Download citation
Download citation
link to html
The crystal structure of dicaesium pentadecamolybdenum nonadeca­sulfide, Cs2Mo15S19, consists of a mixture of Mo6S8S6 and Mo9S11S6 cluster units in a 1:1 ratio. Both units are interconnected via inter-unit Mo-S bonds. The Cs+ cations occupy large voids between the different cluster units. The Cs and two inner S atoms lie on sites with 3 symmetry (Wyckoff site 12c) and the Mo and S atoms of the median plane of the Mo9S11S6 cluster unit on sites with 2 symmetry (Wyckoff site 18e).

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270104008248/iz1041sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270104008248/iz1041Isup2.hkl
Contains datablock I

Comment top

In a previous paper, we presented the syntheses, crystal structures and physical properties of the series of compounds Rb2nMo9S11Mo6nS6n+2 (n = 1, 2, 3 and 4; Picard et al., 2000). Their crystal structures consist of an equal mixture of Mo9S11 and Mo6nS6n+2 (n = 1 to 4) cluster units interconnected via Mo—S bonds. The Rb+ cations occupy large voids between the different cluster units. The interest of these Mo cluster compounds lies not only in their fascinating structural aspect, but also in their interesting physical properties. Indeed, the Rb2nMo9S11Mo6nS6n+2 (n = 1, 2, 3, and 4) compounds are superconducting, with critical temperatures ranging from 4.2 to 11 K.

In the Cs—Mo—S system, we reported, a decade ago, the crystal structure of Cs4Mo21S25 (Gougeon & Potel, 1993), which constitutes the second member of the series Cs2nMo9S11Mo6nS6n+2, and, recently, that of the third member, Cs6Mo27S31 (Picard et al., 2003). We present here the crystal structure of Cs2Mo15S19.

The title compound (Fig. 1) is isostructural with In2Mo15Se19 (Potel et al., 1981) and constitutes the first member of the Cs2nMo9S11Mo6nS6n+2 series. Its crystal structure contains Mo6Si8Sa6 and Mo9Si11Sa6 cluster units in equal proportion. The i-type ligands cap Mo triangular faces and the a-type ones are in apical positions for the external Mo atoms (Fig. 2).

The Mo9S11 and Mo6S8 cluster units are centred at 6a (D3 or 32 symmetry) and 6 b positions (S6 or 3 symmetry), respectively. The Mo—Mo distances within the Mo6 clusters are 2.6854 (4) Å for the intra-triangle distances (distances within the Mo3 triangles formed by the Mo atoms related through the threefold axis) and 2.7629 (3) Å for the inter-triangle distances. The Mo—Mo distances within the Mo9 clusters are 2.6823 (3) and 2.6893 (5) Å for the intra-triangle distances between the Mo1 and Mo2 atoms, respectively, and 2.7271 (2) and 2.7826 (2) Å for those between the Mo3 triangles.

The S atoms bridge either one (atoms S1, S3, S4 and S5) or two (atom S2) Mo triangular faces of the clusters. Moreover, atoms S1 and S3 are linked to an Mo atom of a neighbouring cluster. The Mo—S bond distances range from 2.4170 (8) to 2.4725 (6) Å within the Mo6S8 unit and from 2.3977 (6) to 2.6240 (5) Å within the Mo9S11 unit. Compared with Rb2Mo15S19, the Mo—Mo and Mo—S distances in both units are quite similar to those observed in the Rb analogue, since the greatest differences are 0.006 and 0.01 Å for the Mo—Mo and Mo—S bonds, respectively. This clearly shows that the number of electrons per Mo6 and Mo9 cluster should be almost the same in both compounds.

Each Mo9S11 unit is interconnected to six Mo6S8 units (and vice versa) via Mo1—S3 bonds (or Mo3—S1 bonds, respectively) to form the three-dimensional Mo—S framework, the connective formula of which is Mo9Si5Si-a6/2Sa-i6/2, Mo6Si2Si-a6/2Sa-i6/2. The results of this arrangement is that the shortest intercluster Mo1—Mo3 distances between the Mo6 and Mo9 clusters is 3.2934 (3) Å, indicating only a weak metal-metal interaction. This value is slightly larger than the value of 3.246 (2) Å observed for Rb2Mo15S19, as expected from the larger size of the Cs+ cations.

The alkali-metal cations are in a penta-capped trigonal prismatic environment of S atoms (Fig. 3). The Cs—S distances span a wide range, 3.2825 (6)–3.7497 (6) Å.

Cs2Mo15S19 was found to be superconducting at 2.7 K (4.2 K for Rb2Mo15S19) from dc susceptibility measurements on a batch of single crystals.

