Hidden superlattice in Tl₂(SC₆H₄S) and Tl₂(SeC₆H₄Se) solved from powder X-ray diffraction

The crystal structures of the isostructural title compounds poly[(μ-benzene-1,4-dithiolato)dithallium], Tl₂(SC₆H₄S), and poly[(μ-benzene-1,4-diselenolato)dithallium], Tl₂(SeC₆H₄Se), were solved by simulated annealing from high-resolution synchrotron X-ray powder diffraction. Rietveld refinements of an initial structure with one formula unit per triclinic cell gave satisfactory agreement with the data, but led to a structure with impossibly close non-bonded contacts. A disordered model was proposed to alleviate this problem, but an alternative supercell structure leads to slightly improved agreement with the data. The isostructural superlattice structures were confirmed for both compounds through additional data collection, with substantially better counting statistics, which revealed the presence of very weak superlattice peaks not previously seen. Overall, each structure contains Tl—S or Tl—Se two-dimensional networks, connected by phenylene bridges. The sulfur (or selenium) coordination sphere around each thallium is a highly distorted square pyramid or a `see-saw' shape, depending upon how many Tl—S or Tl—Se interactions are considered to be bonds. In addition, the two compounds contain pairs of Tl<sup>I</sup> ions that interact through a closed-shell `thallophilic' interaction: in the sulfur compound there are two inequivalent pairs of Tl atoms with Tl—Tl distances of 3.49 and 3.58 Å, while in the selenium compound those Tl—Tl interactions are at 3.54 and 3.63 Å.

Computing details

For both compounds, data collection: spec; cell refinement: TOPAS-Academic (Coelho, 2007); data reduction: X16C beamline software; program(s) used to solve structure: TOPAS-Academic (Coelho, 2007); program(s) used to refine structure: TOPAS-Academic (Coelho, 2007); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and Mercury (Version 2.2; Macrae et al., 2006); software used to prepare material for publication: publCIF (Westrip, 2009).

Figures

(Tl2SC6H4S)

Crystal data

Tl2·(SC6H2S)	V = 404.85 (9) Å^3
Mr = 549.0	Z = 4
Triclinic, P1	Synchrotron radiation, λ = 0.698163 Å
Hall symbol: P-1	µ = 37 mm^−1
a = 6.5525 (3) Å	T = 298 K
b = 6.8444 (3) Å	Particle morphology: fine powder
c = 9.5265 (2) Å	yellow
α = 71.798 (2)°	cylinder, 8 × 0.7 mm
β = 85.988 (2)°	Specimen preparation: Prepared at 298 K and 101.325 kPa, cooled at 0 K min^−1
γ = 89.219 (2)°

Data collection

Huber diffractometer	Data collection mode: transmission
Radiation source: synchrotron, NSLS Beamline X16C	Scan method: step
Si (111) monochromator	2θmin = 2°, 2θmax = 30°, 2θstep = 0.005°
Specimen mounting: Sample was mounted in a thin walled glass capillary of nominal diameter 0.7 mm.

Refinement

Rp = 0.070	57 parameters
Rwp = 0.080	0 restraints
Rexp = 0.065	H-atom parameters not refined
RBragg = 0.019	Weighting scheme based on measured s.u.'s
χ^2 = 1.484	(Δ/σ)max = 0.0001
5601 data points	Background function: Chebyshev polynomial with 8 coeffecients plus 1/(2theta) term
Excluded region(s): none	Preferred orientation correction: none
Profile function: Simple_Axial_Model(width parameter 8.80/300) function with Rp=9999,Rs=300 in TOPAS-Academic

Special details

Experimental. In order to decrease sample absorption, the sample was mixed with finely ground cork before loading into the capillary. This diluted the sample to prevent absorption corrections as well as ensuring no preferred orientation.

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All suś are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

