Dimethyl­ammonium tetra­chloridoferrate(III) 18-crown-6 clathrate

Shi, P.P.; Zhao, M.M.

doi:10.1107/S1600536810020192

metal-organic compounds

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Volume 66| Part 7| July 2010| Page m728

doi:10.1107/S1600536810020192

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Dimethylammonium tetrachloridoferrate(III) 18-crown-6 clathrate

Ping Ping Shi ^a and Min Min Zhao ^a ^*

^aOrdered Matter Science Research Center, College of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, People's Republic of China
^*Correspondence e-mail: zmmzyahfdzg@126.com

(Received 20 May 2010; accepted 28 May 2010; online 5 June 2010)

The reaction of dimethylamine hydrochloride, 18-crown-6 and ferric chloride in ethanol yields the title compound, (C₂H₈N)[FeCl₄]·C₁₂H₂₄O₆, which exhibits an unusual supramolecular structure. The protonated dimethylamine contains one NH₂⁺ group, resulting in a 1:1 supramolecular rotator–stator structure (CH₃—NH₂⁺—CH₃)(18-crown-6), through N—H⋯O hydrogen-bonding interactions between the ammonium group of the cation and the O atoms of the crown ether. In the crystal, all three components lie on a common crystallographic mirror plane normal to [010].

Related literature

For similar 18-crown-6 clathrates, see: Akutagawa et al. (2002 ); Fender et al. (2002 ). For the ferroelectric properties of these materials, see: Zhang et al. (2009 ); Ye et al. (2009 ).

Experimental

Crystal data

(C₂H₈N)[FeCl₄]·C₁₂H₂₄O₆
M_r = 508.06
Orthorhombic, P n m a
a = 9.3035 (19) Å
b = 11.328 (2) Å
c = 23.230 (5) Å
V = 2448.1 (9) Å³
Z = 4
Mo Kα radiation
μ = 1.08 mm⁻¹
T = 293 K
0.40 × 0.30 × 0.20 mm

Data collection

Rigaku SCXmini diffractometer
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005 ) T_min = 0.685, T_max = 0.806
23771 measured reflections
2940 independent reflections
1799 reflections with I > 2σ(I)
R_int = 0.073

Refinement

R[F² > 2σ(F²)] = 0.052
wR(F²) = 0.128
S = 0.99
2940 reflections
130 parameters
H-atom parameters constrained
Δρ_max = 0.33 e Å⁻³
Δρ_min = −0.23 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1C⋯O2ⁱ	0.90	2.03	2.867 (3)	155
Symmetry code: (i) $[x, -y+{\script{1\over 2}}, z]$ .

Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: PRPKAPPA (Ferguson, 1999 ).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810020192/bh2286sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536810020192/bh2286Isup2.hkl

checkCIF report

Comment top

There is currently a great deal of interest in crown ethers because of their ability to form non-covalent, H-bonding complexes with ammonium cations, both in solid and in solution (Akutagawa et al., 2002; Fender et al., 2002). Not only the size of the crown ether, but also the nature of the ammonium cation (NH₄⁺, RNH₃⁺, R₂NH₂⁺, etc.) can influence on the stoichiometry and stability of these host–guest complexes. The host molecules combine with the guest species by intermolecular interactions, and, if the host molecule contains some specific sites, it is easy to realise high selectivity in ion or molecular recognition. 18-Crown-6 has the highest affinity for ammonium cations RNH₃⁺. While most studies of 18-crown-6 and its derivatives invariably showed a 1:1 stoichiometry with RNH₃⁺ cations, some structurally characterized complexes of crown ethers include R₂NH₂⁺ cations.

The present study is a part of systematic investigation of ferroelectric, phase transitions materials (Ye et al., 2009; Zhang et al., 2009) that include metal-organic coordination compounds with organic ligands, or are related to the structures with both organic and inorganic building fragments. In the measured temperature range from 80 to 420 K (m.p. > 430 K), the temperature dependence of the relative permittivity at 1 MHz varied smoothly from 4.6 to 7.2 in the title compound. No dielectric anomaly has been observed. This suggests that this compound is not an actual ferroelectric, or that no distinct phase transition occurred within the probed temperature range.

The title compound is composed of cationic [C₂H₈N (18-Crown-6)]⁺ and one single anionic [FeCl₄]^- complex (Fig. 1). Supramolecular rotators are assembled between protonated dimethylamine (CH₃—NH₂—CH₃)⁺ and 18-crown-6 by hydrogen-bonding. The ammonium moieties of (NH₂⁺) cations interact with two O atoms of the crown ether through two simple N—H···O hydrogen bonds, forming a 1:1 supramolecular rotator-stator structure.

