A polymorph of tetra­ethyl­ammonium chloride

Abstract

The structure of the title compound, C₈H₂₀N⁺·Cl⁻, is compared with a polymorph that was described earlier in the same space group. Differences in the conformations of the ethyl groups of the cation exist between the polymorphs. This study is given here in order to provide additional unit-cell data for use in qualitative identification of crystalline samples obtained in syntheses in which Et₄N⁺·Cl⁻ is either used or generated.

Related literature

A polymorph with three mol­ecules in the asymmetric unit was earlier solved in the P2₁/n setting of this same space group (Staples, 1999 ▶). A discussion of crystal growth conditions that can affect the occurrence of polymorphs has been given by Hulliger (1994 ▶). For descriptions of chemistry involving tetra­ethyl­ammonium chloride, see: McCleverty et al. (1967 ▶); Lorber et al. (1998 ▶); Donahue et al. (1998 ▶).

Experimental

Crystal data

• C₈H₂₀N⁺·Cl⁻

• M _r = 165.70

• Monoclinic,

• a = 8.429 (2) Å

• b = 8.109 (2) Å

• c = 14.499 (4) Å

• β = 91.378 (3)°

• V = 990.7 (4) ų

• Z = 4

• Mo Kα radiation

• μ = 0.32 mm⁻¹

• T = 100 K

• 0.20 × 0.14 × 0.12 mm

Data collection

• Bruker APEXII CCD diffractometer

• Absorption correction: multi-scan (SADABS; Sheldrick, 2008b ▶) T _min = 0.876, T _max = 0.963

• 8314 measured reflections

• 2302 independent reflections

• 2038 reflections with I > 2σ(I)

• R _int = 0.032

Refinement

• R[F ² > 2σ(F ²)] = 0.030

• wR(F ²) = 0.083

• S = 1.03

• 2302 reflections

• 95 parameters

• H-atom parameters constrained

• Δρ_max = 0.33 e Å⁻³

• Δρ_min = −0.21 e Å⁻³

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker 2008 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008a ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008a ▶); molecular graphics: SHELXTL (Sheldrick, 2008a ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

supplementary crystallographic information

Comment

Tetraethylammonium chloride, Et₄N⁺Cl^- (Scheme 1), is frequently employed in inorganic synthesis as a convenient source of soluble countercations for anionic metal species. For instance, Et₄N⁺Cl^- is added to the reaction mixture in which Na₂[Fe₂(mnt)₄] is formed from Na₂(mnt) and FeCl₃ (mnt = (CN)₂C₂S₂(2-) = maleonitriledithiolate(2-)), thereby providing a metallodithiolene product that has useful solubility in common organic solvents (McCleverty et al., 1967). In other instances, Et₄N⁺Cl^- is generated as a byproduct of synthesis, as in the preparation of [Et₄N][M(OSiMe₃)(bdt)₂] (M = Mo or W; bdt = benzene-1,2-dithiolate(2-)) by silylation of the corresponding oxo bis(dithiolene) dianion (Lorber et al., 1998; Donahue et al., 1998). The frequency with which Et₄N⁺Cl^- is used or otherwise encountered in inorganic synthesis, and the ease with which crystalline samples may be occluded with colored impurities that obscure their identity, make desirable the availability of complete crystallographic data for this compound as a means for qualitatively identifying it and avoiding needless data collections.

White parallelpiped crystals of Et₄N⁺Cl^- grew without disorder (Fig. 1) in monoclinic space group P2₁/c with only one formula unit in the asymmetric unit and a Z value of 4 (Fig. 2). A view of the tetraethylammonium cation that is approximately orthogonal to a mean plane projection of the C and N atoms shows a propeller-like disposition of the ethyl groups around the central N atom (Fig. 1).

Experimental

White parallelpiped crystals of Et₄N⁺Cl^- grew by diffusion of Et₂O vapor into an acetonitrile solution under a dry, N₂ atmosphere.

Refinement

H atoms were placed in calculated positions (C—H = 0.98–0.99 Å) and included as riding contributions with isotropic displacement parameters 1.2–1.5 times those of the attached C atoms.

Figures

Fig. 1.

Et4N+Cl- shown with 50% probability ellipsoids.

Fig. 2.

Unit cell of Et4N+Cl- in P21/c.

