Two-dimensional polymeric [Hg₄(μ₂-I)₆I₂(μ₂-C₄S₆)]_n

The title compound, poly[(μ₂-2H,5H-1,3-dithiolo[4,5-d][1,3]di­thiole-2,5-dithione)hexa-μ₂-iodido-diiodidotetra­mercury(II)], [Hg₄I₈(C₄S₆)]_n, represents the first example of a coordination polymer assembled by the α,α-C₄S₆ dithione ligand. The Hg^II ions are four-coordinated in a distorted tetra­hedral geometry, the coordination demand being satisfied either by four bridging iodide ligands or by three iodide ligands (one terminal and two bridging) and a thio­carbonyl S atom. Due to the bridging nature of the dithione ligand, the coordination polymer has a two-dimensional structure, built up of undulated layers parallel to (001). There is an inversion center at the mid-point of the central C=C double bond.

Related literature

For the synthesis and structure of the α,α-C₄S₆ ligand, see: Krug et al. (1977); Beck et al. (2006). For related studies on polymeric binary carbon sulfides, see: Galloway et al. (1994). For the synthesis and structures of coordination polymers with sulfur-rich ligands, see: Peindy et al. (2005); Hameau et al. (2006); Ndiaye et al. (2007); Guyon et al. (2008).

Experimental

Crystal data

• [Hg₄I₈(C₄S₆)]

• M_r = 1028.98

• Monoclinic, P 2₁ /c

• a = 8.5502 (6) Å

• b = 11.2156 (8) Å

• c = 13.4634 (9) Å

• β = 91.343 (1)°

• V = 1290.73 (16) ų

• Z = 4

• Mo Kα radiation

• μ = 33.76 mm⁻¹

• T = 173 K

• 0.30 × 0.10 × 0.10 mm

Data collection

• Bruker APEX CCD diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 1999) T_min = 0.035, T_max = 0.133

• 24415 measured reflections

• 2543 independent reflections

• 2337 reflections with I > 2σ(I)

• R_int = 0.086

Refinement

• R[F² > 2σ(F²)] = 0.039

• wR(F²) = 0.114

• S = 1.03

• 2543 reflections

• 100 parameters

• Δρ_max = 3.56 e Å⁻³

• Δρ_min = −3.29 e Å⁻³

Data collection: SMART (Bruker, 2001); cell refinement: SAINT-Plus (Bruker, 1999); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

Supporting information

S1. Comment

Molecular and polymeric binary carbon sulfides have been the subject of numerous studies (see for example Galloway et al., 1994). In the context of our interest in using sulfur-rich ligands to synthesize coordination polymers (Peindy et al., 2005; Hameau et al., 2006; Ndiaye et al. 2007; Guyon et al. 2008), carbon sulfides and especially 1,3-dithiolo-(4,5-d)-1,3-dithiol-2,5-dithione (α,α-C₄S₆) appears attractive due to the presence of two potentially coordinating thiocarbonyl sulfur atoms. The α,α-C₄S₆ carbon sulfide compound, first prepared in 1977 (Krug et al., 1977), reacts with HgI₂ to afford the coordination polymer [Hg₄I₈(C₄S₆)]_n (1). As shown in Fig.1, the monomeric unit has a centrosymmetrical tetranuclear structure which is formed by one α,α-C₄S₆ ligand linking two Hg₂I₄ fragments with an inversion centre located at the mid-point of the central C═C bond. Each mercury(II) centre is arranged in a distorted tetrahedral manner. The Hg1 atom is coordinated by one terminal iodine atom (I1), two bridging iodine atoms (I2 and I4ⁱⁱⁱ) and the sulfur of the thiocarbonyl function S2 whereas the coordination sphere of Hg2 involves only bridging iodo ligands (I2, I3, I3ⁱⁱ and I4). Note however that the bridging contribution of I4 is weak since the Hg1ⁱⁱⁱ-I4 distance (3.423 (1) Å) is quite long compared to that of Hg2—I4 (2.6497 (8) Å). The C═S bond of α,α-C₄S₆ is weakly affected by coordination of the sulfur atom on Hg1 (1.671 (10) Å versus 1.645 (2) in the free ligand, Beck et al., 2006). The Hg1—S2 distance of 2.697 (3) Å is somewhat longer than that reported for 4,5-bis(methylthio)-1,3-dithiole-2-thione on HgI₂ (Hameau et al., 2006). The α,α-C₄S₆ ligands connect the inorganic chains built upon the alternance of 8-membered Hg₄I₄ and 4-membered Hg₂I₂ cycles to form a two-dimensional framework. Note that there are no S—S interactions inferior to the sum of the van der Waals radii of two S atoms in the solid state.

Related literature

For the synthesis and structure of the α,α-C₄S₆ ligand, see: Krug et al. (1977); Beck et al. (2006). For related studies on polymeric binary carbon sulfides, see: Galloway et al. (1994). For the synthesis and structures of coordination polymers with sulfur-rich ligands, see: Peindy et al. (2005); Hameau et al. (2006); Ndiaye et al. (2007); Guyon et al. (2008).

S2. Experimental

The α,α-C₄S₆ ligand was prepared as described previously (Beck et al., 2006). To the α,α-C₄S₆ dithione (14 mg, 58 µmol) dissolved in 13.5 ml of a solvent mixture (toluene/acetonitrile/chlorobenzene in 2/1/1 ratio) was added upon stirring a solution of HgI₂ (53 mg, 116 µmol) in toluene (10 ml). The resulting solution was refluxed for 0.2 h., then allowed to reach room temperature and filtered. Dark red crystals suitable for X-ray analysis were obtained by slow evaporation of the solution (yield 85%). IR (KBr): ν _C═S = 1036 cm^-1.

S3. Refinement

The largest Fourier peak/hole (3.56 and –3.29 e/ų, respectively) are found 0.95 and 0.68Å from Hg1 (see even extra table).

Computing details

Data collection: SMART (Bruker, 2001); cell refinement: SAINT-Plus (Bruker, 1999); data reduction: SAINT-Plus (Bruker, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

Fig. 1. A view of the title compound along (001). Displacement ellipsoids are drawn at the 50% probability level. Symmetry operations: (i) -x, -y+2, -z+2; (ii) -x, -y+1, -z+2; (iii) -x+1, -y+1, -z+2.

Poly[(µ₂-2H,5H-1,3-dithiolo[4,5-d][1,3]dithiole- 2,5-dithione)hexa-µ₂-iodido-diiodidotetramercury(II)]

Crystal data

[Hg4I8(C4S6)]	F(000) = 1728
Mr = 1028.98	Dx = 5.295 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 8987 reflections
a = 8.5502 (6) Å	θ = 2.4–26°
b = 11.2156 (8) Å	µ = 33.76 mm^−1
c = 13.4634 (9) Å	T = 173 K
β = 91.343 (1)°	Needle, dark red
V = 1290.73 (16) Å^3	0.30 × 0.10 × 0.10 mm
Z = 4

Data collection

Bruker APEX CCD diffractometer	2543 independent reflections
Radiation source: fine-focus sealed tube	2337 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.086
ω scans	θmax = 26.0°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Bruker, 1999)	h = −10→10
Tmin = 0.035, Tmax = 0.133	k = −13→13
24415 measured reflections	l = −16→16

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	Primary atom site location: structure-invariant direct methods
R[F^2 > 2σ(F^2)] = 0.039	Secondary atom site location: difference Fourier map
wR(F^2) = 0.114	w = 1/[σ^2(Fo^2) + (0.077P)^2 + 7.1937P] where P = (Fo^2 + 2Fc^2)/3
S = 1.03	(Δ/σ)max = 0.001
2543 reflections	Δρmax = 3.56 e Å^−3
100 parameters	Δρmin = −3.29 e Å^−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
C1	0.0263 (12)	0.9542 (9)	1.0288 (7)	0.029 (2)
C2	0.2439 (12)	0.9942 (9)	0.9076 (8)	0.033 (2)
Hg1	0.51629 (6)	0.77041 (5)	0.83365 (5)	0.05585 (19)
Hg2	0.22624 (7)	0.46970 (6)	0.97826 (5)	0.0672 (2)
I1	0.82359 (9)	0.77867 (6)	0.83985 (5)	0.0374 (2)
I2	0.25603 (8)	0.64475 (6)	0.79810 (5)	0.0372 (2)
I3	0.08558 (9)	0.60123 (6)	1.11662 (5)	0.03616 (19)
I4	0.45656 (8)	0.32667 (6)	0.92556 (5)	0.03444 (19)
S1	0.2076 (3)	0.8973 (2)	1.0033 (2)	0.0374 (6)
S2	0.4123 (3)	0.9968 (3)	0.8465 (2)	0.0427 (6)
S3	−0.0987 (3)	0.9043 (2)	1.1185 (2)	0.0363 (6)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.025 (5)	0.035 (5)	0.028 (5)	−0.001 (4)	0.003 (4)	0.002 (4)
C2	0.031 (5)	0.029 (5)	0.039 (5)	−0.002 (4)	0.003 (4)	−0.001 (4)
Hg1	0.0325 (3)	0.0672 (4)	0.0682 (4)	−0.0029 (2)	0.0078 (2)	0.0044 (3)
Hg2	0.0477 (4)	0.0668 (4)	0.0881 (5)	0.0157 (3)	0.0243 (3)	−0.0110 (3)
I1	0.0303 (4)	0.0452 (4)	0.0369 (4)	−0.0012 (3)	0.0048 (3)	−0.0032 (3)
I2	0.0332 (4)	0.0424 (4)	0.0359 (4)	−0.0019 (3)	0.0013 (3)	0.0038 (3)
I3	0.0351 (4)	0.0365 (4)	0.0369 (4)	−0.0014 (3)	0.0029 (3)	−0.0047 (3)
I4	0.0305 (4)	0.0404 (4)	0.0326 (4)	0.0048 (3)	0.0041 (3)	−0.0024 (3)
S1	0.0310 (14)	0.0406 (14)	0.0410 (14)	0.0074 (11)	0.0101 (11)	0.0073 (11)
S2	0.0350 (15)	0.0365 (13)	0.0576 (17)	0.0020 (11)	0.0205 (13)	0.0038 (12)
S3	0.0339 (14)	0.0372 (13)	0.0383 (13)	0.0051 (10)	0.0128 (11)	0.0067 (11)

Geometric parameters (Å, º)

C1—C1^i	1.36 (2)	Hg1—S2	2.697 (3)
C1—S1	1.718 (11)	Hg2—I4	2.6496 (9)
C1—S3	1.724 (11)	Hg2—I3	2.6828 (9)
C2—S2	1.675 (11)	Hg2—I3^ii	3.0353 (10)
C2—S3^i	1.715 (11)	Hg2—I2	3.1357 (10)
C2—S1	1.720 (11)	I3—Hg2^ii	3.0353 (10)
Hg1—I1	2.6285 (9)	S3—C2^i	1.715 (11)
Hg1—I2	2.6678 (9)
C1^i—C1—S1	117.1 (11)	I4—Hg2—I3^ii	112.31 (3)
C1^i—C1—S3	116.3 (11)	I3—Hg2—I3^ii	91.87 (3)
S1—C1—S3	126.6 (6)	I4—Hg2—I2	95.60 (3)
S2—C2—S3^i	121.0 (6)	I3—Hg2—I2	103.81 (3)
S2—C2—S1	123.4 (6)	I3^ii—Hg2—I2	85.70 (3)
S3^i—C2—S1	115.5 (6)	Hg1—I2—Hg2	105.93 (3)
I1—Hg1—I2	148.57 (3)	Hg2—I3—Hg2^ii	88.13 (3)
I1—Hg1—S2	107.19 (7)	C1—S1—C2	95.4 (5)
I2—Hg1—S2	103.53 (7)	C2—S2—Hg1	107.7 (4)
I4—Hg2—I3	150.11 (4)	C2^i—S3—C1	95.7 (5)

Symmetry codes: (i) −x, −y+2, −z+2; (ii) −x, −y+1, −z+2.