Supramolecular cation structure, [C₂H₈N (18-Crown-6)]⁺, were introduced as counter cations to [FeCl₄]^- anions. The crown adopts a conformation in which the ring shows some distortion from the mean plane, with the torsion angles: C3—O2—C2—C1 = 178.2 (3)°; C2—O2—C3—C4 = 72.6 (4)°; C5—O3—C4—C3=178.9 (3)°; C4—O3—C5—C6 = 179.5 (3)°; O3—C4—C3—O2=61.0 (5)°. Fe(III) has a flattened tetrahedral coordination by four Cl^- ions [range of cis-bond angles: 108.14 (4)–111.67 (9)°; dav (Fe—Cl) = 2.1728 (15)–2.1889 (12) Å].

Fig. 2 shows a view of the crystal structure down the a axis. An alternate arrangement of cations and anions layers is elongated along the b axis. The title compound is stabilized by intramolecular N—H···O hydrogen bonds, but no significant intermolecular hydrogen bonds are observed.

Related literature top

For similar 18-crown-6 clathrates, see: Akutagawa et al. (2002); Fender et al. (2002). For the ferroelectric properties of these materials, see: Zhang et al. (2009); Ye et al. (2009).

Experimental top

CH₃—NH—CH₃.HCl (2 mmol, 0.163 g) and 18-crown-6 (2 mmol, 0.528 g) were dissolved in ethanol. Then, trivalent ferric chloride (2 mmol, 0.54 g) was added to the mixture in concentrated hydrochloric acid medium, the precipitate was filtered and washed with a small amount of ethanol. Five days later, single crystals suitable for X-ray diffraction analysis were obtained from slow evaporation of ethanol and DMF solution at room temperature.

Computing details top

Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear (Rigaku, 2005); data reduction: CrystalClear (Rigaku, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: PRPKAPPA (Ferguson, 1999).

Figures top

	Fig. 1. The title compound, with the atomic numbering scheme. The displacement ellipsoids are drawn at the 30% probability level.
	Fig. 2. A view of the structure along the a axis. The dashed lines depict the hydrogen bonds.

Dimethylammonium tetrachloridoferrate(III)–1,4,7,10,13,16-hexaoxacyclooctadecane (1/1) top

Crystal data top

(C₂H₈N)[FeCl₄]·C₁₂H₂₄O₆	F(000) = 1060
M_r = 508.06	D_x = 1.378 Mg m⁻³
Orthorhombic, Pnma	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2n	Cell parameters from 17071 reflections
a = 9.3035 (19) Å	θ = 3.2–27.8°
b = 11.328 (2) Å	µ = 1.08 mm⁻¹
c = 23.230 (5) Å	T = 293 K
V = 2448.1 (9) Å³	Prism, yellow
Z = 4	0.40 × 0.30 × 0.20 mm

Data collection top

Rigaku SCXmini diffractometer	2940 independent reflections
Radiation source: fine-focus sealed tube	1799 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.073
Detector resolution: 13.6612 pixels mm^-1	θ_max = 27.5°, θ_min = 3.2°
CCD_Profile_fitting scans	h = −12→12
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)	k = −14→14
T_min = 0.685, T_max = 0.806	l = −30→30
23771 measured 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)] = 0.052	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.128	H-atom parameters constrained
S = 0.99	w = 1/[σ²(F_o²) + (0.04P)² + 1.99P] where P = (F_o² + 2F_c²)/3
2940 reflections	(Δ/σ)_max < 0.001
130 parameters	Δρ_max = 0.33 e Å⁻³
0 restraints	Δρ_min = −0.23 e Å⁻³
0 constraints

Crystal data top

(C₂H₈N)[FeCl₄]·C₁₂H₂₄O₆	V = 2448.1 (9) Å³
M_r = 508.06	Z = 4
Orthorhombic, Pnma	Mo Kα radiation
a = 9.3035 (19) Å	µ = 1.08 mm⁻¹
b = 11.328 (2) Å	T = 293 K
c = 23.230 (5) Å	0.40 × 0.30 × 0.20 mm

Data collection top

Rigaku SCXmini diffractometer	2940 independent reflections
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)	1799 reflections with I > 2σ(I)
T_min = 0.685, T_max = 0.806	R_int = 0.073
23771 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.052	0 restraints
wR(F²) = 0.128	H-atom parameters constrained
S = 0.99	Δρ_max = 0.33 e Å⁻³
2940 reflections	Δρ_min = −0.23 e Å⁻³
130 parameters

