Bis(pyrrolidinium) hexa­chlorido­stannate: a redetermination

Gotoh, K.; Ishida, H.

doi:10.1107/S2414314618013974

metal-organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 3| Part 10| October 2018| x181397

https://doi.org/10.1107/S2414314618013974

Open

access

Bis(pyrrolidinium) hexachloridostannate: a redetermination

Kazuma Gotoh ^a and Hiroyuki Ishida ^a ^*

^aDepartment of Chemistry, Faculty of Science, Okayama University, Okayama 700-8530, Japan
^*Correspondence e-mail: ishidah@cc.okayama-u.ac.jp

Edited by H. Stoeckli-Evans, University of Neuchâtel, Switzerland (Received 28 September 2018; accepted 2 October 2018; online 19 October 2018)

The crystal structure of the title compound, (C₄H₁₀N)₂[SnCl₆], has been redetermined at 180 K. All atoms were located with higher precision than the previous structure determined at room temperature [Ishida et al. (2000 ). J Mol. Struct. 524, 95–103]. In the crystal, the Sn^IV atom is located on a special position of site symmetry 2/m and is coordinated by six Cl atoms in a pseudo-octahedral geometry. Of the six Cl atoms, two equivalent axial atoms lie on the mirror plane [Sn—Cl = 2.4281 (6) Å] and the other four equivalent equatorial atoms lie on general positions [Sn—Cl = 2.4285 (4) Å]. The N atom of the pyrrolidinium cation lies on a mirror plane and the other atoms of the cation are disordered over two sites with respect to the mirror plane. Each component of the disordered five-membered rings adopts a twist conformation. The cations and anions are connected via N—H⋯Cl hydrogen bonds, forming a tape-like structure propagating along [010].

Keywords: crystal structure; pyrolidinium; hexachlorostannate; ring conformation; disorder.

CCDC reference: 1871008

Structure description

Previously, we have reported structural phase transitions of three bis(pyrrolidinium) hexachlorometalates, namely, 2C₄H₈NH₂⁺·MCl₆²⁻ (M = Sn, Te, Pt), by using ³⁵Cl nuclear quadrupole resonance (NQR) and differential scanning calorimetry (DSC). The transitions occur at 150, 159 and 134 K for the stannate, tellurate and platinate, respectively, and their crystal structures at room temperature have been determined by single-crystal X-ray diffraction (Ishida et al., 2000). They are isotypic with each other, belonging to the space group C2/m. The pyrrolidinium cation in these crystals are expected to be rather freely packed because of the large free volume created by the bulky MCl₆²⁻ anion. The ring conformation of the pseudo-free cation was, however, not determined precisely at room temperature owing to large thermal motion, including disordering of the cation. In the present study, we have redetermined the crystal structure of the title compound at a low temperature (180 K) in the high-temperature phase, in order to obtain precise information on the conformation of the cation and intermolecular interactions in the crystal.

A search of the Cambridge Structural Database (Version 5.39, last update August 2018; Groom et al., 2016 ) gave 72 hits for salts of pyrrolidinium ion. The salt of the pyrrolidinium ion with a discrete MX₆ type anion (M = metal X= halogen) other than 2C₄H₁₀N⁺·MCl₆²⁻ (M = Sn, Te, Pt) was reported for C₄H₁₀N⁺·SbCl₆⁻ (Jakubas et al., 2005 ), in which the cation ring adopts a twist form at 300 K (CSD refcode XAKWEM) but a flat form at 340 K (XAKWEM01) probably due to an averaging of the disordered ring. Although the pyrrolidinium ion is stable in the twist on C2–C3 form in an isolated system (Ishida, 2000 ), different conformations of the cation are observed in crystals, for example, an N-envelope conformation in C₄H₁₀N⁺·Cl⁻ (EHACUM; Giglmeier et al., 2009 ) and C-envelope conformations in C₁₈H₁₆OSi·C₄H₁₀N⁺·C₂H₃O₂⁻ (AJIHUY; Bauer & Strohmann, 2015 ) and C₄H₁₀N⁺·C₆BrF₄O⁻ (BIYFUM; Takemura et al., 2014 ).

In the title compound, Fig. 1, the Sn^IV atom in the SnCl₆²⁻ anion is located on a special position of site symmetry 2/m and is coordinated by six Cl atoms in a pseudo-octahedral geometry. Of the six Cl atoms, two Cl atoms (Cl1 and Cl2) are crystallographically independent; two equivalent axial Cl atoms lie on a mirror plane and four equivalent equatorial Cl atoms lie on general positions. The Sn—Cl bond lengths are experimentally equivalent [Sn1—Cl1 = 2.4281 (6) Å and Sn1—Cl2 = 2.4285 (4) Å]. The N atom of the pyrrolidinium cation lies on a mirror plane and the other atoms of the cation are disordered over two sites about the mirror plane with an occupancy ratio of 0.5:0.5. The puckering parameters [q₂ = 0.424 (11) Å and φ₂ = 89.2 (19)°] and the torsion angles of the five-membered ring show that the cation adopts a conformation close to the twist on C2—C3 form, as expected from the theoretical calculations for an isolated cation (Ishida, 2000).

