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Acta Cryst. (2008). E64, o601    [ doi:10.1107/S1600536808002481 ]

Benzylethyldimethylammonium bromide

M. Hodorowicz and K. Stadnicka

Abstract top

The crystal structure of the title compound, C11H18N+·Br-, has been determined as part of an ongoing study of the influence of the alkyl chain length on amphiphilic activity of quaternary ammonium salts. The title salt forms a three-dimensional network of ionic contacts through weak C-H...Br hydrogen bonds, with donor-acceptor distances in the range 3.757 (2)-3.959 (2) Å, in which methyl groups serve as donors.

Comment top

Quaternary alkylammonium salts are widely used to modify natural clay minerals into hydrophobic organo-clays which exhibit high capability to remove hydrophobic contaminants from aqueous solutions (Ogawa & Kuroda, 1997). From the systematic study of the relation between the crystal structures of chosen homologous benzyldimethylalkylammonium bromides and their cations' ability for sorption on clay minerals (Kwolek et al., 2003; Hodorowicz et al., 2003, 2005), it became obvious that the hydrophobic interactions are responsible for an alkyl-chain bilayer formation when the long-chain (n = 8–12) ammonium cations are adsorbed on montmorillonite (Hodorowicz et al., 2005), whereas a different way of cation packing seems to dominate in the case of short-chain ammonium cations (Kwolek et al., 2003). The crystal structure analysis of benzyldimethylethylammonium bromide was performed to find out the influence of molecular geometry, and the length of the alkyl chain in particular, on the packing properties of the ammonium cations. The structure of the title compound is shown in Fig. 1. The asymmetric unit is composed of a quaternary ammonium cation and a bromide counterion (N+···Br- = 4.439 (2) Å). The bond lengths and angles indicate the typical tetrahedral arragement of the substituents at the N atom. The molecular dimensions are comparable with the values reported in the literature (Allen et al., 1987). Methyl and methylene groups of the quaternary ammonium cation as well as C—H of the benzene ring are involved in weak intermolecular interactions of the C—H···Br- type (Table 1). There are also relatively strong interactions of the C—H···π type observed between the C2 methyl group and the π system of the benzene ring, which result in cation chains along [100] (Fig. 2). The chains are joined into layers parallel to (010) due to C—H···Br- interactions (Fig. 3). The interactions are also responsible for packing of the layers along [010], as shown in Fig. 4. Each layer consists of cations inclined to the anionic layer and arranged in a zig—zag 'head-to-tail' system. The thickness of the layer is b/2. The observed architecture of the short-chain ammonium cation layers, best seen in Figs. 3 and 4, could be considered as a model for the organic cation layers intercalated into the montmorillonite structure (Kwolek et al., 2003).

Related literature top

For related literature, see: Ogawa & Kuroda (1997); Hodorowicz et al. (2003, 2005); Kwolek et al. (2003); Allen et al. (1987).

Experimental top

The title compound was prepared by dissolving a 1:1 mixture of bromoethane and N,N-dimethylbenzylamine in acetone at 273 K. The solution was slowly heated to room temperature to give colourless single crystals of the title compound. Recrystallization from acetone afforded crystals suitable for X-ray measurements.

Refinement top

All hydrogen atom positions were observed in a difference Fourier map. Nevertheless, in the refinement procedure the hydrogen atoms were positioned geometrically and refined using a riding model, with C—H = C—H = 0.97 Å for CH2 groups, 0.96 Å for CH3 groups, and 0.93 Å for aromatic CH, and with Uiso(H) = 1.5Ueq(C) for methyl groups and Uiso(H) = 1.2Ueq(C) for all other H atoms.

