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Acta Crystallogr Sect E Struct Rep Online. 2008 February 1; 64(Pt 2): m296–m297.
Published online 2008 January 4. doi:  10.1107/S1600536807067682
PMCID: PMC2960287

Bis(methyl­ammonium) tetra­sulfido­tungstate(VI)


The title compound, (CH6N)2[WS4], was synthesized by the reaction of ammonium tetra­sulfidotungstate(VI) with aqueous methyl­amine. The title compound is isotypic with the corresponding Mo analogue (CH6N)2[MoS4], and its structure consists of a slightly distorted tetra­hedral [WS4]2− dianion and two crystallographically independent methyl­ammonium (MeNH3) cations, all of which are located on crystallographic mirror planes. The tetra­sulfidotungstate anions are linked to the organic cations via hydrogen-bonding inter­actions.

Related literature

Previous reports give details of the structural characterization of several organic ammonium tetra­sulfidotungstates containing organic cations derived from a variety of amines (Srinivasan, Naik et al., 2007 [triangle] and related literature cited therein; Srinivasan, Girkar & Raghavaiah 2007 [triangle] and related literature cited therein). The title compound is isotypic with (NH4)2[WS4], (Srinivasan et al., 2004 [triangle]), Rb2[WS4] (Yao & Ibers, 2004 [triangle]), Cs2[WS4] (Srinivasan, Näther & Bensch 2007 [triangle]) and (CNH6)2[MoS4] (Srinivasan, Näther et al., 2006 [triangle]). For related literature, see: Bondi (1964 [triangle]); Jeffrey (1997 [triangle]).

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Object name is e-64-0m296-scheme1.jpg


Crystal data

  • (CH6N)2[WS4]
  • M r = 376.23
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-64-0m296-efi7.jpg
  • a = 9.5591 (10) Å
  • b = 7.0006 (7) Å
  • c = 15.734 (2) Å
  • V = 1052.9 (2) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 11.70 mm−1
  • T = 170 (2) K
  • 0.12 × 0.06 × 0.04 mm

Data collection

  • Stoe IPDS1 diffractometer
  • Absorption correction: numerical (X-SHAPE; Stoe & Cie, 1998 [triangle]) T min = 0.441, T max = 0.631
  • 9418 measured reflections
  • 1355 independent reflections
  • 1060 reflections with I > 2σ(I)
  • R int = 0.065


  • R[F 2 > 2σ(F 2)] = 0.032
  • wR(F 2) = 0.081
  • S = 1.10
  • 1355 reflections
  • 53 parameters
  • H-atom parameters constrained
  • Δρmax = 1.48 e Å−3
  • Δρmin = −2.34 e Å−3

Data collection: IPDS Program Package (Stoe & Cie, 1998 [triangle]); cell refinement: IPDS Program Package; data reduction: IPDS Program Package; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997 [triangle]); molecular graphics: DIAMOND (Brandenburg, 1999 [triangle]); software used to prepare material for publication: CIFTAB in SHELXTL (Bruker, 1998 [triangle]).

Table 1
Selected geometric parameters (Å, °)
Table 2
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536807067682/si2066sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536807067682/si2066Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report


BRS thanks Mr R. G. Mhalsikar and Mr A. R. Naik for the preparation of the crystals of the title compound, and the Department of Science and Technology (DST), New Delhi, India, for financial support.

supplementary crystallographic information


In continuation of our recent reports on the synthesis and structural characterization of organic ammonium tetrasulfidotungstates (Srinivasan, Naik et al., 2007 and related literature cited therein; Srinivasan, Girkar & Raghavaiah 2007) we describe herein the structure of a new organic [WS4]2- compound containing methylammonium as counter cation.