Experimental top

Single crystals of Cs2Mo15S19 were prepared from a stoichiometric mixture of Cs2MoS4, MoS2 and Mo. All handling of materials was done in an argon-filled glove box. The initial mixture (ca 5 g) was cold pressed and loaded into a molybdenum crucible, which was sealed under a low argon pressure using an arc welding system. The charge was heated at a rate of 300 K h−1 up to 1773 K, held at that temperature for 48 h, cooled at 100 K h−1 down to 1373 K and finally furnace cooled.

Computing details top

Data collection: COLLECT (Nonius, 1998); cell refinement: COLLECT; data reduction: EVALCCD (Duisenberg, 1998); program(s) used to solve structure: Please provide missing details; program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Bergerhoff, 1996); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. A view of Cs2Mo15S19 along [110].
[Figure 2] Fig. 2. A plot showing the atom-numbering scheme and the interunit linkage of the Mo9S11S6 and Mo6S8S6 cluster units in Cs2Mo15S19. Displacement ellipsoids are drawn at the 97% probability level. Symmetry codes are as in Table 1.
[Figure 3] Fig. 3. The environment of the Cs+ ion. Symmetry codes are as in Table 1.
Dicaesium pentadecamolybdenum nonadecasulfide top
Crystal data top
Cs2Mo15S19Dx = 5.227 Mg m3
Mr = 2314.06Mo Kα radiation, λ = 0.71069 Å
Hexagonal, R3cCell parameters from 22219 reflections
a = 9.5012 (1) Åθ = 2.9–40.3°
c = 56.4199 (6) ŵ = 9.94 mm1
V = 4410.82 (8) Å3T = 293 K
Z = 6Irregular block, black
F(000) = 62640.34 × 0.25 × 0.21 mm
Data collection top
Nonius KappaCCD area-detector
diffractometer
3042 independent reflections
Radiation source: fine-focus sealed tube2575 reflections with I > 2σ(I)
Horizontally mounted graphite crystal monochromatorRint = 0.067
Detector resolution: 9 pixels mm-1θmax = 39.9°, θmin = 2.2°
type of scansh = 1617
Absorption correction: analytical
(de Meulenaar & Tompa, 1965)
k = 1517
Tmin = 0.098, Tmax = 0.203l = 101101
33032 measured reflections
Refinement top
Refinement on F2Primary atom site location: isomorphous structure methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.030 w = 1/[σ2(Fo2) + (0.0187P)2 + 51.7289P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.062(Δ/σ)max = 0.002
S = 1.16Δρmax = 2.99 e Å3
3042 reflectionsΔρmin = 1.98 e Å3
57 parametersExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.000784 (16)
Crystal data top
Cs2Mo15S19Z = 6
Mr = 2314.06Mo Kα radiation
Hexagonal, R3cµ = 9.94 mm1
a = 9.5012 (1) ÅT = 293 K
c = 56.4199 (6) Å0.34 × 0.25 × 0.21 mm
V = 4410.82 (8) Å3
Data collection top
Nonius KappaCCD area-detector
diffractometer
3042 independent reflections
Absorption correction: analytical
(de Meulenaar & Tompa, 1965)
2575 reflections with I > 2σ(I)
Tmin = 0.098, Tmax = 0.203Rint = 0.067
33032 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0300 restraints
wR(F2) = 0.062 w = 1/[σ2(Fo2) + (0.0187P)2 + 51.7289P]
where P = (Fo2 + 2Fc2)/3
S = 1.16Δρmax = 2.99 e Å3
3042 reflectionsΔρmin = 1.98 e Å3
57 parameters
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
Cs0.33330.66670.219796 (6)0.01652 (6)
Mo10.00691 (2)0.15943 (2)0.209645 (4)0.00786 (5)
Mo20.16342 (3)0.00000.25000.00721 (5)
Mo30.50467 (3)0.82024 (2)0.313065 (3)0.00781 (4)
