and structures consistent with a trigonal bipyramidal species (Bermejo & Gayoso, 1985). The crystal structure determination of the mixed halide TlBrI2(OPPh3)2 confirmed the trigonal bipyramidal structure of the complex.

Hitherto, there has been no structural characterization of a TlI3 species and the X-ray structure determination of yellow-red crystals obtained from a DMSO solution containing TlI/I2 in a 1:1 molar ratio was undertaken to fill this gap. Selected geometric parameters are given in Table 1, an ORTEP plot of the structure is given in Fig.1. The molecule forms a trigonal bipyramid with the three I atoms residing in the trigonal plane. The molecule sits astride a crystallographic twofold axis, which passes through the Tl and I2 positions. The trigonal bipyramid is slightly distorted and superficially resembles the molecular structures of TlX3·3H2O (X=Cl, Br) (Glaser, 1979) and TlBrI2 (Castineiras, 1986). In TlI3(DMSO)2 the Tl atom resides in the equatorial plane whereas for the trichloro and tribromo derivatives the Tl atom is out of the plane by 0.071 (1) and 0.101 (1) Å for the chloro and bromo derivatives, respectively. TlI3(DMSO)2 is similar to TlI2Br(OPPh3)2 in that the TlIII is located in the plane of the halides. For the title complex, the Tl—O distance is 2.469 (6) Å. The mean Tl—I distance is 2.709 (1) Å which is slightly longer than in TlI2Br(OPPh3)2 [Tl—I=2.676 (1) Å]. The three I—Tl—I angles are closer to 120° than those in TlX3·4H2O (X=Cl, Br) and TlI2Br(OPPh3)2. A larger deviation of this angle from 120° in TlI2Br(OPPh3)2 is to be expected due to the different ionic radii of I and Br ions in the TlIII coordination sphere. The O—Tl—O angle in all the four crystal structures deviates slightly from 180°.

For DMSO as a solvating ligand bonded to TlIII, only one complex has been reported in the literature, [TlCl5(DMSO)](Hpyr)2 (James et al., 1983). Here, the Tl—O distance is 2.42 Å which is shorter than in the title complex [?2.469 (6)?Å]. Very recently, the structure of the TlIII–DMSO complex [Tl(DMSO)6](ClO4)3 was determined in this laboratory and the Tl—O bond distance was found to be 2.224 (3) Å (Ma et al., 2002). Thus, the Tl—O distance in the TlIII–halide–DMSO complexes is much longer ?2.469 (6)?Å than that in the Tl-DMSO perchlorate, which is certainly caused by the strong Tl—halide bonds. The mean Tl—I distance of 2.709 (1) Å in [TlI3(DMSO)2] is shorter than that in TlI4- [2.764 (4) Å]. This is in part due to the large ionic radius of the iodide ion but also to the fact that the number of strongly coordinated ligands increases from TlI3 to TlI4- (the Tl—O bond is weak, see above). The common oxidation states of thallium are TlI and TlIII. The oxidation potential for Tl3+/Tl+ is 1.25 V, that for I3-/I- is 0.53 V (Lee, 1971), which means that TlIII should not be stable in the presence of iodide. However, the studied compound clearly shows that the complex TlI3 exists and contains both TlIII and I-. This is certainly due to the stabilizing effect of the strong bond between the soft ions Tl3+ and I-. This effect is also present in pyridine solution where the formation of extremely strong complexes with the composition TlIn3-n has been observed by means of 205Tl NMR spectroscopy (unpublished results from this laboratory).

Experimental top

The title compound was synthesized by mixing equimolar amounts of thallium(I) iodide and iodine in DMSO solution. The yellow-red plate-shaped crystals were crystallized from a red-brown 0.1M TlI3solution (1:1 TlI/I2) in a closed flask over a month. The Raman spectrum of the crystals was recorded using a Renishaw system 1000 spectrometer, equipped with a Leica DMLM microscope. The band positions and assignments are: 2905m (CH3-str.); 1402w, 987w and 936w (CH3-bend); 707m and 672 s (CS-str.); 405m (Tl—O str.), 322w and 301m (OSC-bend); 161vs and 123.4vs (Tl—I str.). (The abbreviations are versus very strong, s strong, m medium and w weak.)