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

	x	y	z	U_iso*/U_eq
Fe1	0.47623 (7)	0.2500	0.38202 (3)	0.0633 (2)
Cl2	0.25400 (14)	0.2500	0.35240 (7)	0.0926 (5)
Cl1	0.61871 (16)	0.2500	0.30791 (6)	0.0890 (4)
Cl3	0.51101 (12)	0.09011 (13)	0.43307 (5)	0.1218 (5)
O1	−0.1251 (4)	0.2500	0.57334 (13)	0.0776 (10)
O2	0.0327 (3)	0.0373 (2)	0.58570 (10)	0.0804 (7)
O4	0.0916 (4)	0.2500	0.76754 (13)	0.0731 (9)
O3	0.1171 (3)	0.0390 (2)	0.70458 (11)	0.0814 (7)
C2	−0.1174 (4)	0.0408 (4)	0.5777 (2)	0.0991 (14)
H2A	−0.1646	0.0442	0.6144	0.119*
H2B	−0.1483	−0.0298	0.5584	0.119*
C4	0.0511 (5)	−0.0599 (3)	0.67999 (18)	0.0899 (12)
H4A	−0.0510	−0.0556	0.6856	0.108*
H4B	0.0856	−0.1305	0.6982	0.108*
C6	0.1585 (5)	0.1474 (4)	0.78905 (16)	0.0929 (12)
H6A	0.1503	0.1454	0.8302	0.111*
H6B	0.2587	0.1480	0.7793	0.111*
C3	0.0837 (5)	−0.0633 (3)	0.61760 (18)	0.0901 (12)
H3A	0.1859	−0.0689	0.6128	0.108*
H3B	0.0418	−0.1334	0.6014	0.108*
C1	−0.1581 (5)	0.1448 (4)	0.54302 (18)	0.1033 (15)
H1A	−0.1071	0.1438	0.5071	0.124*
H1B	−0.2592	0.1424	0.5348	0.124*
C5	0.0908 (5)	0.0448 (4)	0.76473 (16)	0.0910 (12)
H5A	0.1280	−0.0249	0.7830	0.109*
H5B	−0.0108	0.0478	0.7717	0.109*
N1	0.1943 (4)	0.2500	0.60266 (16)	0.0631 (10)
H1C	0.1395	0.3142	0.6088	0.076*
C8	0.3114 (6)	0.2500	0.6442 (2)	0.0885 (16)
H8A	0.2746	0.2500	0.6828	0.133*
H8B	0.3692	0.1808	0.6383	0.133*
C7	0.2423 (7)	0.2500	0.5428 (2)	0.107 (2)
H7A	0.1606	0.2500	0.5175	0.161*
H7B	0.2992	0.3192	0.5358	0.161*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Fe1	0.0520 (4)	0.0775 (5)	0.0602 (4)	0.000	−0.0032 (3)	0.000
Cl2	0.0602 (7)	0.0757 (9)	0.1419 (13)	0.000	−0.0276 (8)	0.000
Cl1	0.0893 (10)	0.1058 (11)	0.0719 (8)	0.000	0.0172 (7)	0.000
Cl3	0.0934 (8)	0.1508 (12)	0.1212 (9)	0.0227 (7)	0.0078 (6)	0.0725 (9)
O1	0.076 (2)	0.098 (3)	0.0589 (19)	0.000	−0.0134 (17)	0.000
O2	0.0754 (16)	0.0766 (17)	0.0892 (17)	−0.0121 (13)	0.0188 (13)	−0.0222 (14)
O4	0.080 (2)	0.076 (2)	0.064 (2)	0.000	−0.0125 (17)	0.000
O3	0.0913 (18)	0.0591 (15)	0.0937 (18)	0.0036 (13)	0.0070 (14)	−0.0007 (13)
C2	0.080 (3)	0.098 (3)	0.120 (4)	−0.019 (2)	0.008 (2)	−0.045 (3)
C4	0.097 (3)	0.058 (2)	0.115 (3)	0.007 (2)	0.017 (2)	−0.001 (2)
C6	0.092 (3)	0.113 (3)	0.074 (2)	0.018 (3)	−0.015 (2)	0.019 (2)
C3	0.103 (3)	0.050 (2)	0.117 (3)	0.003 (2)	0.031 (3)	−0.013 (2)
C1	0.082 (3)	0.145 (4)	0.083 (3)	−0.005 (3)	−0.020 (2)	−0.034 (3)
C5	0.106 (3)	0.082 (3)	0.085 (3)	0.012 (2)	−0.007 (2)	0.022 (2)
N1	0.050 (2)	0.060 (2)	0.080 (3)	0.000	0.0050 (19)	0.000
C8	0.066 (3)	0.114 (5)	0.086 (4)	0.000	−0.009 (3)	0.000
C7	0.113 (5)	0.141 (6)	0.069 (4)	0.000	0.010 (3)	0.000