S10.71265 (7)1.01501 (8)0.286213 (11)0.00997 (10)
S20.30005 (9)1.00000.25000.01092 (14)
S30.01941 (7)0.36610 (7)0.183285 (11)0.00943 (10)
S40.00000.00000.176709 (18)0.01162 (17)
S50.33330.66670.280200 (19)0.01283 (18)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cs0.01516 (8)0.01516 (8)0.01924 (13)0.00758 (4)0.0000.000
Mo10.00787 (8)0.00754 (8)0.00777 (8)0.00356 (6)0.00049 (5)0.00058 (5)
Mo20.00720 (8)0.00742 (10)0.00707 (10)0.00371 (5)0.00040 (4)0.00079 (7)
Mo30.00893 (8)0.00797 (8)0.00730 (8)0.00480 (6)0.00081 (6)0.00067 (5)
S10.0092 (2)0.0103 (2)0.0112 (2)0.00553 (19)0.00202 (17)0.00139 (18)
S20.0087 (2)0.0129 (3)0.0126 (3)0.00646 (17)0.00095 (13)0.0019 (3)
S30.0078 (2)0.0106 (2)0.0105 (2)0.00507 (18)0.00059 (17)0.00139 (18)
S40.0136 (3)0.0136 (3)0.0076 (4)0.00682 (13)0.0000.000
S50.0160 (3)0.0160 (3)0.0066 (4)0.00798 (14)0.0000.000
Geometric parameters (Å, º) top
Cs—S1i3.2825 (6)Mo1—Mo3vii3.2934 (3)
Cs—S1ii3.2825 (6)Mo2—S1x2.3977 (6)
Cs—S1iii3.2825 (6)Mo2—S1vii2.3977 (6)
Cs—S53.4080 (11)Mo2—S2v2.4721 (7)
Cs—S4iv3.5640 (11)Mo2—S2xi2.4721 (7)
Cs—S2v3.7465 (5)Mo2—Mo2ix2.6893 (5)
Cs—S23.7465 (5)Mo2—Mo2viii2.6893 (5)
Cs—S2vi3.7465 (5)Mo2—Mo1xii2.7271 (2)
Cs—S3vi3.7497 (6)Mo2—Mo1xiii2.7826 (2)
Cs—S33.7497 (6)Mo2—Mo1viii2.7826 (2)
Cs—S3v3.7497 (6)Mo3—S52.4170 (8)
Mo1—S42.4189 (8)Mo3—S12.4429 (6)
Mo1—S1iii2.4328 (6)Mo3—S3xiv2.4481 (6)
Mo1—S1vii2.4554 (7)Mo3—S3xv2.4703 (6)
Mo1—S32.5130 (6)Mo3—S3xvi2.4725 (6)
Mo1—S2v2.6240 (5)Mo3—Mo3v2.6854 (4)
Mo1—Mo1viii2.6823 (3)Mo3—Mo3vi2.6854 (4)
Mo1—Mo1ix2.6823 (3)Mo3—Mo3xvii2.7629 (3)
Mo1—Mo22.7271 (2)Mo3—Mo3xviii2.7629 (3)
Mo1—Mo2ix2.7826 (2)
S1i—Cs—S1ii118.947 (4)S1i—Cs—S3vi62.815 (14)
S1i—Cs—S1iii118.947 (4)S1ii—Cs—S3vi60.821 (14)
S1ii—Cs—S1iii118.947 (4)S1iii—Cs—S3vi140.730 (17)
S1i—Cs—S595.929 (12)S5—Cs—S3vi123.324 (10)
S1ii—Cs—S595.929 (12)S4iv—Cs—S3vi56.677 (10)
S1iii—Cs—S595.929 (12)S2v—Cs—S3vi138.889 (13)
S1i—Cs—S4iv84.072 (12)S2—Cs—S3vi61.551 (10)
S1ii—Cs—S4iv84.071 (12)S2vi—Cs—S3vi118.203 (15)
S1iii—Cs—S4iv84.071 (12)S1i—Cs—S360.821 (14)
S5—Cs—S4iv180.0S1ii—Cs—S3140.730 (17)
S1i—Cs—S2v76.345 (15)S1iii—Cs—S362.815 (14)
S1ii—Cs—S2v156.265 (14)S5—Cs—S3123.324 (10)
S1iii—Cs—S2v57.425 (15)S4iv—Cs—S356.676 (10)
S5—Cs—S2v62.944 (5)S2v—Cs—S361.551 (10)
S4iv—Cs—S2v117.055 (6)S2—Cs—S3118.203 (15)
S1i—Cs—S257.425 (15)S2vi—Cs—S3138.889 (13)
S1ii—Cs—S276.345 (15)S3vi—Cs—S392.710 (14)
S1iii—Cs—S2156.265 (14)S1i—Cs—S3v140.730 (17)
S5—Cs—S262.944 (5)S1ii—Cs—S3v62.815 (14)
S4iv—Cs—S2117.056 (5)S1iii—Cs—S3v60.821 (14)
S2v—Cs—S2100.933 (7)S5—Cs—S3v123.324 (10)
S1i—Cs—S2vi156.265 (14)S4iv—Cs—S3v56.675 (10)
S1ii—Cs—S2vi57.425 (15)S2v—Cs—S3v118.203 (15)
S1iii—Cs—S2vi76.345 (15)S2—Cs—S3v138.889 (13)
S5—Cs—S2vi62.944 (5)S2vi—Cs—S3v61.551 (10)
S4iv—Cs—S2vi117.055 (5)S3vi—Cs—S3v92.710 (14)
S2v—Cs—S2vi100.933 (7)S3—Cs—S3v92.710 (14)
S2—Cs—S2vi100.933 (7)
Symmetry codes: (i) y+1, x, z+1/2; (ii) xy1, y2, z+1/2; (iii) x1, x+y, z+1/2; (iv) x1/3, y2/3, z+1/3; (v) y1, xy1, z; (vi) x+y, x1, z; (vii) xy, y1, z+1/2; (viii) y, xy, z; (ix) x+y, x, z; (x) x+1, y+1, z; (xi) x+y+1, x, z; (xii) xy, y, z+1/2; (xiii) x, x+y, z+1/2; (xiv) x2/3, xy4/3, z+1/6; (xv) y, x1, z+1/2; (xvi) xy1, y1, z+1/2; (xvii) y+1/3, x+y1/3, z+2/3; (xviii) xy2/3, x1/3, z+2/3.