Refinement top

The data set showed the monoclinic symmetry, the reflection condition hkl: h+k=2n indicated a C-centered lattice. Additionally, a zonal extinction h0l: l=2n was observed. Of the two possible space groups, Cc and C2/c, the latter centrosymmetric one was confirmed in the course of the structure determination and refinement.

Computing details top

Data collection: maXus (Mackay et al., 1999); cell refinement: maXus (Mackay et al., 1999); data reduction: DENZO and Scalepak (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Bergerhoff, 1996) and maXus?; software used to prepare material for publication: maXus (Mackay et al., 1999)??.

Figures top
[Figure 1] Fig. 1. ORTEP view of the complex [TlI3(DMSO)2]. The thermal displacement ellipsoids represent a 70% probability level, hydrogen atoms held to arbitrary radii.
(I) top
Crystal data top
[TlI3{(CH3)2SO}2]Dx = 3.008 Mg m3
Mr = 741.34Mo Kα radiation, λ = 0.71073 Å
Monoclinic, C2/cCell parameters from 10534 reflections
a = 8.8785 (3) Åθ = 2.9–27.5°
b = 14.9833 (6) ŵ = 15.76 mm1
c = 12.5835 (5) ÅT = 298 K
β = 102.065 (2)°Cube, yellow red
V = 1637.00 (10) Å30.30 × 0.27 × 0.20 mm
Z = 4
Data collection top
Nonius KappaCCD
diffractometer
1715 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.065
ϕ scansθmax = 27.4°
Absorption correction: integration
HABITUS (Herrendorf & Baernighausen, 1993)
h = 911
Tmin = 0.039, Tmax = 0.265k = 1819
7155 measured reflectionsl = 1516
1842 independent reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.041 w = 1/[σ2(Fo2) + (0.0422P)2 + 14.8122P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.105(Δ/σ)max < 0.001
S = 1.09Δρmax = 1.62 e Å3
1842 reflectionsΔρmin = 1.87 e Å3
59 parametersExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.0017 (2)
Primary atom site location: structure-invariant direct methods
Crystal data top
[TlI3{(CH3)2SO}2]V = 1637.00 (10) Å3
Mr = 741.34Z = 4
Monoclinic, C2/cMo Kα radiation
a = 8.8785 (3) ŵ = 15.76 mm1
b = 14.9833 (6) ÅT = 298 K
c = 12.5835 (5) Å0.30 × 0.27 × 0.20 mm
β = 102.065 (2)°
Data collection top
Nonius KappaCCD
diffractometer
1842 independent reflections
Absorption correction: integration
HABITUS (Herrendorf & Baernighausen, 1993)
1715 reflections with I > 2σ(I)
Tmin = 0.039, Tmax = 0.265Rint = 0.065
7155 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0410 restraints
wR(F2) = 0.105H-atom parameters constrained
S = 1.09 w = 1/[σ2(Fo2) + (0.0422P)2 + 14.8122P]
where P = (Fo2 + 2Fc2)/3
1842 reflectionsΔρmax = 1.62 e Å3
59 parametersΔρmin = 1.87 e Å3
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Tl10.50000.28189 (3)0.25000.0517 (2)
I10.24771 (9)0.37076 (7)0.14114 (8)0.1000 (3)
I20.50000.10224 (6)0.25000.1013 (5)
S10.3785 (3)0.38279 (16)0.46274 (19)0.0653 (5)
O10.3878 (9)0.2908 (4)0.4134 (5)0.0684 (17)
C10.4407 (18)0.3661 (11)0.6046 (10)0.103 (5)
C20.1803 (14)0.3981 (8)0.4629 (9)0.078 (3)
H1A0.548 (9)0.3566 (14)0.6212 (18)0.123*
H1B0.390 (4)0.316 (4)0.626 (2)0.123*
H1C0.417 (3)0.417 (4)0.642 (3)0.123*
H2A0.123 (4)0.4085 (10)0.388 (5)0.094*
H2B0.1679 (17)0.450 (4)0.509 (3)0.094*
H2C0.140 (3)0.344 (4)0.493 (2)0.094*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Tl10.0610 (3)0.0359 (2)0.0598 (3)0.0000.01587 (18)0.000
I10.0709 (5)0.1111 (7)0.1151 (6)0.0225 (4)0.0127 (4)0.0445 (5)
I20.1841 (14)0.0346 (4)0.0977 (7)0.0000.0579 (8)0.000
S10.0823 (14)0.0478 (11)0.0709 (12)0.0016 (10)0.0279 (11)0.0038 (9)
O10.097 (5)0.047 (3)0.068 (4)0.000 (3)0.034 (3)0.000 (3)
C10.125 (11)0.099 (10)0.076 (7)0.017 (9)0.003 (7)0.017 (6)
C20.090 (7)0.061 (6)0.089 (7)0.009 (5)0.030 (5)0.001 (5)
Geometric parameters (Å, º) top
Tl1—O12.469 (6)S1—C11.772 (13)
Tl1—I22.6916 (10)S1—C21.775 (12)
Tl1—I12.7173 (7)C1—H1A0.9408
S1—O11.521 (7)C2—H2A0.9921
O1i—Tl1—O1173.8 (3)S1—C1—H1B109.5
O1—Tl1—I293.09 (15)H1A—C1—H1B109.5
O1—Tl1—I1i89.26 (18)S1—C1—H1C109.5
O1—Tl1—I187.71 (18)H1A—C1—H1C109.5
I2—Tl1—I1119.34 (3)H1B—C1—H1C109.5
I1i—Tl1—I1121.31 (5)S1—C2—H2A109.5
O1—S1—C1104.5 (6)S1—C2—H2B109.5
O1—S1—C2104.8 (5)H2A—C2—H2B109.5
C1—S1—C296.7 (6)S1—C2—H2C109.5
S1—O1—Tl1117.0 (4)H2A—C2—H2C109.5
S1—C1—H1A109.5H2B—C2—H2C109.5
Symmetry code: (i) x+1, y, z+1/2.