The title compound is isostructural with (NH4)2[WS4], (Srinivasan et al., 2004), Cs2[WS4] (Srinivasan, Näther & Bensch 2007), Rb2[WS4] (Yao & Ibers 2004), and (CH6N)2[MoS4] (Srinivasan,, Näther et al., 2006). The structure consists of a discrete tetrahedral [WS4]2- ion and two crystallographically independent methylammonium cations (Fig. 1) all of which are located on crystallographic mirror planes so that each half of these ions make up the asymmetric unit. The bond lengths and bond angles of the organic cations are in good agreement with the reported values for the isotypic Mo compound. The WS4 tetrahedron is slightly distorted with S—W—S angles between 108.46 (7) and 110.45 (5) ° (Table 1). The W—S bond lengths range from 2.1862 (13) to 2.2010 (18) Å with an average value of 2.1931 Å. The observed difference Δ between the longest and the shortest W—S bonds of 0.0148 Å in the title compound is slightly shorter than the Δ value of 0.0199 Å in the analogous Mo compound (CNH6)2[MoS4] (Srinivasan, Näther et al., 2006).

A scrutiny of the structure reveals that each [WS4]2- is hydrogen bonded to ten symmetry related organic cations via several weak N—H···S and C—H···S interactions (Fig.2). These weak interactions can explain the observed distinct W—S bond distances. In general, unshared H-bonds have a considerably stronger effect than bifurcated ones, while the effect of trifurcated H-bonds is quite weak (Jeffrey, 1997). The atoms H1N1 and H2N1 are involved in bifurcated H-bonding while H1N2 makes a trifurcated H-bond, and H2N2 forms an unshared H-bond. Although short S···H contacts are observed at 2.40 and 2.55 Å for S2 and S1 respectively, these are relatively weaker in view of the bifurcated nature of H-bonding and hence do not cause much lengthening of these W—S bonds. The weakness of the trifurcated H-bond can also be evidenced from the observed longer S···H distances accompanied by smaller N—H···S angles. S3 is involved in a singly unshared H-bond at a distance of 2.64 Å. The effect of this contact is stronger than all the other contacts and can explain the elongation of the W—S3 bond, the longest observed W—S distance for the title compound. In all ten short S···H contacts ranging from 2.40 to 2.97 Å, all of which are shorter than the sum of their van der Waals radii (Bondi, 1964) are observed (Table 2). As a result of H-bonding, the organic cations are organized such that the ammonium groups always point towards the S atoms of tetrasulfidotungstate as can be seen in the sequence in the crystallographic bc plane viz. WS4··· H3NMe··· MeNH3··· WS4··· and so on (Fig. 3).


(NH4)2[WS4] (1 g) was dissolved in 40% methylamine (5 ml) and water (2 ml) and filtered. The clear yellow filtrate was left undisturbed for crystallization. After a day crystalline blocks of the title compound separated. The product was filtered, washed with ice-cold water (1 ml), followed by 2-propanol (5 ml) and diethyl ether (10 ml) and dried. Yield: 1.1 g.


All H atoms were located in difference map but were positioned with idealized geometry ((CH3 and NH3 allowed to rotate but not to tip) with 0.98 and 0.96 Å (methyl) and N—H = 0.91 Å) and were refined using a riding model, with Uiso(H) fixed at 1.5Ueq(CH3 and NH3). The largest peak in the residual electron density map of 1.48 e Å-3 is located at a distance of 0.09 Å from W1 and the deepest hole of -2.34 e Å-3 is located at a distance of 0.83 Å from W1.


Fig. 1.
Perspective view of the title compound showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level. Symmetry code: (i) x, -y + 1/2, z
Fig. 2.
A view of the surroundings of the [WS4]2- anion showing its linking to ten different organic cations with the aid of N—H···S and C—H···S interactions. Symmetry codes: (i) x, -y + 1/2, Z (ii) ...
Fig. 3.
A view of the crystallographic packing of the title compound along the a axis, showing the organization of the organic cations and [WS4]2- anions. H-bonds are shown as broken lines.