Experimental details

Crystal data
Chemical formulaCs2Mo15S19
Mr2314.06
Crystal system, space groupHexagonal, R3c
Temperature (K)293
a, c (Å)9.5012 (1), 56.4199 (6)
V3)4410.82 (8)
Z6
Radiation typeMo Kα
µ (mm1)9.94
Crystal size (mm)0.34 × 0.25 × 0.21
Data collection
DiffractometerNonius KappaCCD area-detector
diffractometer
Absorption correctionAnalytical
(de Meulenaar & Tompa, 1965)
Tmin, Tmax0.098, 0.203
No. of measured, independent and
observed [I > 2σ(I)] reflections
33032, 3042, 2575
Rint0.067
(sin θ/λ)max1)0.903
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.030, 0.062, 1.16
No. of reflections3042
No. of parameters57
w = 1/[σ2(Fo2) + (0.0187P)2 + 51.7289P]
where P = (Fo2 + 2Fc2)/3
Δρmax, Δρmin (e Å3)2.99, 1.98

Computer programs: COLLECT (Nonius, 1998), COLLECT, EVALCCD (Duisenberg, 1998), Please provide missing details, SHELXL97 (Sheldrick, 1997), DIAMOND (Bergerhoff, 1996), WinGX (Farrugia, 1999).

Selected bond lengths (Å) top
Cs—S1i3.2825 (6)Mo1—Mo22.7271 (2)
Cs—S1ii3.2825 (6)Mo1—Mo2ix2.7826 (2)
Cs—S1iii3.2825 (6)Mo2—S1x2.3977 (6)
Cs—S53.4080 (11)Mo2—S1vii2.3977 (6)
Cs—S4iv3.5640 (11)Mo2—S2v2.4721 (7)
Cs—S2v3.7465 (5)Mo2—S2xi2.4721 (7)
Cs—S23.7465 (5)Mo2—Mo2ix2.6893 (5)
Cs—S2vi3.7465 (5)Mo2—Mo2viii2.6893 (5)
Cs—S3vi3.7497 (6)Mo3—S52.4170 (8)
Cs—S33.7497 (6)Mo3—S12.4429 (6)
Cs—S3v3.7497 (6)Mo3—S3xii2.4481 (6)
Mo1—S42.4189 (8)Mo3—S3xiii2.4703 (6)
Mo1—S1iii2.4328 (6)Mo3—S3xiv2.4725 (6)
Mo1—S1vii2.4554 (7)Mo3—Mo3v2.6854 (4)
Mo1—S32.5130 (6)Mo3—Mo3vi2.6854 (4)
Mo1—S2v2.6240 (5)Mo3—Mo3xv2.7629 (3)
Mo1—Mo1viii2.6823 (3)Mo3—Mo3xvi2.7629 (3)
Mo1—Mo1ix2.6823 (3)
Symmetry codes: (i) y+1, x, z+1/2; (ii) xy1, y2, z+1/2; (iii) x1, x+y, z+1/2; (iv) x1/3, y2/3, z+1/3; (v) y1, xy1, z; (vi) x+y, x1, z; (vii) xy, y1, z+1/2; (viii) y, xy, z; (ix) x+y, x, z; (x) x+1, y+1, z; (xi) x+y+1, x, z; (xii) x2/3, xy4/3, z+1/6; (xiii) y, x1, z+1/2; (xiv) xy1, y1, z+1/2; (xv) y+1/3, x+y1/3, z+2/3; (xvi) xy2/3, x1/3, z+2/3.
 

Follow Acta Cryst. C
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds