Guanidinium bromide–18-crown-6 (2/1)

Wang, Y.

doi:10.1107/S1600536812017394

organic compounds

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Volume 68| Part 5| May 2012| Page o1530

doi:10.1107/S1600536812017394

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Guanidinium bromide–18-crown-6 (2/1)

Yu-feng Wang ^a ^*

^aOrdered Matter Science Research Center, Southeast University, Nanjing 211189, People's Republic of China
^*Correspondence e-mail: seuwei@126.com

(Received 13 March 2012; accepted 19 April 2012; online 25 April 2012)

In the title compound, 2CH₆N₃⁺·2Br⁻·C₁₂H₂₄O₆, the 18-crown-6 molecule lies about an inversion center, whereas the guanidinium cation and bromide anion are in general positions. The guanidinium cations link with the bromide anions and the crown ether molecules via N—H⋯O and N—H⋯Br hydrogen bonds, thus forming a three-dimensional network.

Related literature

For applications of crown ethers, see: Clark et al. (1998 ). For ferroelectric metal-organic compounds, see: Fu et al. (2009 , 2011 ); Ye et al. (2006 ); Zhang et al. (2008 , 2010 ). For structures of 18-crown-6 clathrates, see: Zhang & Zhao (2011 ); Ge & Zhao (2010 )

Experimental

Crystal data

2CH₆N₃⁺·2Br⁻·C₁₂H₂₄O₆
M_r = 544.31
Monoclinic, P 2₁ /n
a = 8.9354 (18) Å
b = 9.860 (2) Å
c = 14.306 (3) Å
β = 101.39 (3)°
V = 1235.6 (4) Å³
Z = 2
Mo Kα radiation
μ = 3.32 mm⁻¹
T = 293 K
0.20 × 0.20 × 0.20 mm

Data collection

Rigaku SCXmini diffractometer
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005 ) T_min = 0.936, T_max = 0.937
12464 measured reflections
2835 independent reflections
1968 reflections with I > 2σ(I)
R_int = 0.077

Refinement

R[F² > 2σ(F²)] = 0.053
wR(F²) = 0.127
S = 1.11
2835 reflections
127 parameters
H-atom parameters constrained
Δρ_max = 0.36 e Å⁻³
Δρ_min = −0.79 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1A⋯Br1ⁱ	0.86	2.68	3.470 (3)	154
N1—H1B⋯O2	0.86	2.14	2.938 (4)	155
N2—H2C⋯O2	0.86	2.40	3.127 (5)	143
N2—H2D⋯Br1	0.86	2.82	3.582 (4)	149
N3—H3D⋯Br1	0.86	2.53	3.354 (3)	162
N3—H3C⋯Br1ⁱ	0.86	2.64	3.440 (3)	156
Symmetry code: (i) $[-x+{\script{5\over 2}}, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536812017394/yk2049sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536812017394/yk2049Isup2.hkl

checkCIF report

Comment top

Recent years, crown ethers have attracted much attention because of their wide application in catalysis, solvent extraction, separation of isotopes, host–guest and supramolecular chemistry (Clark et al., 1998). Several 18-crown-6 clathrates were discovered to be dielectric-ferroelectric materials (Fu et al., 2011), hence we designed the title compound in attempts to find new hydrogen-bonded dielectric materials. Dielectric-ferroelectric materials, comprising organic ligands, metal-organic coordination compounds and organic-inorganic hybrids almost show temperature dependence of their dielectric constants (Fu et al., 2009; Zhang et al., 2010; Zhang et al., 2008; Ye et al., 2006). Unfortunately, the study of temperature dependence of dielectric constant of the title compound indicates that the permittivity is basically temperature-independent below its melting point (395K—396K). Herein we descibe the crystal structure of this compound.

At room temperature (25°C), the single-crystal X-ray diffraction reveals that the asymmetric unit of the title compound consists of a guanidinium cation, a bromide anion and a half of 18-crown-6 molecule (Fig. 1). The three NH₂-groups of guanidinium interact with the oxygen atoms of crown ether molecule and with two bromide anions through two N—H···O and N—H···Br hydrogen bonds (Table 1), thus forming a three-dimensional network (Fig. 2).