Experimental details

Crystal data
Chemical formula[TlI3{(CH3)2SO}2]
Mr741.34
Crystal system, space groupMonoclinic, C2/c
Temperature (K)298
a, b, c (Å)8.8785 (3), 14.9833 (6), 12.5835 (5)
β (°) 102.065 (2)
V3)1637.00 (10)
Z4
Radiation typeMo Kα
µ (mm1)15.76
Crystal size (mm)0.30 × 0.27 × 0.20
Data collection
DiffractometerNonius KappaCCD
diffractometer
Absorption correctionIntegration
HABITUS (Herrendorf & Baernighausen, 1993)
Tmin, Tmax0.039, 0.265
No. of measured, independent and
observed [I > 2σ(I)] reflections
7155, 1842, 1715
Rint0.065
(sin θ/λ)max1)0.648
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.041, 0.105, 1.09
No. of reflections1842
No. of parameters59
H-atom treatmentH-atom parameters constrained
w = 1/[σ2(Fo2) + (0.0422P)2 + 14.8122P]
where P = (Fo2 + 2Fc2)/3
Δρmax, Δρmin (e Å3)1.62, 1.87

Computer programs: , DENZO and Scalepak (Otwinowski & Minor, 1997), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), DIAMOND (Bergerhoff, 1996) and maXus?, maXus (Mackay et al., 1999)??.

Selected geometric parameters (Å, º) top
Tl1—O12.469 (6)S1—O11.521 (7)
Tl1—I22.6916 (10)S1—C11.772 (13)
Tl1—I12.7173 (7)S1—C21.775 (12)
O1i—Tl1—O1173.8 (3)I1i—Tl1—I1121.31 (5)
O1—Tl1—I293.09 (15)O1—S1—C1104.5 (6)
O1—Tl1—I1i89.26 (18)O1—S1—C2104.8 (5)
O1—Tl1—I187.71 (18)C1—S1—C296.7 (6)
I2—Tl1—I1119.34 (3)
Symmetry code: (i) x+1, y, z+1/2.
 

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