Refinement. The two S(C6H4)S moieties were refined as z-matrices, with planar regula hexagonal symmetry imposed for the aromatic rings, located at inversion centers. S-C bond lengths were refined, but S atoms were fixed in the planes of the hexagons, with S-C—C bond angles fixed at 60 °.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Tl2	0.0132 (4)	0.6150 (6)	0.6442 (4)	0.0385 (7)*
S1	0.05050	0.06291	−0.34303	0.006 (3)*
C1	0.02217	0.02761	−0.15058	0.006 (3)*
C2	−0.11884	0.14282	−0.09585	0.006 (3)*
C3	−0.14101	0.11521	0.05473	0.006 (3)*
Tl1	0.4572 (4)	0.8920 (6)	0.3612 (3)	0.0385 (7)*
S1A	0.53129	0.52569	−0.33719	0.006 (3)*
C1A	0.51373	0.51128	−0.14802	0.006 (3)*
C2A	0.35925	0.39595	−0.05277	0.006 (3)*
C3A	0.34552	0.38467	0.09525	0.006 (3)*
H2	−0.21154	0.25423	−0.17062	0.006 (3)*
H3	−0.25100	0.20508	0.09742	0.006 (3)*
H2A	0.24946	0.31479	−0.09393	0.006 (3)*
H3A	0.22501	0.29471	0.16955	0.006 (3)*

Geometric parameters (Å, º)

Tl2—S1^i	3.0752	C2—H2	1.0800
Tl1—S1A^ii	2.9379	C3—H3	1.0800
S1—C1	1.7695	C1A—C2A	1.3845
S1A—C1A	1.7695	C1A—C3A^ii	1.3845
C1—C3^iii	1.3845	C2A—C3A	1.3845
C1—C2	1.3845	C2A—H2A	1.0800
C2—C3	1.3845	C3A—H3A	1.0800
Tl1···S1A^iv	3.9216	S1···Tl2^xii	3.1193
Tl1···S1^i	3.3483	S1···Tl2^xiii	3.7477
Tl1···S1^ii	3.2321	S1A···Tl1^xiii	3.2309
Tl1···C2^i	3.5408	S1A···Tl2^xiii	3.4481
Tl1···C1^i	3.7868	S1A···Tl2^xiv	3.2067
Tl1···C1^ii	3.7908	S1A···S1A^xv	3.2829
Tl1···C3^v	3.7466	S1A···Tl1^iv	3.9216
Tl1···Tl2	3.897 (4)	C1···Tl1^ii	3.7908
Tl1···S1A^vi	3.2309	C1···Tl1^i	3.7868
Tl1···C3A^vii	3.6304	C1A···C2^xvi	3.4091
Tl2···Tl1	3.897 (4)	C1A···Tl2^xiv	3.6622
Tl2···C2^vi	3.4788	C2···C3A^i	3.5418
Tl2···S1^vi	3.7477	C2···C1A^xvii	3.4091
Tl2···C2A^vi	3.7206	C2···Tl1^i	3.5408
Tl2···S1^viii	3.1193	C2···Tl2^xiii	3.4788
Tl2···S1A^ix	3.2067	C2A···Tl2^xiii	3.7206
Tl2···S1A^vi	3.4481	C3···C3A^i	3.5555
Tl2···C1A^ix	3.6622	C3···Tl1^xviii	3.7466
Tl2···C3A^x	3.2974	C3A···Tl2^x	3.2974
S1···S1^xi	3.4678	C3A···C3^i	3.5555
S1···Tl1^i	3.3483	C3A···C2^i	3.5418
S1···Tl1^ii	3.2321	C3A···Tl1^xix	3.6304
Tl2^i—S1—C1	141.47	C1^iii—C3—H3	120.00
Tl1^ii—S1A—C1A	109.38	S1A—C1A—C2A	120.00
S1—C1—C2	120.00	S1A—C1A—C3A^ii	120.00
S1—C1—C3^iii	120.00	C2A—C1A—C3A^ii	120.00
C2—C1—C3^iii	120.00	C1A—C2A—C3A	120.00
C1—C2—C3	120.00	C1A^ii—C3A—C2A	120.00
C1^iii—C3—C2	120.00	C1A—C2A—H2A	120.00
C1—C2—H2	120.00	C3A—C2A—H2A	120.00
C3—C2—H2	120.00	C2A—C3A—H3A	120.00
C2—C3—H3	120.00	C1A^ii—C3A—H3A	120.00
Tl2^i—S1—C1—C2	24.88	C2—C1—C3^iii—C2^iii	0.00
Tl2^i—S1—C1—C3^iii	−155.12	C1—C2—C3—C1^iii	0.00
Tl1^ii—S1A—C1A—C3A^ii	126.01	S1A—C1A—C2A—C3A	180.00
Tl1^ii—S1A—C1A—C2A	−53.99	C3A^ii—C1A—C2A—C3A	−0.02
C3^iii—C1—C2—C3	0.00	S1A—C1A—C3A^ii—C2A^ii	180.00
S1—C1—C2—C3	179.98	C2A—C1A—C3A^ii—C2A^ii	0.02
S1—C1—C3^iii—C2^iii	−179.98	C1A—C2A—C3A—C1A^ii	0.00

