Crystal structure of hexa-kis-(dimethyl sulfoxide-κO)manganese(II) tetra-iodide.

The title salt, [Mn(C2H6OS)6]I4, is made up from discrete [Mn(DMSO)6]2+ (DMSO is dimethyl sulfoxide) units connected through non-classical hydrogen bonds to linear I42- tetra-iodide anions. The MnII ion in the cation, situated on a position with site symmetry -3., is octa-hedrally coordinated by O atoms of the DMSO mol-ecule with an Mn-O distance of 2.1808 (12) Å. The I42- anion contains a neutral I2 mol-ecule weakly coordinated by two iodide ions, forming a linear centrosymmetric tetra-iodide anion. The title compound is isotypic with the Co, Ni, Cu, and Zn analogues.

Chemical context

Inorganic–organic hybrid compounds have attracted significant attention owing to their fascinating structural, optical and electrical properties (Stranks & Snaith, 2015 ▸). In particular, CH3NH3PbX 3 hybrids obtained from PbX 2 and CH3NH3 X (X = I, Br, Cl) are inter­esting due to their high absorption coefficient and applications in optoelectronics (Stoumpos & Kanatzidis, 2015 ▸). In general, this family of materials adopts the perovskite ABX 3 structure type, where A is an organic cation, which is surrounded by twelve nearest X halide anions, and B is a metal cation (Grätzel, 2014 ▸). There are continuous efforts on replacing Pb in these hybrids due to its toxicity (Wang et al., 2015 ▸). In the present work, one such attempt was made to produce a hybrid between CH3NH3I and MnI2. However, we obtained instead the title salt [Mn(DMSO)6]I4 (DMSO is dimethyl sulfoxide), and report here its crystal structure.

Structural commentary

The title salt is the first compound with a [Mn(DMSO]2+ cation and a linear tetra­iodide anion. The Mn2+ cation is bound to the O atoms of six DMSO mol­ecules arranged in an octa­hedral configuration (Fig. 1 ▸). Owing to the . site symmetry of the metal cation, the deviations of corresponding angles from ideal values are minute [range cis O—Mn—O angles 86.28 (4)–93.73 (4)°; all trans angles 180°]. The Mn—O bond length is 2.1808 (12) Å. The four I atoms are arranged in a linear fashion. The bond length between the two central I atoms is 2.8460 (5) Å; this inner I2 moiety is rather weakly bonded to two terminal I− anions with a bond lengths of 3.3251 (6) Å. This confirms the existence of a linear, centrosymmetric polyiodide ion I4 2−, consistent with previous reports (Long et al., 1999 ▸). Both inner and terminal bond lengths of the I4 2− anion are comparable with values found in [Cu(NH3)4]I4 (Dubler & Linowsky, 1975 ▸) or other [M(DMSO)6]I4 compounds (Long et al., 1999 ▸; Tkachev et al., 1994 ▸; Garzón-Tovar et al., 2013a ▸,b ▸).

Figure 1

The mol­ecular components of the title compound, with displacement ellipsoids drawn at the 50% probability level. H atoms have been omitted for clarity. [Symmetry code: (′)  − x,  − y,  − z.]

Supra­molecular features

Fig. 2 ▸ shows the unit-cell projection along [001]. The hexa­gonal rod packing of isolated [Mn(DMSO)6]2+ mol­ecules can be seen along [211]. The tetra­iodide counter-anions are located between the rows (Fig. 3 ▸). An extended three-dimensional supra­molecular network is accomplished through non-classical hydrogen bonding between H atoms of the DMSO mol­ecules and the linear I4 2− polyiodide anions. Table 1 ▸ collates numerical details of these C—H⋯I inter­actions.

Figure 2

The unit cell of [Mn(DMSO)6]I4 in a view approximately along [001]. H atoms have been omitted for clarity.

Figure 3

Packing diagram of the title compound. Non-classical hydrogen bonds are shown as dashed lines.

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C1—H1A⋯I2	0.98	3.10	3.954 (2)	147
C2—H2B⋯I1i	0.98	3.26	4.182 (2)	158
C2—H2C⋯I2ii	0.98	3.20	4.108 (2)	154

Symmetry codes: (i) ; (ii) .