Related literature top

For applications of crown ethers, see: Clark et al. 1998). For ferroelectric metal-organic compounds, see: Fu et al. (2009, 2011); Ye et al. (2006); Zhang et al. (2008, 2010). For structures of 18-crown-6 clathrates, see: Zhang & Zhao (2011); Ge & Zhao (2010)

Experimental top

The hydrobromic acid (0.81 g, 10 mmol) and guanidinium carbonate (0.9 g, 5 mmol) were dissolved in 30 ml of water and the solution was combined with methanol solution of dibenzo-18-crown-6 (3.6 g 10 mmol). The mixture was stirred for 30 min to complete the reaction, and good quality blocky single crystals were obtained by slow evaporation of the filtrate after two weeks (the chemical yield 72%).

Computing details top

Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear (Rigaku, 2005); data reduction: CrystalClear (Rigaku, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

	Fig. 1. The asymmetric unit of the title compound, showing the atomic numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.
	Fig. 2. A view of the packing of the title compound viewed along the a axis. Dashed lines indicate hydrogen bonds.

Guanidinium bromide–18-crown-6 (2/1) top

Crystal data top

2CH₆N₃⁺·2Br⁻·C₁₂H₂₄O₆	F(000) = 560
M_r = 544.31	D_x = 1.463 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 3638 reflections
a = 8.9354 (18) Å	θ = 3.0–27.5°
b = 9.860 (2) Å	µ = 3.32 mm⁻¹
c = 14.306 (3) Å	T = 293 K
β = 101.39 (3)°	Block, colourless
V = 1235.6 (4) Å³	0.20 × 0.20 × 0.20 mm
Z = 2

Data collection top

Rigaku SCXmini diffractometer	2835 independent reflections
Radiation source: fine-focus sealed tube	1968 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.077
ω scans	θ_max = 27.5°, θ_min = 3.1°
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)	h = −11→11
T_min = 0.936, T_max = 0.937	k = −12→12
12464 measured reflections	l = −18→18

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)] = 0.053	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.127	H-atom parameters constrained
S = 1.11	w = 1/[σ²(F_o²) + (0.0528P)²] where P = (F_o² + 2F_c²)/3
2835 reflections	(Δ/σ)_max = 0.001
127 parameters	Δρ_max = 0.36 e Å⁻³
0 restraints	Δρ_min = −0.79 e Å⁻³

Crystal data top

2CH₆N₃⁺·2Br⁻·C₁₂H₂₄O₆	V = 1235.6 (4) Å³
M_r = 544.31	Z = 2
Monoclinic, P2₁/n	Mo Kα radiation
a = 8.9354 (18) Å	µ = 3.32 mm⁻¹
b = 9.860 (2) Å	T = 293 K
c = 14.306 (3) Å	0.20 × 0.20 × 0.20 mm
β = 101.39 (3)°

Data collection top

Rigaku SCXmini diffractometer	2835 independent reflections
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)	1968 reflections with I > 2σ(I)
T_min = 0.936, T_max = 0.937	R_int = 0.077
12464 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.053	0 restraints
wR(F²) = 0.127	H-atom parameters constrained
S = 1.11	Δρ_max = 0.36 e Å⁻³
2835 reflections	Δρ_min = −0.79 e Å⁻³
127 parameters

Special details top

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

	x	y	z	U_iso*/U_eq
O2	1.1811 (3)	−0.2005 (3)	0.62582 (18)	0.0572 (7)
O3	1.2804 (3)	0.0677 (3)	0.6025 (2)	0.0649 (8)
O1	0.8672 (3)	−0.2293 (3)	0.5560 (2)	0.0759 (9)
C3	1.3789 (5)	−0.0401 (5)	0.6413 (4)	0.0701 (13)
H3A	1.4677	−0.0043	0.6844	0.084*
H3B	1.4135	−0.0887	0.5905	0.084*
C6	0.9606 (6)	−0.3369 (5)	0.5989 (4)	0.0805 (14)
H6A	1.0024	−0.3854	0.5509	0.097*
H6B	0.9004	−0.4000	0.6282	0.097*
C5	1.0855 (6)	−0.2815 (5)	0.6716 (3)	0.0748 (13)
H5A	1.0439	−0.2269	0.7168	0.090*
H5B	1.1441	−0.3549	0.7061	0.090*
C4	1.2942 (5)	−0.1325 (4)	0.6931 (3)	0.0641 (12)
H4A	1.3635	−0.1980	0.7292	0.077*
H4B	1.2465	−0.0814	0.7372	0.077*
C7	0.7498 (6)	−0.2745 (5)	0.4820 (4)	0.0882 (16)
H7A	0.6934	−0.3471	0.5050	0.106*
H7B	0.7932	−0.3093	0.4298	0.106*
C2	1.3526 (5)	0.1611 (6)	0.5511 (4)	0.0848 (15)
H2A	1.3809	0.1160	0.4969	0.102*
H2B	1.4450	0.1949	0.5917	0.102*
N2	1.1162 (4)	−0.1452 (4)	0.4063 (3)	0.0766 (11)
H2C	1.1030	−0.1300	0.4633	0.092*
H2D	1.0709	−0.0954	0.3599	0.092*
Br1	1.01901 (4)	−0.03281 (4)	0.16380 (3)	0.05407 (18)
N3	1.2257 (4)	−0.2677 (4)	0.3022 (2)	0.0643 (9)
H3C	1.2841	−0.3325	0.2911	0.077*
H3D	1.1801	−0.2174	0.2562	0.077*
C1	1.2061 (4)	−0.2453 (4)	0.3900 (3)	0.0508 (9)
N1	1.2761 (4)	−0.3225 (3)	0.4595 (2)	0.0592 (9)
H1A	1.3344	−0.3871	0.4478	0.071*
H1B	1.2638	−0.3085	0.5168	0.071*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O2	0.0681 (18)	0.0558 (17)	0.0495 (15)	0.0000 (13)	0.0161 (13)	−0.0003 (13)
O3	0.0545 (17)	0.078 (2)	0.0651 (19)	−0.0106 (15)	0.0176 (14)	0.0009 (16)
O1	0.082 (2)	0.0625 (19)	0.079 (2)	−0.0205 (16)	0.0071 (17)	0.0001 (17)
C3	0.050 (3)	0.087 (3)	0.073 (3)	0.000 (2)	0.010 (2)	−0.027 (3)
C6	0.100 (4)	0.055 (3)	0.091 (4)	−0.019 (3)	0.032 (3)	0.009 (3)
C5	0.095 (3)	0.065 (3)	0.065 (3)	0.005 (3)	0.018 (3)	0.021 (2)
C4	0.071 (3)	0.067 (3)	0.050 (2)	0.017 (2)	0.002 (2)	−0.010 (2)
C7	0.106 (4)	0.087 (4)	0.068 (3)	−0.055 (3)	0.009 (3)	0.002 (3)
C2	0.060 (3)	0.122 (4)	0.074 (3)	−0.040 (3)	0.015 (2)	0.003 (3)
N2	0.101 (3)	0.074 (2)	0.059 (2)	0.034 (2)	0.026 (2)	0.0060 (19)
Br1	0.0649 (3)	0.0498 (3)	0.0474 (3)	0.00012 (18)	0.01084 (19)	0.00461 (18)
N3	0.070 (2)	0.076 (2)	0.045 (2)	0.0250 (18)	0.0076 (16)	0.0070 (17)
C1	0.050 (2)	0.049 (2)	0.052 (2)	−0.0038 (17)	0.0091 (18)	0.000 (2)
N1	0.075 (2)	0.060 (2)	0.0410 (18)	0.0135 (17)	0.0093 (16)	0.0063 (17)

Geometric parameters (Å, º) top

O2—C4	1.418 (5)	C7—C2ⁱ	1.464 (7)
O2—C5	1.420 (5)	C7—H7A	0.9700
O3—C2	1.411 (5)	C7—H7B	0.9700
O3—C3	1.421 (5)	C2—C7ⁱ	1.464 (7)
O1—C7	1.407 (5)	C2—H2A	0.9700
O1—C6	1.413 (5)	C2—H2B	0.9700
C3—C4	1.474 (6)	N2—C1	1.322 (5)
C3—H3A	0.9700	N2—H2C	0.8600
C3—H3B	0.9700	N2—H2D	0.8600
C6—C5	1.472 (7)	N3—C1	1.320 (5)
C6—H6A	0.9700	N3—H3C	0.8600
C6—H6B	0.9700	N3—H3D	0.8600
C5—H5A	0.9700	C1—N1	1.309 (5)
C5—H5B	0.9700	N1—H1A	0.8600
C4—H4A	0.9700	N1—H1B	0.8600
C4—H4B	0.9700