Geometric parameters (Å, º) top

Fe1—Cl1	2.1728 (15)	C4—H4B	0.9599
Fe1—Cl2	2.1791 (14)	C6—C5	1.437 (5)
Fe1—Cl3ⁱ	2.1889 (12)	C6—H6A	0.9601
Fe1—Cl3	2.1889 (12)	C6—H6B	0.9600
O1—C1	1.418 (4)	C3—H3A	0.9600
O1—C1ⁱ	1.418 (4)	C3—H3B	0.9601
O2—C2	1.410 (4)	C1—H1A	0.9599
O2—C3	1.440 (4)	C1—H1B	0.9600
O4—C6ⁱ	1.410 (4)	C5—H5A	0.9600
O4—C6	1.410 (4)	C5—H5B	0.9600
O3—C4	1.399 (4)	N1—C8	1.455 (6)
O3—C5	1.420 (4)	N1—C7	1.461 (6)
C2—C1	1.476 (6)	N1—H1C	0.9000
C2—H2A	0.9601	C8—H8A	0.9599
C2—H2B	0.9600	C8—H8B	0.9601
C4—C3	1.481 (5)	C7—H7A	0.9600
C4—H4A	0.9600	C7—H7B	0.9600

Cl1—Fe1—Cl2	109.19 (7)	O2—C3—C4	114.5 (3)
Cl1—Fe1—Cl3ⁱ	109.82 (4)	O2—C3—H3A	108.6
Cl2—Fe1—Cl3ⁱ	108.14 (4)	C4—C3—H3A	108.6
Cl1—Fe1—Cl3	109.82 (4)	O2—C3—H3B	108.6
Cl2—Fe1—Cl3	108.14 (4)	C4—C3—H3B	108.7
Cl3ⁱ—Fe1—Cl3	111.67 (9)	H3A—C3—H3B	107.6
C1—O1—C1ⁱ	114.3 (4)	O1—C1—C2	110.1 (3)
C2—O2—C3	114.6 (3)	O1—C1—H1A	109.6
C6ⁱ—O4—C6	111.1 (4)	C2—C1—H1A	109.7
C4—O3—C5	111.3 (3)	O1—C1—H1B	109.6
O2—C2—C1	110.4 (4)	C2—C1—H1B	109.6
O2—C2—H2A	109.7	H1A—C1—H1B	108.2
C1—C2—H2A	109.5	O3—C5—C6	110.4 (3)
O2—C2—H2B	109.6	O3—C5—H5A	109.6
C1—C2—H2B	109.5	C6—C5—H5A	109.4
H2A—C2—H2B	108.1	O3—C5—H5B	109.6
O3—C4—C3	109.3 (3)	C6—C5—H5B	109.6
O3—C4—H4A	109.8	H5A—C5—H5B	108.1
C3—C4—H4A	109.7	C8—N1—C7	113.7 (4)
O3—C4—H4B	109.9	C8—N1—H1C	108.6
C3—C4—H4B	109.9	C7—N1—H1C	109.0
H4A—C4—H4B	108.3	N1—C8—H8A	110.6
O4—C6—C5	109.5 (3)	N1—C8—H8B	108.9
O4—C6—H6A	109.7	H8A—C8—H8B	109.5
C5—C6—H6A	109.8	N1—C7—H7A	109.9
O4—C6—H6B	109.8	N1—C7—H7B	109.3
C5—C6—H6B	109.8	H7A—C7—H7B	109.5
H6A—C6—H6B	108.2

Symmetry code: (i) x, −y+1/2, z.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1C···O2ⁱ	0.90	2.03	2.867 (3)	155

Symmetry code: (i) x, −y+1/2, z.

Experimental details

Crystal data
Chemical formula	(C₂H₈N)[FeCl₄]·C₁₂H₂₄O₆
M_r	508.06
Crystal system, space group	Orthorhombic, Pnma
Temperature (K)	293
a, b, c (Å)	9.3035 (19), 11.328 (2), 23.230 (5)
V (Å³)	2448.1 (9)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	1.08
Crystal size (mm)	0.40 × 0.30 × 0.20

Data collection
Diffractometer	Rigaku SCXmini diffractometer
Absorption correction	Multi-scan (CrystalClear; Rigaku, 2005)
T_min, T_max	0.685, 0.806
No. of measured, independent and observed [I > 2σ(I)] reflections	23771, 2940, 1799
R_int	0.073
(sin θ/λ)_max (Å⁻¹)	0.649

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.052, 0.128, 0.99
No. of reflections	2940
No. of parameters	130
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.33, −0.23

Computer programs: CrystalClear (Rigaku, 2005), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008), PRPKAPPA (Ferguson, 1999).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1C···O2ⁱ	0.90	2.03	2.867 (3)	155.1

Symmetry code: (i) x, −y+1/2, z.

Acknowledgements

The authors are grateful to the starter fund of Southeast University for financial support to buy the X-ray diffractometer.

References

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doi:10.1107/S1600536810020192

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