Symmetry codes: (i) −x, −y+1, −z; (ii) −x+1, −y+1, −z; (iii) −x, −y, −z; (iv) −x+1, −y+2, −z; (v) x+1, y+1, z; (vi) x, y, z+1; (vii) x, y+1, z; (viii) x, y+1, z+1; (ix) x−1, y, z+1; (x) −x, −y+1, −z+1; (xi) −x, −y, −z−1; (xii) x, y−1, z−1; (xiii) x, y, z−1; (xiv) x+1, y, z−1; (xv) −x+1, −y+1, −z−1; (xvi) x+1, y, z; (xvii) x−1, y, z; (xviii) x−1, y−1, z; (xix) x, y−1, z.

(Tl2SeC6H4Se)

Crystal data

Tl2·(SeC6H2Se)	γ = 88.659 (3)°
Mr = 642.8	V = 426.72 (1) Å^3
Triclinic, P1	Z = 4
Hall symbol: P-1	Synchrotron radiation, λ = 0.699855 Å
a = 6.67438 (8) Å	T = 298 K
b = 6.84998 (8) Å	Particle morphology: fine powder
c = 9.82649 (10) Å	red-orange
α = 72.513 (2)°	flat sheet, 8 × 17 mm
β = 84.790 (2)°	Specimen preparation: Prepared at 298 K and 101.325 kPa, cooled at 0 K min^−1

Data collection

Huber diffractometer	Data collection mode: reflection
Radiation source: synchrotron, NSLS Beamline X16C	Scan method: step
Si (111) monochromator	2θmin = 3°, 2θmax = 40°, 2θstep = 0.005°
Specimen mounting: Flat plate geometry on zero-background holder.

Refinement

Rp = 0.049	94 parameters
Rwp = 0.056	0 restraints
Rexp = 0.020	H-atom parameters not refined
RBragg = 0.026	Weighting scheme based on measured s.u.'s
χ^2 = 7.756	(Δ/σ)max = 0.0001
7401 data points	Background function: Chebyshev polynomial with 8 coeffecients plus 1/(2theta) term
Excluded region(s): none	Preferred orientation correction: March-Dollase parameter 0.797(1) in (001) direction
Profile function: Simple_Axial_Model(width parameter 6.96/300) function with Rp=9999,Rs=300 in TOPAS-Academic

Special details

Experimental. In order to decrease sample absorption, the sample was mixed with finely ground cork before loading into the capillary. This diluted the sample to prevent absorption corrections as well as ensuring no preferred orientation.

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All suś are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

Refinement. The two Se(C6H4)Se moieties were refined as z-matrices, with planar regula hexagonal symmetry imposed for the aromatic rings, located at inversion centers. Se—C bond lengths were refined, but Se atoms were fixed in the planes of the hexagons, with Se—C—C bond angles fixed at 60 °.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Tl1	0.4477 (3)	0.9039 (3)	0.3539 (2)	0.0500*
Tl2	0.0419 (3)	0.5890 (3)	0.6465 (2)	0.0500*
Se1	0.06968	0.05017	−0.34935	0.0015 (7)*
Se1A	0.54913	0.55701	−0.35070	0.0015 (7)*
C1	0.03022	0.02176	−0.15151	0.0015 (7)*
C1A	0.52131	0.52473	−0.15209	0.0015 (7)*
C2	0.15899	−0.11212	−0.05330	0.0015 (7)*
C2A	0.38131	0.37526	−0.05822	0.0015 (7)*
C3	0.12877	−0.13388	0.09821	0.0015 (7)*
C3A	0.36000	0.35053	0.09387	0.0015 (7)*
H2	0.27768	−0.19582	−0.09309	0.0015 (7)*
H2A	0.29270	0.28213	−0.10169	0.0015 (7)*
H3	0.22490	−0.23382	0.17152	0.0015 (7)*
H3A	0.25548	0.23894	0.16394	0.0015 (7)*

Geometric parameters (Å, º)

Tl1—Se1^i	3.2388	C1A—C3A^i	1.4467
Tl1—Se1A^i	3.1664	C2—C3	1.4467
Tl2—Se1^ii	3.1815	C2A—C3A	1.4467
Se1—C1	1.8891	C2—H2	1.0800
Se1A—C1A	1.8891	C2A—H2A	1.0800
C1—C2	1.4467	C3—H3	1.0800
C1—C3^iii	1.4467	C3A—H3A	1.0800
C1A—C2A	1.4467
Tl1···Tl2	3.923 (3)	Se1···Tl1^vii	3.4633
Tl1···Se1^ii	4.0217	Se1···Tl2^vii	3.3408
Tl1···Se1A^iv	3.2660	Se1···Se1^xiii	3.4433
Tl1···C3^v	3.5070	Se1A···Tl2^xiv	3.2984
Tl1···C3A^v	3.4237	Se1A···Tl1^xii	3.2660
Tl1···Se1A^vi	3.6839	Se1A···Tl2^xii	3.3895
Tl1···C1^vii	3.8545	Se1A···Tl1^vi	3.6839
Tl1···Se1^vii	3.4633	Se1A···Se1A^xv	3.3765
Tl1···C1A^vi	3.8201	C1···Tl2^xii	3.7940
Tl2···Se1^vii	3.3408	C1···Tl1^vii	3.8545
Tl2···C3^viii	3.5010	C1···C3A^iii	3.5752
Tl2···C2A^iv	3.7656	C1A···C3^xvi	3.4616
Tl2···Tl1	3.923 (3)	C1A···Tl1^vi	3.8201
Tl2···Se1^iv	3.6794	C1A···Tl2^xiv	3.8056
Tl2···Se1A^ix	3.2984	C2A···Tl2^xii	3.7656
Tl2···Se1A^iv	3.3895	C3···Tl1^xvii	3.5070
Tl2···C1^iv	3.7940	C3···Tl2^viii	3.5010
Tl2···C1A^ix	3.8056	C3···C1A^xvi	3.4616
Tl2···C3A^x	3.6354	C3A···Tl2^x	3.6354
Se1···Tl1^xi	4.0217	C3A···C1^iii	3.5752
Se1···Tl2^xii	3.6794	C3A···Tl1^xvii	3.4237
Se1^i—Tl1—Se1A^i	96.33	C1A—C2A—C3A	120.00
Tl2^xi—Se1—C1	102.20	C1^iii—C3—C2	120.00
Tl1^i—Se1—C1	92.41	C1A^i—C3A—C2A	120.00
Tl1^i—Se1—Tl2^xi	100.07	C1—C2—H2	120.00
Tl1^i—Se1A—C1A	101.56	C3—C2—H2	120.00
Se1—C1—C2	120.00	C1A—C2A—H2A	120.00
Se1—C1—C3^iii	120.00	C3A—C2A—H2A	120.00
C2—C1—C3^iii	120.00	C2—C3—H3	120.00
Se1A—C1A—C2A	120.00	C1^iii—C3—H3	120.00
Se1A—C1A—C3A^i	120.00	C2A—C3A—H3A	120.00
C2A—C1A—C3A^i	120.00	C1A^i—C3A—H3A	120.00
C1—C2—C3	120.00
Tl2^xi—Se1—C1—C2	55.60	Se1—C1—C3^iii—C2^iii	−180.00
Tl2^xi—Se1—C1—C3^iii	−124.40	C2—C1—C3^iii—C2^iii	0.00
Tl1^i—Se1—C1—C2	−45.24	Se1A—C1A—C2A—C3A	180.00
Tl1^i—Se1—C1—C3^iii	134.76	C3A^i—C1A—C2A—C3A	0.00
Tl1^i—Se1A—C1A—C2A	−42.83	Se1A—C1A—C3A^i—C2A^i	180.00
Tl1^i—Se1A—C1A—C3A^i	137.17	C2A—C1A—C3A^i—C2A^i	0.00
Se1—C1—C2—C3	180.00	C1—C2—C3—C1^iii	0.00
C3^iii—C1—C2—C3	0.00	C1A—C2A—C3A—C1A^i	0.02

Symmetry codes: (i) −x+1, −y+1, −z; (ii) x, y+1, z+1; (iii) −x, −y, −z; (iv) x, y, z+1; (v) x, y+1, z; (vi) −x+1, −y+2, −z; (vii) −x, −y+1, −z; (viii) −x, −y, −z+1; (ix) x−1, y, z+1; (x) −x, −y+1, −z+1; (xi) x, y−1, z−1; (xii) x, y, z−1; (xiii) −x, −y, −z−1; (xiv) x+1, y, z−1; (xv) −x+1, −y+1, −z−1; (xvi) −x+1, −y, −z; (xvii) x, y−1, z.