Computing details top

Data collection: COLLECT (Nonius, 2000); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO (Otwinowski & Minor, 1997) and SCALEPACK; program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and DIAMOND (Brandenburg, 2006); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. ORTEP-3 (Farrugia, 1997) drawing of the asymmetric unit with atom labels. Displacement ellipsoids of non-H atoms are drawn at the 30% probabilty level.
[Figure 2] Fig. 2. Chain of benzyldimethylethylammonium cations along [100] projected onto (010). The chain is formed due to C—H···π interactions (ORTEP-3; Farrugia, 1997).
[Figure 3] Fig. 3. Layers parallel to (010) and built of the ammonium cations, arranged in a zig—zag 'head-to-tail' system, are joined together through Br counterions. View along [100] (ORTEP-3; Farrugia, 1997).
[Figure 4] Fig. 4. The sequence of the cationic and anionic layers along [010] in projecton onto (100) (DIAMOND; Brandenburg, 2006).
Benzylethyldimethylammonium bromide top
Crystal data top
C11H18N+·Br–F000 = 504
Mr = 244.17Dx = 1.364 Mg m−3
Orthorhombic, P212121Mo Kα radiation
λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 2258 reflections
a = 6.7765 (1) Åθ = 1.0–31.5º
b = 12.5827 (2) ŵ = 3.42 mm−1
c = 13.9433 (2) ÅT = 293 (2) K
V = 1188.90 (3) Å3Prism, colourless
Z = 40.20 × 0.19 × 0.17 mm
Data collection top
Nonius KappaCCD
diffractometer		3874 independent reflections
Radiation source: fine-focus sealed tube3483 reflections with I > 2σ(I)
Monochromator: horizontally mounted graphite crystalRint = 0.041
Detector resolution: 9 pixels mm-1θmax = 31.5º
T = 293(2) Kθmin = 2.9º
φ and ω scansh = 0→9
Absorption correction: multi-scan
(DENZO and SCALEPACK Otwinowski & Minor, 1997)		k = 0→18
Tmin = 0.548, Tmax = 0.594l = −20→20
18366 measured reflections
Refinement top
Refinement on F2H-atom parameters constrained
Least-squares matrix: full  w = 1/[σ2(Fo2) + (0.0247P)2 + 0.2756P]
where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.027(Δ/σ)max = 0.001
wR(F2) = 0.065Δρmax = 0.26 e Å−3
S = 1.07Δρmin = −0.49 e Å−3
3874 reflectionsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
119 parametersExtinction coefficient: 0.045 (2)
Primary atom site location: structure-invariant direct methodsAbsolute structure: Flack (1983), 1627 Friedel pairs
Secondary atom site location: difference Fourier mapFlack parameter: 0.002 (9)
Hydrogen site location: inferred from neighbouring sites
Crystal data top
C11H18N+·Br–V = 1188.90 (3) Å3
Mr = 244.17Z = 4
Orthorhombic, P212121Mo Kα
a = 6.7765 (1) ŵ = 3.42 mm−1
b = 12.5827 (2) ÅT = 293 (2) K
c = 13.9433 (2) Å0.20 × 0.19 × 0.17 mm
Data collection top
Nonius KappaCCD
diffractometer		3874 independent reflections
Absorption correction: multi-scan
(DENZO and SCALEPACK Otwinowski & Minor, 1997)		3483 reflections with I > 2σ(I)
Tmin = 0.548, Tmax = 0.594Rint = 0.041
18366 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.027H-atom parameters constrained
wR(F2) = 0.065Δρmax = 0.26 e Å−3
S = 1.07Δρmin = −0.49 e Å−3
3874 reflectionsAbsolute structure: Flack (1983), 1627 Friedel pairs
119 parametersFlack parameter: 0.002 (9)
Special details top