Database survey

A number of transition metals have been reported to form complexes with DMSO (Meek et al., 1960 ▸). However, reports on Mn complexes of DMSO with halide anions are scarce, as revealed by a search in the Cambridge Structural Database (Groom et al. 2016 ▸). Recently Glatz et al. (2016 ▸) reported the crystal structure of [Mn(DMSO)6]I2. In particular, polyiodide salts are inter­esting compounds owing to their high conductivity and non-linear properties that are predominantly observed in sulfur-rich compounds (Long et al., 1999 ▸). The structure of the title compound is isotypic with the Co, Ni, Cu, and Zn analogues: [Co(DMSO)6]I4 (Tkachev et al., 1994 ▸), [Ni(DMSO)6]I4 (Long et al., 1999 ▸), [Cu(DMSO)6]I4 (Garzón-Tovar et al., 2013a ▸), [Zn(DMSO)6]I4 (Garzón-Tovar et al., 2013b ▸).

Synthesis and crystallization

The title manganese salt was formed in the course of the targeted synthesis of a hybrid compound between CH3NH3I and MnI2. Anhydrous MnI2 and dimethyl sulfoxide (DMSO) were purchased from Alfa–Aesar and Sigma–Aldrich, respectively. CH3NH3I was purchased from Dyesol. The precursors were used without further purification. The title manganese salt was synthesized by adding anhydrous MnI2 (308.7 mg) and CH3NH3I (158.9 mg) in a glass vial. Then 2 ml DMSO was added to the vial (capped afterwards) and stirred at 353 K for 24 h inside a nitro­gen glove box. A reddish-black solution was observed after 24 h which was cooled down to room temperature and left for 7 d undisturbed. Single crystals of the title compound were obtained as the only solid product after 7 d. The crystals were removed from the vial and dried under nitro­gen flow.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2 ▸. The methyl H atoms were treated as riding and U iso(H) values set at 1.5U eq(C).

Table 2

Experimental details

Crystal data
Chemical formula	[Mn(C2H6OS)6]I4
M r	1031.31
Crystal system, space group	Trigonal, R
Temperature (K)	200
a, c (Å)	11.8702 (10), 19.3860 (18)
V (Å3)	2365.6 (5)
Z	3
Radiation type	Mo Kα
μ (mm−1)	4.75
Crystal size (mm)	0.16 × 0.12 × 0.05
Data collection
Diffractometer	Stoe IPDS2
Absorption correction	Numerical (X-RED32; Stoe & Cie, 2013 ▸)
T min, T max	0.415, 0.615
No. of measured, independent and observed [I > 2σ(I)] reflections	7644, 1417, 1301
R int	0.045
(sin θ/λ)max (Å−1)	0.685
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.017, 0.038, 1.06
No. of reflections	1417
No. of parameters	47
H-atom treatment	H-atom parameters constrained
Δρmax, Δρmin (e Å−3)	0.34, −0.93

Computer programs: X-AREA and X-RED32 (Stoe & Cie, 2013 ▸), SHELXT (Sheldrick, 2015a ▸), SHELXL2014 (Sheldrick, 2015b ▸), DIAMOND (Brandenburg, 2006 ▸) and publCIF (Westrip, 2010 ▸).

Crystal structure: contains datablock(s) I. DOI: 10.1107/S2056989016017904/wm5337sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989016017904/wm5337Isup2.hkl

CCDC reference: 1515632

Additional supporting information: crystallographic information; 3D view; checkCIF report

[Mn(C2H6OS)6]I4	Dx = 2.172 Mg m−3
Mr = 1031.31	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3:H	Cell parameters from 10442 reflections
a = 11.8702 (10) Å	θ = 2.2–29.5°
c = 19.3860 (18) Å	µ = 4.75 mm−1
V = 2365.6 (5) Å3	T = 200 K
Z = 3	Block, brown
F(000) = 1467	0.16 × 0.12 × 0.05 mm

Stoe IPDS-2 diffractometer	1417 independent reflections
Radiation source: sealed X-ray tube, 12 x 0.4 mm long-fine focus	1301 reflections with I > 2σ(I)
Detector resolution: 6.67 pixels mm-1	Rint = 0.045
rotation method scans	θmax = 29.2°, θmin = 2.2°
Absorption correction: numerical (X-RED32; Stoe & Cie, 2013)	h = −16→16
Tmin = 0.415, Tmax = 0.615	k = −16→16
7644 measured reflections	l = −26→26

Refinement on F2	0 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.017	H-atom parameters constrained
wR(F2) = 0.038	w = 1/[σ2(Fo2) + (0.0105P)2 + 3.7009P] where P = (Fo2 + 2Fc2)/3
S = 1.06	(Δ/σ)max = 0.001
1417 reflections	Δρmax = 0.34 e Å−3
47 parameters	Δρmin = −0.93 e Å−3

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

	x	y	z	Uiso*/Ueq
Mn1	0.3333	0.6667	0.6667	0.01931 (12)
I1	0.6667	0.3333	0.75993 (2)	0.03170 (6)
I2	0.6667	0.3333	0.58841 (2)	0.03067 (6)
S1	0.54925 (4)	0.62436 (4)	0.58993 (2)	0.02341 (9)
O1	0.50872 (12)	0.72442 (12)	0.60608 (6)	0.0247 (2)
C1	0.67639 (18)	0.65612 (19)	0.64912 (11)	0.0325 (4)
H1A	0.7149	0.6023	0.6373	0.049*
H1B	0.6410	0.6353	0.6960	0.049*
H1C	0.7433	0.7482	0.6466	0.049*
C2	0.64415 (19)	0.6821 (2)	0.51353 (10)	0.0343 (4)
H2A	0.6785	0.6249	0.5015	0.051*
H2B	0.7165	0.7706	0.5212	0.051*
H2C	0.5897	0.6829	0.4757	0.051*

	U11	U22	U33	U12	U13	U23
Mn1	0.01701 (16)	0.01701 (16)	0.0239 (3)	0.00851 (8)	0.000	0.000
I1	0.02446 (7)	0.02446 (7)	0.04619 (13)	0.01223 (4)	0.000	0.000
I2	0.03185 (8)	0.03185 (8)	0.02833 (10)	0.01592 (4)	0.000	0.000
S1	0.01918 (17)	0.02122 (18)	0.0279 (2)	0.00868 (15)	0.00044 (15)	−0.00439 (15)
O1	0.0219 (5)	0.0245 (6)	0.0294 (6)	0.0128 (5)	0.0038 (5)	0.0002 (5)
C1	0.0318 (9)	0.0368 (10)	0.0344 (9)	0.0212 (8)	−0.0054 (8)	−0.0033 (8)
C2	0.0298 (9)	0.0447 (11)	0.0283 (9)	0.0185 (9)	0.0040 (7)	−0.0047 (8)

Mn1—O1i	2.1808 (12)	S1—C2	1.778 (2)
Mn1—O1ii	2.1808 (12)	S1—C1	1.7798 (19)
Mn1—O1iii	2.1808 (12)	C1—H1A	0.9800
Mn1—O1iv	2.1808 (12)	C1—H1B	0.9800
Mn1—O1v	2.1809 (12)	C1—H1C	0.9800
Mn1—O1	2.1808 (12)	C2—H2A	0.9800
I1—I1vi	2.8460 (5)	C2—H2B	0.9800
S1—O1	1.5204 (12)	C2—H2C	0.9800
O1i—Mn1—O1ii	180.00 (6)	O1—S1—C1	105.53 (9)
O1i—Mn1—O1iii	86.27 (4)	C2—S1—C1	98.56 (10)
O1ii—Mn1—O1iii	93.73 (4)	S1—O1—Mn1	119.38 (7)
O1i—Mn1—O1iv	93.73 (4)	S1—C1—H1A	109.5
O1ii—Mn1—O1iv	86.27 (4)	S1—C1—H1B	109.5
O1iii—Mn1—O1iv	180.00 (5)	H1A—C1—H1B	109.5
O1i—Mn1—O1v	93.73 (4)	S1—C1—H1C	109.5
O1ii—Mn1—O1v	86.27 (4)	H1A—C1—H1C	109.5
O1iii—Mn1—O1v	86.27 (5)	H1B—C1—H1C	109.5
O1iv—Mn1—O1v	93.72 (4)	S1—C2—H2A	109.5
O1i—Mn1—O1	86.28 (4)	S1—C2—H2B	109.5
O1ii—Mn1—O1	93.73 (4)	H2A—C2—H2B	109.5
O1iii—Mn1—O1	93.73 (4)	S1—C2—H2C	109.5
O1iv—Mn1—O1	86.27 (5)	H2A—C2—H2C	109.5
O1v—Mn1—O1	180.0	H2B—C2—H2C	109.5
O1—S1—C2	104.90 (9)

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1A···I2	0.98	3.10	3.954 (2)	147
C2—H2B···I1vii	0.98	3.26	4.182 (2)	158
C2—H2C···I2viii	0.98	3.20	4.108 (2)	154