Crystal data

C8H20N+·Cl−	F(000) = 368
Mr = 165.70	Dx = 1.111 Mg m−3
Monoclinic, P21/c	Melting point: not measured K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 8.429 (2) Å	Cell parameters from 5930 reflections
b = 8.109 (2) Å	θ = 2.4–28.5°
c = 14.499 (4) Å	µ = 0.32 mm−1
β = 91.378 (3)°	T = 100 K
V = 990.7 (4) Å3	Parallelepiped, colourless
Z = 4	0.20 × 0.14 × 0.12 mm

Data collection

Bruker APEXII CCD diffractometer	2302 independent reflections
Radiation source: fine-focus sealed tube	2038 reflections with I > 2σ(I)
graphite	Rint = 0.032
φ and ω scans	θmax = 27.8°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Sheldrick, 2008a)	h = −10→10
Tmin = 0.876, Tmax = 0.963	k = −10→10
8314 measured reflections	l = −18→18

Refinement

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)] = 0.030	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.083	H-atom parameters constrained
S = 1.03	w = 1/[σ2(Fo2) + (0.0437P)2 + 0.2706P] where P = (Fo2 + 2Fc2)/3
2302 reflections	(Δ/σ)max = 0.001
95 parameters	Δρmax = 0.33 e Å−3
0 restraints	Δρmin = −0.21 e Å−3

Special details

Experimental. The diffraction data were collected in three sets of 606 frames (0.3 °. width in ω) at φ = 0, 120 and 240 °. A scan time of 30 sec/frame was used.

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
Cl1	0.24449 (3)	0.49267 (3)	0.660880 (18)	0.02030 (10)
N1	0.25555 (10)	0.10663 (10)	0.86208 (6)	0.01401 (19)
C1	0.30638 (13)	0.09217 (13)	0.76286 (7)	0.0177 (2)
H1A	0.4027	0.0225	0.7610	0.021*
H1B	0.3350	0.2032	0.7402	0.021*
C2	0.18066 (15)	0.01931 (15)	0.69818 (8)	0.0252 (3)
H2A	0.1584	−0.0945	0.7166	0.038*
H2B	0.2191	0.0203	0.6349	0.038*
H2C	0.0833	0.0850	0.7012	0.038*
C3	0.19934 (13)	−0.05808 (13)	0.90007 (8)	0.0182 (2)
H3A	0.1879	−0.0473	0.9676	0.022*
H3B	0.0930	−0.0825	0.8730	0.022*
C4	0.30819 (14)	−0.20341 (14)	0.88139 (8)	0.0232 (2)
H4A	0.3011	−0.2321	0.8157	0.035*
H4B	0.2758	−0.2983	0.9183	0.035*
H4C	0.4178	−0.1735	0.8981	0.035*
C5	0.11843 (12)	0.22872 (13)	0.86575 (7)	0.0176 (2)
H5A	0.1432	0.3248	0.8265	0.021*
H5B	0.0218	0.1756	0.8393	0.021*
C6	0.08328 (14)	0.28976 (15)	0.96222 (8)	0.0251 (3)
H6A	0.0840	0.1963	1.0051	0.038*
H6B	−0.0213	0.3426	0.9619	0.038*
H6C	0.1644	0.3697	0.9819	0.038*
C7	0.39616 (12)	0.16349 (13)	0.92106 (7)	0.0167 (2)
H7A	0.4806	0.0789	0.9185	0.020*
H7B	0.3629	0.1720	0.9859	0.020*
C8	0.46431 (14)	0.32803 (14)	0.89185 (8)	0.0243 (3)
H8A	0.5208	0.3142	0.8340	0.036*
H8B	0.5382	0.3684	0.9400	0.036*
H8C	0.3780	0.4078	0.8827	0.036*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Cl1	0.01788 (16)	0.02294 (16)	0.02008 (16)	−0.00039 (9)	0.00052 (11)	0.00271 (9)
N1	0.0142 (4)	0.0146 (4)	0.0132 (4)	0.0006 (3)	0.0001 (3)	0.0003 (3)
C1	0.0206 (5)	0.0200 (5)	0.0125 (5)	0.0022 (4)	0.0023 (4)	−0.0006 (4)
C2	0.0280 (6)	0.0301 (6)	0.0174 (6)	0.0023 (5)	−0.0054 (5)	−0.0035 (4)
C3	0.0202 (5)	0.0158 (5)	0.0185 (5)	−0.0023 (4)	0.0002 (4)	0.0027 (4)
C4	0.0281 (6)	0.0158 (5)	0.0256 (6)	0.0021 (4)	−0.0023 (5)	0.0008 (4)
C5	0.0158 (5)	0.0183 (5)	0.0187 (5)	0.0045 (4)	0.0008 (4)	0.0006 (4)
C6	0.0265 (6)	0.0276 (6)	0.0214 (6)	0.0090 (5)	0.0053 (4)	−0.0007 (4)
C7	0.0164 (5)	0.0182 (5)	0.0153 (5)	−0.0009 (4)	−0.0029 (4)	−0.0002 (4)
C8	0.0249 (6)	0.0224 (6)	0.0253 (6)	−0.0062 (5)	−0.0035 (5)	0.0013 (4)