Crystal data

(CH6N)2[WS4]F000 = 704
Mr = 376.23Dx = 2.373 Mg m3
Orthorhombic, PnmaMo Kα radiation λ = 0.71073 Å
Hall symbol: -P 2ac 2nCell parameters from 8000 reflections
a = 9.5591 (10) Åθ = 1.9–28.2º
b = 7.0006 (7) ŵ = 11.70 mm1
c = 15.734 (2) ÅT = 170 (2) K
V = 1052.9 (2) Å3Block, yellow
Z = 40.12 × 0.06 × 0.04 mm

Data collection

Stoe IPDS1 diffractometer1355 independent reflections
Radiation source: fine-focus sealed tube1060 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.065
T = 170(2) Kθmax = 27.9º
[var phi] scansθmin = 2.5º
Absorption correction: Numerical(X-SHAPE; Stoe & Cie, 1998)h = −12→12
Tmin = 0.441, Tmax = 0.631k = −9→9
9418 measured reflectionsl = −20→20


Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.032  w = 1/[σ2(Fo2) + (0.045P)2 + 1.2501P] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.081(Δ/σ)max < 0.001
S = 1.10Δρmax = 1.48 e Å3
1355 reflectionsΔρmin = −2.34 e Å3
53 parametersExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0022 (3)
Secondary atom site location: difference Fourier map

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 (Å2)

W10.24968 (3)0.25000.552442 (15)0.01100 (14)
S30.02612 (18)0.25000.58592 (13)0.0191 (4)
S20.2751 (2)0.25000.41353 (13)0.0209 (4)
S10.35291 (14)−0.00338 (18)0.60404 (9)0.0204 (3)
N1−0.0570 (7)0.25000.3764 (4)0.0178 (13)
C1−0.0349 (12)0.25000.2832 (6)0.041 (2)
N20.6638 (7)0.25000.5893 (4)0.0233 (14)
C20.6709 (10)0.25000.6828 (5)0.0282 (18)

Atomic displacement parameters (Å2)

W10.00838 (19)0.01006 (18)0.01455 (19)0.000−0.00081 (11)0.000
S30.0086 (8)0.0257 (9)0.0230 (9)0.0000.0029 (8)0.000
S20.0157 (9)0.0286 (9)0.0183 (9)0.0000.0028 (8)0.000
S10.0166 (6)0.0131 (5)0.0316 (6)0.0016 (5)−0.0057 (6)0.0043 (5)
N10.016 (3)0.016 (3)0.021 (3)0.000−0.006 (3)0.000
C10.048 (6)0.058 (6)0.016 (4)0.0000.003 (4)0.000
N20.017 (3)0.025 (3)0.028 (4)0.0000.005 (3)0.000
C20.027 (5)0.037 (4)0.021 (4)0.0000.002 (4)0.000

Geometric parameters (Å, °)

W1—S1i2.1862 (13)C1—H1A0.98
W1—S12.1862 (13)C1—H1B0.96
W1—S22.199 (2)N2—C21.473 (11)
W1—S32.2010 (18)N2—H1N20.91
N1—C11.482 (10)N2—H2N20.91
S1i—W1—S1108.46 (7)N1—C1—H1A111.0
S1i—W1—S2108.62 (5)N1—C1—H1B104.1
S1—W1—S2108.62 (5)H1A—C1—H1B110.9
S1i—W1—S3110.45 (5)C2—N2—H1N2109.4
S1—W1—S3110.45 (5)C2—N2—H2N2109.8
S2—W1—S3110.18 (8)H1N2—N2—H2N2110.2

Symmetry codes: (i) x, −y+1/2, z.

Hydrogen-bond geometry (Å, °)

N1—H1N1···S1ii0.912.553.328 (6)144
N1—H1N1···S3ii0.912.903.5623 (12)131
N1—H2N1···S20.912.403.227 (7)152
N1—H2N1···S30.912.833.390 (7)121
N2—H1N2···S10.912.773.468 (6)135
N2—H1N2···S1iii0.912.953.502 (6)121
N2—H1N2···S2iii0.912.963.5491 (12)124
N2—H2N2···S3iv0.912.643.464 (7)151
C1—H1A···S1v0.982.973.736 (8)135
C1—H1B···S2vi0.962.893.589 (10)131

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


Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: SI2066).


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