Figure 1
The molecular structure of the title compound, showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. The N—H⋯Cl hydrogen bond is shown as a dashed line (Table 1

). Only one component is shown for the disordered cation. [Symmetry codes: (iii) x, −y + 1, z; (iv) −x + 1, −y + 1, −z; (v) −x + 1, y, −z.]

In the crystal, the NH₂ group of the cation is hydrogen-bonded to the equatorial Cl atoms of the neighbouring anions (N1—H1NA⋯Cl2, N1—H1NB⋯Cl2ⁱ and N1—H1NB⋯Cl2ⁱⁱ; symmetry codes as in Table 1), forming a tape-like structure along the b-axis direction (Fig. 2). The anion is surrounded by six cations, four of which are linked to the anions via the N—H⋯Cl hydrogen bonds (Fig. 3).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1NA⋯Cl2	0.88 (5)	2.54 (5)	3.365 (2)	156 (5)
N1—H1NB⋯Cl2ⁱ	0.89 (4)	2.81 (6)	3.472 (2)	133 (5)
N1—H1NB⋯Cl2ⁱⁱ	0.89 (4)	2.77 (5)	3.365 (2)	126 (4)
Symmetry codes: (i) -x+1, -y, -z; (ii) x, -y, z.

Figure 2
A partial packing diagram of the title compound, showing the tape-like structure formed by N—H⋯Cl hydrogen bonds (dashed lines; see Table 1

). Only one component is shown for the disordered cation. Displacement ellipsoids are drawn at the 50% probability level and H atoms, except those of the NH₂ group, have been omitted. [Symmetry codes: (i) −x + 1, −y, −z; (ii) x, −y, z; (v) −x + 1, y, −z.]

Figure 3
A view along the c axis of the crystal packing of the title compound. The N—H⋯Cl hydrogen bonds (Table 1

) are shown as dashed lines. Only one component of the disordered cation is shown.

Synthesis and crystallization

The title compound was prepared by adding pyrrolidine to a hydrochloric acid solution of SnCl₄ according to the method described previously (Ishida et al., 2000). Single crystals suitable for X-ray diffraction were obtained from a concentrated hydrochloric acid solution.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2.

Table 2
Experimental details

Crystal data
Chemical formula	(C₄H₁₀N)₂[SnCl₆]
M_r	475.67
Crystal system, space group	Monoclinic, C2/m
Temperature (K)	180
a, b, c (Å)	16.3784 (11), 7.3134 (3), 7.1566 (4)
β (°)	91.205 (2)
V (Å³)	857.04 (8)
Z	2
Radiation type	Mo Kα
μ (mm⁻¹)	2.41
Crystal size (mm)	0.20 × 0.20 × 0.10

Data collection
Diffractometer	Rigaku R-AXIS RAPIDII
Absorption correction	Multi-scan (ABSCOR; Higashi, 1995 )
T_min, T_max	0.579, 0.786
No. of measured, independent and observed [I > 2σ(I)] reflections	5281, 1343, 1308
R_int	0.038
(sin θ/λ)_max (Å⁻¹)	0.704

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.024, 0.057, 1.09
No. of reflections	1343
No. of parameters	68
No. of restraints	2
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.54, −1.10
Computer programs: RAPID-AUTO (Rigaku, 2006 ), SHELXT2018/2 (Sheldrick, 2015a ), SHELXL2018/3 (Sheldrick, 2015b ), ORTEP-3 for Windows (Farrugia, 2012 ), CrystalStructure (Rigaku, 2018 ) and PLATON (Spek, 2009 ).

Structural data

CCDC reference: 1871008

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S2414314618013974/su5454sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314618013974/su5454Isup2.hkl

checkCIF report

Computing details top

Data collection: RAPID-AUTO (Rigaku, 2006); cell refinement: RAPID-AUTO (Rigaku, 2006); data reduction: RAPID-AUTO (Rigaku, 2006); program(s) used to solve structure: SHELXT2018/2 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018/3 (Sheldrick, 2015b); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: CrystalStructure (Rigaku, 2018) and PLATON (Spek, 2009).

Bis(pyrrolidinium) hexachloridostannate top

Crystal data top

(C₄H₁₀N)₂[SnCl₆]	F(000) = 468.00
M_r = 475.67	D_x = 1.843 Mg m⁻³
Monoclinic, C2/m	Mo Kα radiation, λ = 0.71075 Å
a = 16.3784 (11) Å	Cell parameters from 5181 reflections
b = 7.3134 (3) Å	θ = 3.1–30.0°
c = 7.1566 (4) Å	µ = 2.41 mm⁻¹
β = 91.205 (2)°	T = 180 K
V = 857.04 (8) Å³	Platelet, colorless
Z = 2	0.20 × 0.20 × 0.10 mm

Data collection top

Rigaku R-AXIS RAPIDII diffractometer	1308 reflections with I > 2σ(I)
Detector resolution: 10.000 pixels mm^-1	R_int = 0.038
ω scans	θ_max = 30.0°, θ_min = 3.1°
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	h = −22→22
T_min = 0.579, T_max = 0.786	k = −10→9
5281 measured reflections	l = −10→10
1343 independent reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.024	Hydrogen site location: mixed
wR(F²) = 0.057	H atoms treated by a mixture of independent and constrained refinement
S = 1.09	w = 1/[σ²(F_o²) + (0.035P)² + 0.3195P] where P = (F_o² + 2F_c²)/3
1343 reflections	(Δ/σ)_max = 0.001
68 parameters	Δρ_max = 0.54 e Å⁻³
2 restraints	Δρ_min = −1.10 e Å⁻³

Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
Sn1	0.500000	0.500000	0.000000	0.02448 (8)
Cl1	0.61941 (4)	0.500000	0.20690 (9)	0.03911 (14)
Cl2	0.56208 (3)	0.26144 (5)	−0.18554 (6)	0.03335 (10)
N1	0.61485 (15)	0.000000	0.1846 (3)	0.0378 (5)
H1NA	0.590 (4)	0.082 (6)	0.113 (7)	0.057*	0.5
H1NB	0.595 (4)	−0.111 (5)	0.163 (7)	0.057*	0.5
C1	0.7040 (2)	−0.015 (5)	0.1454 (6)	0.054 (3)	0.5
H1A	0.718653	−0.141991	0.112102	0.065*	0.5
H1B	0.719081	0.067232	0.041717	0.065*	0.5
C2	0.7455 (2)	0.0412 (6)	0.3229 (7)	0.0512 (12)	0.5
H2A	0.750038	0.175930	0.331790	0.061*	0.5
H2B	0.800714	−0.013262	0.334683	0.061*	0.5
C3	0.6886 (2)	−0.0348 (6)	0.4717 (5)	0.0419 (13)	0.5
H3A	0.694280	−0.169065	0.484205	0.050*	0.5
H3B	0.699197	0.023171	0.594843	0.050*	0.5
C4	0.60557 (18)	0.017 (3)	0.3925 (4)	0.034 (3)	0.5
H4A	0.562866	−0.066758	0.437619	0.041*	0.5
H4B	0.591198	0.143984	0.427417	0.041*	0.5

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Sn1	0.02747 (11)	0.01710 (11)	0.02918 (12)	0.000	0.00770 (7)	0.000
Cl1	0.0362 (3)	0.0386 (3)	0.0423 (3)	0.000	−0.0047 (2)	0.000
Cl2	0.0398 (2)	0.02416 (18)	0.0366 (2)	0.00185 (14)	0.01405 (15)	−0.00506 (14)
N1	0.0375 (11)	0.0426 (12)	0.0334 (10)	0.000	0.0050 (8)	0.000
C1	0.0469 (16)	0.059 (10)	0.0573 (18)	0.002 (4)	0.0289 (14)	−0.009 (6)
C2	0.0279 (14)	0.047 (3)	0.079 (3)	−0.0078 (14)	0.0107 (15)	−0.0076 (19)
C3	0.0323 (14)	0.044 (4)	0.0490 (16)	0.0022 (14)	−0.0033 (12)	0.0092 (16)
C4	0.0279 (11)	0.044 (8)	0.0313 (10)	0.006 (3)	0.0072 (8)	0.004 (2)

Geometric parameters (Å, º) top

Sn1—Cl1ⁱ	2.4281 (6)	C1—H1A	0.9900
Sn1—Cl1	2.4281 (6)	C1—H1B	0.9900
Sn1—Cl2	2.4285 (4)	C2—C3	1.534 (5)
Sn1—Cl2ⁱ	2.4285 (4)	C2—H2A	0.9900
Sn1—Cl2ⁱⁱ	2.4285 (4)	C2—H2B	0.9900
Sn1—Cl2ⁱⁱⁱ	2.4285 (4)	C3—C4	1.512 (8)
N1—C1	1.497 (5)	C3—H3A	0.9900
N1—C4	1.504 (4)	C3—H3B	0.9900
N1—H1NA	0.883 (19)	C4—H4A	0.9900
N1—H1NB	0.89 (2)	C4—H4B	0.9900
C1—C2	1.486 (12)

Cl1ⁱ—Sn1—Cl1	180.0	N1—C1—H1A	110.9
Cl1ⁱ—Sn1—Cl2	90.439 (16)	C2—C1—H1B	110.9
Cl1—Sn1—Cl2	89.560 (16)	N1—C1—H1B	110.9
Cl1ⁱ—Sn1—Cl2ⁱ	89.561 (16)	H1A—C1—H1B	108.9
Cl1—Sn1—Cl2ⁱ	90.440 (16)	C1—C2—C3	102.7 (7)
Cl2—Sn1—Cl2ⁱ	180.000 (18)	C1—C2—H2A	111.2
Cl1ⁱ—Sn1—Cl2ⁱⁱ	89.561 (16)	C3—C2—H2A	111.2
Cl1—Sn1—Cl2ⁱⁱ	90.440 (16)	C1—C2—H2B	111.2
Cl2—Sn1—Cl2ⁱⁱ	88.151 (19)	C3—C2—H2B	111.2
Cl2ⁱ—Sn1—Cl2ⁱⁱ	91.849 (19)	H2A—C2—H2B	109.1
Cl1ⁱ—Sn1—Cl2ⁱⁱⁱ	90.439 (16)	C4—C3—C2	101.7 (5)
Cl1—Sn1—Cl2ⁱⁱⁱ	89.560 (16)	C4—C3—H3A	111.4
Cl2—Sn1—Cl2ⁱⁱⁱ	91.849 (19)	C2—C3—H3A	111.4
Cl2ⁱ—Sn1—Cl2ⁱⁱⁱ	88.151 (19)	C4—C3—H3B	111.4
Cl2ⁱⁱ—Sn1—Cl2ⁱⁱⁱ	180.000 (13)	C2—C3—H3B	111.4
C1—N1—C4	108.1 (3)	H3A—C3—H3B	109.3
C1—N1—H1NA	112 (5)	N1—C4—C3	104.0 (5)
C4—N1—H1NA	118 (4)	N1—C4—H4A	111.0
C1—N1—H1NB	105 (5)	C3—C4—H4A	111.0
C4—N1—H1NB	102 (4)	N1—C4—H4B	111.0
H1NA—N1—H1NB	110 (4)	C3—C4—H4B	111.0
C2—C1—N1	104.5 (7)	H4A—C4—H4B	109.0
C2—C1—H1A	110.9

C4—N1—C1—C2	−14 (2)	C1—N1—C4—C3	−13 (2)
N1—C1—C2—C3	36 (2)	C2—C3—C4—N1	34.7 (13)
C1—C2—C3—C4	−43.9 (15)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1NA···Cl2	0.88 (5)	2.54 (5)	3.365 (2)	156 (5)
N1—H1NB···Cl2^iv	0.89 (4)	2.81 (6)	3.472 (2)	133 (5)
N1—H1NB···Cl2^v	0.89 (4)	2.77 (5)	3.365 (2)	126 (4)

Symmetry codes: (iv) −x+1, −y, −z; (v) x, −y, z.

References

Bauer, J. O. & Strohmann, C. (2015). J. Organomet. Chem. 797, 52–56. CrossRef Google Scholar
Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854. Web of Science CrossRef CAS IUCr Journals Google Scholar
Giglmeier, H., Kerscher, T., Klüfers, P. & Mayer, P. (2009). Acta Cryst. E65, o592. CrossRef IUCr Journals Google Scholar
Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171–179. Web of Science CSD CrossRef IUCr Journals Google Scholar
Higashi, T. (1995). ABSCOR. Rigaku Corporation, Tokyo, Japan. Google Scholar
Ishida, H. (2000). Z. Naturforsch. A: Phys. Sci. 55, 665–666. Google Scholar
Ishida, H., Furukawa, Y., Sato, S. & Kashino, S. (2000). J. Mol. Struct. 524, 95–103. CrossRef Google Scholar
Jakubas, R., Bednarska-Bolek, B., Zaleski, J., Medycki, W., Hołderna-Natkeniec, K., Zieliński, P. & Gałązka, M. (2005). Soild State Sci. 7, 381–390. CrossRef Google Scholar
Rigaku (2006). RAPID-AUTO. Rigaku Corporation, Tokyo, Japan. Google Scholar
Rigaku (2018). CrystalStructure. Rigaku Corporation, Tokyo, Japan. Google Scholar
Sheldrick, G. M. (2015a). Acta Cryst. A71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2015b). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar
Takemura, A., McAllister, L. J., Hart, S., Pridmore, N. E., Karadakov, P. B., Whitwood, A. C. & Bruce, D. W. (2014). Chem. Eur. J. 20, 6721–6732. Web of Science CSD CrossRef CAS PubMed Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.