C4—O2—C5	111.5 (3)	H4A—C4—H4B	108.4
C2—O3—C3	112.3 (4)	O1—C7—C2ⁱ	109.1 (4)
C7—O1—C6	112.1 (4)	O1—C7—H7A	109.9
O3—C3—C4	108.6 (3)	C2ⁱ—C7—H7A	109.9
O3—C3—H3A	110.0	O1—C7—H7B	109.9
C4—C3—H3A	110.0	C2ⁱ—C7—H7B	109.9
O3—C3—H3B	110.0	H7A—C7—H7B	108.3
C4—C3—H3B	110.0	O3—C2—C7ⁱ	110.3 (4)
H3A—C3—H3B	108.4	O3—C2—H2A	109.6
O1—C6—C5	109.2 (4)	C7ⁱ—C2—H2A	109.6
O1—C6—H6A	109.8	O3—C2—H2B	109.6
C5—C6—H6A	109.8	C7ⁱ—C2—H2B	109.6
O1—C6—H6B	109.8	H2A—C2—H2B	108.1
C5—C6—H6B	109.8	C1—N2—H2C	120.0
H6A—C6—H6B	108.3	C1—N2—H2D	120.0
O2—C5—C6	108.9 (4)	H2C—N2—H2D	120.0
O2—C5—H5A	109.9	C1—N3—H3C	120.0
C6—C5—H5A	109.9	C1—N3—H3D	120.0
O2—C5—H5B	109.9	H3C—N3—H3D	120.0
C6—C5—H5B	109.9	N1—C1—N3	119.5 (4)
H5A—C5—H5B	108.3	N1—C1—N2	121.0 (4)
O2—C4—C3	108.6 (3)	N3—C1—N2	119.5 (4)
O2—C4—H4A	110.0	C1—N1—H1A	120.0
C3—C4—H4A	110.0	C1—N1—H1B	120.0
O2—C4—H4B	110.0	H1A—N1—H1B	120.0
C3—C4—H4B	110.0

Symmetry code: (i) −x+2, −y, −z+1.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···Br1ⁱⁱ	0.86	2.68	3.470 (3)	154
N1—H1B···O2	0.86	2.14	2.938 (4)	155
N2—H2C···O2	0.86	2.40	3.127 (5)	143
N2—H2D···Br1	0.86	2.82	3.582 (4)	149
N3—H3D···Br1	0.86	2.53	3.354 (3)	162
N3—H3C···Br1ⁱⁱ	0.86	2.64	3.440 (3)	156

Symmetry code: (ii) −x+5/2, y−1/2, −z+1/2.

Experimental details

Crystal data
Chemical formula	2CH₆N₃⁺·2Br⁻·C₁₂H₂₄O₆
M_r	544.31
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	293
a, b, c (Å)	8.9354 (18), 9.860 (2), 14.306 (3)
β (°)	101.39 (3)
V (Å³)	1235.6 (4)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	3.32
Crystal size (mm)	0.20 × 0.20 × 0.20

Data collection
Diffractometer	Rigaku SCXmini diffractometer
Absorption correction	Multi-scan (CrystalClear; Rigaku, 2005)
T_min, T_max	0.936, 0.937
No. of measured, independent and observed [I > 2σ(I)] reflections	12464, 2835, 1968
R_int	0.077
(sin θ/λ)_max (Å⁻¹)	0.649

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.053, 0.127, 1.11
No. of reflections	2835
No. of parameters	127
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.36, −0.79

Computer programs: CrystalClear (Rigaku, 2005), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···Br1ⁱ	0.86	2.68	3.470 (3)	154.2
N1—H1B···O2	0.86	2.14	2.938 (4)	154.6
N2—H2C···O2	0.86	2.40	3.127 (5)	143.3
N2—H2D···Br1	0.86	2.82	3.582 (4)	149.1
N3—H3D···Br1	0.86	2.53	3.354 (3)	162.0
N3—H3C···Br1ⁱ	0.86	2.64	3.440 (3)	155.6

Symmetry code: (i) −x+5/2, y−1/2, −z+1/2.

Acknowledgements

The author is grateful to the starter fund of Southeast University for the purchase of the diffractometer.

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