Geometric parameters (Å, °)

N1—C1	1.5153 (13)	C4—H4B	0.9800
N1—C7	1.5165 (13)	C4—H4C	0.9800
N1—C5	1.5238 (13)	C5—C6	1.5197 (16)
N1—C3	1.5246 (13)	C5—H5A	0.9900
C1—C2	1.5178 (16)	C5—H5B	0.9900
C1—H1A	0.9900	C6—H6A	0.9800
C1—H1B	0.9900	C6—H6B	0.9800
C2—H2A	0.9800	C6—H6C	0.9800
C2—H2B	0.9800	C7—C8	1.5170 (15)
C2—H2C	0.9800	C7—H7A	0.9900
C3—C4	1.5219 (15)	C7—H7B	0.9900
C3—H3A	0.9900	C8—H8A	0.9800
C3—H3B	0.9900	C8—H8B	0.9800
C4—H4A	0.9800	C8—H8C	0.9800
C1—N1—C7	108.90 (8)	C3—C4—H4C	109.5
C1—N1—C5	108.39 (8)	H4A—C4—H4C	109.5
C7—N1—C5	111.46 (8)	H4B—C4—H4C	109.5
C1—N1—C3	111.88 (8)	C6—C5—N1	114.12 (9)
C7—N1—C3	107.94 (8)	C6—C5—H5A	108.7
C5—N1—C3	108.30 (8)	N1—C5—H5A	108.7
N1—C1—C2	114.05 (9)	C6—C5—H5B	108.7
N1—C1—H1A	108.7	N1—C5—H5B	108.7
C2—C1—H1A	108.7	H5A—C5—H5B	107.6
N1—C1—H1B	108.7	C5—C6—H6A	109.5
C2—C1—H1B	108.7	C5—C6—H6B	109.5
H1A—C1—H1B	107.6	H6A—C6—H6B	109.5
C1—C2—H2A	109.5	C5—C6—H6C	109.5
C1—C2—H2B	109.5	H6A—C6—H6C	109.5
H2A—C2—H2B	109.5	H6B—C6—H6C	109.5
C1—C2—H2C	109.5	N1—C7—C8	113.96 (8)
H2A—C2—H2C	109.5	N1—C7—H7A	108.8
H2B—C2—H2C	109.5	C8—C7—H7A	108.8
C4—C3—N1	114.85 (9)	N1—C7—H7B	108.8
C4—C3—H3A	108.6	C8—C7—H7B	108.8
N1—C3—H3A	108.6	H7A—C7—H7B	107.7
C4—C3—H3B	108.6	C7—C8—H8A	109.5
N1—C3—H3B	108.6	C7—C8—H8B	109.5
H3A—C3—H3B	107.5	H8A—C8—H8B	109.5
C3—C4—H4A	109.5	C7—C8—H8C	109.5
C3—C4—H4B	109.5	H8A—C8—H8C	109.5
H4A—C4—H4B	109.5	H8B—C8—H8C	109.5
C7—N1—C1—C2	174.07 (9)	C1—N1—C5—C6	−164.83 (9)
C5—N1—C1—C2	−64.51 (11)	C7—N1—C5—C6	−45.00 (12)
C3—N1—C1—C2	54.83 (11)	C3—N1—C5—C6	73.60 (11)
C1—N1—C3—C4	47.32 (11)	C1—N1—C7—C8	58.94 (11)
C7—N1—C3—C4	−72.47 (11)	C5—N1—C7—C8	−60.59 (11)
C5—N1—C3—C4	166.71 (9)	C3—N1—C7—C8	−179.40 (9)