TlSrPS₄, the first strontium quaternary thio­phosphate

The new thallium(I) strontium(II) thio­phosphate TlSrPS₄ is isostructural with TlPbPS₄ and exhibits a layered structure. Each layer is composed of [(SrS₆)(TlS₆)]_n zigzag chains, which consist of irregular trigonal prisms centred alternately by Tl and Sr atoms. Adjacent [TlS₆] and [SrS₆] prisms share common triangular faces to form one-dimensional chains parallel to [001]. These chains are connected along [010] by sharing edges of recta­ngular faces in such a way that the apical edges of the prisms point alternately up and down, forming parallel zigzag layers. The layers are stacked perpendicular to the crystallographic a axis and are held together by [PS₄] tetra­hedra.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](S-P) = 0.003 Å
• R factor = 0.033
• wR factor = 0.084
• Data-to-parameter ratio = 22.8

checkCIF/PLATON results

No syntax errors found



Alert level G
ABSTM02_ALERT_3_G  The ratio of expected to reported Tmax/Tmin(RR') is < 0.50
            Tmin and Tmax reported:      0.018     0.111
            Tmin(prime) and Tmax expected:      0.069     0.153
            RR(prime) =      0.349
            Please check that your absorption correction is appropriate.
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K
PLAT794_ALERT_5_G Check Predicted Bond Valency for Tl1         (1)       0.94

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   0 ALERT level C = Check and explain
   4 ALERT level G = General alerts; check

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

In our effort to extend the range of quaternary ortho-thiophosphate, AMPS₄ (A = K, Rb, Cs, Tl and M: divalent metal) (Belkyal et al., 2005 and 2006a), the new compound TlSrPS₄ was obtained. Neither the structure nor the properties of strontium quaternary thiophosphates have been known until now. The title compound crystallizes in the centrosymmetric space group Pnma and is isostructural with TlPbPS₄ (Belkyal et al., 2006b) and is closely related to those of the other thallium tetrathiophosphate namely TlEuPS₄ (Carrillo-Cabrera et al., 1995) and TlSnPS₄ (Becker et al., 1987).

The asymmetric unit of the title compound is plotted on Fig. 1. The structure of TlSrPS₄ has a pseudo two-dimensional character. Looking down the c axis (Fig. 2), one can see layers of [(SrS₆)(TlS₆)]_n separated by P⁵⁺ cations. These geometric parameters are in agreement with values reported in the literature for TlPbPS₄ (Belkyal et al., 2006b) or TlEuPS₄ (Carrillo-Cabrera et al., 1995).

The layers are composed of wedge-like irregular trigonal prisms alternately centred by Tl and Sr atoms. Adjacent prisms TlS₆ and SrS₆ share edges of rectangular faces in such a way that edges of the prisms point alternately up and down forming one-dimensional parallel zigzag chains along [010] (Fig. 3). These zigzag chains are joined together by sharing the triangular faces along [001], in such way that the TlS₆ prism of one chain shares triangular face with SrS₆ prism of the other chain. Thus, the layers formed are connected by [PS₄] tetrahedra along [100]. The P—S bonds, within the [PS₄] tetrahedra, are almost equidistant from 2.031 (3) to 2.044 (2) Å. The average of these distances is in good agreement with those found in TlPbPS₄ [Belkyal et al., 2006b] or TlEuPS₄ (Carrillo-Cabrera et al., 1995). The Tl—S bond lengths found in TlSrPS₄ range from 3.268 (1) to 3.397 (3) Å and compare very well with those reported for TlPbPS₄ (Belkyal et al., 2006b). Whereas the Sr—S distances (2.984 (3) to 3,095 (2) Å) are smaller than those found in the strontium ternary compound Sr₂P₂S₆ (Hadenfeldt & Hoedel, 1996) (3,058 (2)–3.200 (1) Å). This reduction is the result of the increase in the covalent character of the Sr—S bond in TlSrPS₄. The same behavior was observed for the Pb—S distances between TlPbPS₄ (Belkyal et al., 2006b) and Pb₂P₂S₆ (Hadenfeldt & Hoedel, 1996)·The average Tl—S and Sr—S distances in TlSrPS₄ match well with the sum of the ionic radii (Shannon, 1976).

Related literature

Background information on related structures can be found in Belkyal, El Azhari, Bensch & Depmeier (2006), Carrillo-Cabrera et al. (1995) and Becker et al. (1987).

For related literature, see: Belkyal et al. (2005); Belkyal, El Azhari, Wu et al. (2006); Hadenfeldt & Hoedel (1996); Horn & Sterzel (1973); Johri et al. (1970); Shannon (1976).

S2. Experimental

TlSrPS₄ was prepared from a stochiometric mixture of P₂S₅ (99,99%, Alfa), SrS (99,9%, ABCR), S (99,99%, Heraeus) and Tl₂S. The latter was prepared by thermal decomposition of Tl₂CS₃ (Horn & Sterzel, 1973; Johri et al., 1970) in argon atmosphere under reduced pressure at Tmax = 523 K. The reaction mixture was thoroughly mixed in a N₂-filled glove box and loaded into a quartz ampoule. After evacuation to 10^-3 mbar the ampoule was flame-sealed and placed in a computer controlled furnace. The sample was heated to 1200 K, kept at this temperature for 5 days, cooled to 400 K at a rate of 4.8 °K/h, then turned off the furnace. After washing with ether transparent orange platelets were obtained. The compound is slightly air and moisture sensitive. An EDX analysis indicated the presence of all four elements (Tl, Sr, P, S) in an approximate atomic ratio of 1:1:1:4. The EDX analysis was performed using a Philips ESEM XL 30 scanning electron microscope equipped with an EDAX analyser.

Computing details

Data collection: IPDS (Stoe & Cie, 1998); cell refinement: IPDS; data reduction: IPDS; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997) and BS (Version 1.51; Ozawa & Kang, 2004); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. The asymmetric unit of the title compound, with anisotropic displacement parameters drawn at the 50% probability level.
	Fig. 2. Extended structure of TlSrPS4 projected along [001].
	Fig. 3. Projection along [001], showing the puckered layer of condensed chains of SrS6 and TlS6 trigonal prisms.

Thallium strontium tetrathiophosphate

Crystal data

TlSrPS4	F(000) = 792
Mr = 451.20	Dx = 4.198 Mg m^−3
Orthorhombic, Pnma	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2n	Cell parameters from 935 reflections
a = 12.2985 (8) Å	θ = 2.9–27.9°
b = 6.6003 (6) Å	µ = 31.28 mm^−1
c = 8.7957 (6) Å	T = 293 K
V = 713.98 (9) Å^3	Platelet, orange
Z = 4	0.08 × 0.07 × 0.06 mm

Data collection

Stoe IPDS diffractometer	935 independent reflections
Radiation source: fine-focus sealed tube	780 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.099
φ scans	θmax = 27.9°, θmin = 2.9°
Absorption correction: numerical (X-SHAPE; Stoe & Cie, 1998)	h = −15→16
Tmin = 0.018, Tmax = 0.111	k = −8→8
6570 measured reflections	l = −11→11

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.033	w = 1/[σ^2(Fo^2) + (0.0408P)^2 + 3.1599P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.084	(Δ/σ)max = 0.001
S = 1.03	Δρmax = 1.46 e Å^−3
935 reflections	Δρmin = −2.30 e Å^−3
41 parameters	Extinction correction: SHELXL97 (Sheldrick, 1997)
0 restraints	Extinction coefficient: 0.0033 (3)

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Tl1	0.3980 (1)	0.7500	0.6257 (1)	0.031 (1)
Sr1	0.6395 (1)	0.2500	0.8923 (1)	0.016 (1)
P1	0.3468 (2)	0.2500	0.8764 (2)	0.012 (1)
S1	0.4445 (2)	0.2500	0.6903 (3)	0.020 (1)
S2	0.4310 (2)	0.2500	1.0761 (2)	0.018 (1)
S3	0.2472 (1)	0.0025 (2)	0.8659 (2)	0.018 (1)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Tl(1)	0.035 (1)	0.036 (1)	0.022 (1)	0.000	−0.003 (1)	0.000
Sr(1)	0.015 (1)	0.021 (1)	0.013 (1)	0.000	0.001 (1)	0.000
P(1)	0.015 (1)	0.008 (1)	0.013 (1)	0.000	−0.001 (1)	0.000
S(1)	0.021 (1)	0.026 (1)	0.013 (1)	0.000	0.002 (1)	0.000
S(2)	0.016 (1)	0.027 (1)	0.011 (1)	0.000	−0.002 (1)	0.000
S(3)	0.020 (1)	0.010 (1)	0.025 (1)	−0.004 (1)	−0.007 (1)	0.002 (1)

Geometric parameters (Å, º)

Tl1—Sr1^i	4.2645 (9)	Sr1—Tl1^i	4.2645 (9)
Sr1—S1	2.984 (3)	P1—S1	2.031 (3)
Sr1—S2	3.031 (2)	P1—S2	2.039 (3)
Sr1—S3^ii	3.0406 (18)	P1—S3	2.044 (2)
Sr1—S3^iii	3.0406 (18)	P1—S3^vi	2.044 (2)
Sr1—S3^iv	3.0951 (18)	P1—Sr1^vii	3.476 (2)
Sr1—S3^v	3.0951 (18)	S2—Sr1^iii	3.4234 (7)
Sr1—S2^iii	3.4234 (7)	S2—Sr1^i	3.4234 (7)
Sr1—S2^i	3.4234 (7)	S3—Sr1^iii	3.0406 (18)
Sr1—P1^iv	3.476 (2)	S3—Sr1^vii	3.0951 (18)
Sr1—P1	3.603 (2)
S1—Sr1—S2	68.77 (6)	S3^iv—Sr1—P1	113.53 (5)
S1—Sr1—S3^ii	141.70 (4)	S3^v—Sr1—P1	113.53 (5)
S2—Sr1—S3^ii	90.84 (5)	S2^iii—Sr1—P1	75.53 (4)
S1—Sr1—S3^iii	141.70 (4)	S2^i—Sr1—P1	75.53 (4)
S2—Sr1—S3^iii	90.84 (5)	P1^iv—Sr1—P1	134.94 (4)
S3^ii—Sr1—S3^iii	66.47 (6)	S1—Sr1—Tl1^i	120.33 (5)
S1—Sr1—S3^iv	84.67 (5)	S2—Sr1—Tl1^i	51.57 (4)
S2—Sr1—S3^iv	138.88 (4)	S3^ii—Sr1—Tl1^i	49.76 (4)
S3^ii—Sr1—S3^iv	127.32 (3)	S3^iii—Sr1—Tl1^i	49.76 (4)
S3^iii—Sr1—S3^iv	91.588 (16)	S3^iv—Sr1—Tl1^i	140.86 (4)
S1—Sr1—S3^v	84.67 (5)	S3^v—Sr1—Tl1^i	140.86 (4)
S2—Sr1—S3^v	138.88 (4)	S2^iii—Sr1—Tl1^i	83.79 (4)
S3^ii—Sr1—S3^v	91.588 (16)	S2^i—Sr1—Tl1^i	83.79 (4)
S3^iii—Sr1—S3^v	127.32 (3)	P1^iv—Sr1—Tl1^i	139.03 (4)
S3^iv—Sr1—S3^v	63.71 (6)	P1—Sr1—Tl1^i	86.02 (4)
S1—Sr1—S2^iii	81.08 (4)	S1—P1—S2	113.15 (14)
S2—Sr1—S2^iii	75.08 (4)	S1—P1—S3	108.56 (10)
S3^ii—Sr1—S2^iii	125.99 (5)	S2—P1—S3	110.09 (9)
S3^iii—Sr1—S2^iii	62.02 (5)	S1—P1—S3^vi	108.56 (10)
S3^iv—Sr1—S2^iii	70.08 (5)	S2—P1—S3^vi	110.09 (9)
S3^v—Sr1—S2^iii	132.59 (5)	S3—P1—S3^vi	106.13 (13)
S1—Sr1—S2^i	81.08 (4)	S1—P1—Sr1^vii	83.47 (10)
S2—Sr1—S2^i	75.08 (4)	S2—P1—Sr1^vii	163.37 (12)
S3^ii—Sr1—S2^i	62.02 (5)	S3—P1—Sr1^vii	61.95 (7)
S3^iii—Sr1—S2^i	125.99 (5)	S3^vi—P1—Sr1^vii	61.95 (7)
S3^iv—Sr1—S2^i	132.59 (5)	S1—P1—Sr1	55.92 (9)
S3^v—Sr1—S2^i	70.08 (5)	S2—P1—Sr1	57.23 (9)
S2^iii—Sr1—S2^i	149.15 (8)	S3—P1—Sr1	126.91 (7)
S1—Sr1—P1^iv	100.63 (6)	S3^vi—P1—Sr1	126.90 (7)
S2—Sr1—P1^iv	169.40 (6)	Sr1^vii—P1—Sr1	139.40 (6)
S3^ii—Sr1—P1^iv	98.01 (5)	P1—S1—Sr1	89.77 (10)
S3^iii—Sr1—P1^iv	98.01 (5)	P1—S2—Sr1	88.31 (10)
S3^iv—Sr1—P1^iv	35.64 (3)	P1—S2—Sr1^iii	86.63 (5)
S3^v—Sr1—P1^iv	35.64 (3)	Sr1—S2—Sr1^iii	104.92 (4)
S2^iii—Sr1—P1^iv	103.94 (4)	P1—S2—Sr1^i	86.63 (5)
S2^i—Sr1—P1^iv	103.94 (4)	Sr1—S2—Sr1^i	104.92 (4)
S1—Sr1—P1	34.31 (6)	Sr1^iii—S2—Sr1^i	149.15 (8)
S2—Sr1—P1	34.46 (5)	P1—S3—Sr1^iii	97.57 (8)
S3^ii—Sr1—P1	119.03 (5)	P1—S3—Sr1^vii	82.41 (7)
S3^iii—Sr1—P1	119.03 (5)	Sr1^iii—S3—Sr1^vii	177.14 (7)

Symmetry codes: (i) −x+1, −y+1, −z+2; (ii) −x+1, y+1/2, −z+2; (iii) −x+1, −y, −z+2; (iv) x+1/2, y, −z+3/2; (v) x+1/2, −y+1/2, −z+3/2; (vi) x, −y+1/2, z; (vii) x−1/2, y, −z+3/2.