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 (Å2) top
xyzUiso*/Ueq
Br10.29436 (3)1.294368 (16)0.812541 (14)0.05290 (8)
N10.7787 (2)1.06178 (12)0.85616 (10)0.0397 (3)
C10.8014 (4)1.15508 (19)0.92125 (17)0.0613 (5)
H1A0.73281.21500.89470.074*
H1B0.93891.17200.92790.074*
H1C0.74711.13830.98300.074*
C20.8857 (3)0.9680 (2)0.89734 (18)0.0578 (5)
H2A0.87060.90810.85540.069*
H2B0.83170.95120.95910.069*
H2C1.02320.98480.90390.069*
C310.7883 (5)1.1763 (3)0.70577 (19)0.0808 (8)
H31A0.85691.18450.64600.097*
H31B0.80251.23990.74320.097*
H31C0.65091.16350.69360.097*
C30.8734 (3)1.08411 (19)0.75980 (15)0.0526 (5)
H3A1.01301.09720.76980.063*
H3B0.86171.02100.72030.063*
C40.5616 (2)1.03466 (14)0.84108 (12)0.0373 (3)
H4A0.49331.09820.81970.045*
H4B0.55180.98240.79020.045*
C410.4578 (2)0.99204 (13)0.92838 (12)0.0368 (3)
C420.3755 (3)1.05941 (16)0.99624 (14)0.0483 (4)
H420.38791.13260.98920.058*
C430.2748 (4)1.0181 (2)1.07459 (15)0.0617 (5)
H430.22221.06361.12050.074*
C440.2528 (3)0.9094 (2)1.08438 (16)0.0645 (6)
H440.18600.88171.13700.077*
C450.3293 (4)0.84284 (19)1.01657 (18)0.0619 (6)
H450.31260.76981.02290.074*
C460.4319 (3)0.88285 (15)0.93829 (16)0.0477 (4)
H460.48320.83670.89250.057*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Br10.06094 (12)0.04546 (10)0.05230 (11)0.00357 (9)0.00416 (9)0.00747 (8)
N10.0369 (6)0.0416 (7)0.0405 (6)−0.0039 (6)−0.0001 (6)−0.0024 (5)
C10.0611 (12)0.0599 (12)0.0629 (12)−0.0199 (11)0.0056 (12)−0.0207 (10)
C20.0422 (9)0.0646 (13)0.0667 (13)0.0038 (9)−0.0115 (9)0.0112 (10)
C310.0638 (13)0.106 (2)0.0727 (15)0.0084 (16)0.0168 (13)0.0409 (14)
C30.0452 (9)0.0642 (12)0.0482 (10)−0.0012 (9)0.0100 (8)0.0015 (9)
C40.0357 (7)0.0384 (8)0.0378 (7)−0.0008 (6)−0.0014 (6)0.0000 (6)
C410.0356 (7)0.0363 (8)0.0386 (7)−0.0027 (6)−0.0026 (6)0.0018 (6)
C420.0509 (9)0.0470 (10)0.0470 (9)−0.0018 (8)0.0061 (8)−0.0034 (8)
C430.0592 (11)0.0815 (15)0.0444 (9)−0.0056 (12)0.0091 (10)−0.0051 (10)
C440.0544 (13)0.0901 (17)0.0489 (10)−0.0140 (11)−0.0012 (8)0.0251 (11)
C450.0603 (13)0.0531 (11)0.0722 (14)−0.0119 (10)−0.0057 (11)0.0228 (10)
C460.0484 (9)0.0363 (8)0.0584 (10)−0.0033 (7)−0.0020 (9)0.0034 (8)
Geometric parameters (Å, °) top
Br1—N14.4393 (16)C3—H3B0.970
N1—C11.492 (2)C4—C411.505 (2)
N1—C21.499 (3)C4—H4A0.970
N1—C31.515 (2)C4—H4B0.970
N1—C41.525 (2)C41—C421.387 (3)
C1—H1A0.960C41—C461.392 (2)
C1—H1B0.960C42—C431.389 (3)
C1—H1C0.960C42—H420.930
C2—H2A0.960C43—C441.382 (4)
C2—H2B0.960C43—H430.930
C2—H2C0.960C44—C451.365 (4)
C31—C31.498 (3)C44—H440.930
C31—H31A0.960C45—C461.388 (3)
C31—H31B0.960C45—H450.930
C31—H31C0.960C46—H460.930
C3—H3A0.970
C1—N1—C2109.66 (17)C31—C3—H3A108.5
C1—N1—C3110.47 (16)N1—C3—H3A108.5
C2—N1—C3106.30 (16)C31—C3—H3B108.5
C1—N1—C4111.07 (16)N1—C3—H3B108.5
C2—N1—C4110.08 (15)H3A—C3—H3B107.5
C3—N1—C4109.15 (14)C41—C4—N1114.79 (13)
C1—N1—Br168.95 (13)C41—C4—H4A108.6
C2—N1—Br1158.26 (12)N1—C4—H4A108.6
C3—N1—Br193.99 (11)C41—C4—H4B108.6
C4—N1—Br154.22 (8)N1—C4—H4B108.6
N1—C1—H1A109.5H4A—C4—H4B107.5
N1—C1—H1B109.5C42—C41—C46119.00 (18)
H1A—C1—H1B109.5C42—C41—C4121.45 (15)
N1—C1—H1C109.5C46—C41—C4119.40 (16)
H1A—C1—H1C109.5C41—C42—C43120.3 (2)
H1B—C1—H1C109.5C41—C42—H42119.8
N1—C2—H2A109.5C43—C42—H42119.8
N1—C2—H2B109.5C44—C43—C42120.1 (2)
H2A—C2—H2B109.5C44—C43—H43120.0
N1—C2—H2C109.5C42—C43—H43120.0
H2A—C2—H2C109.5C45—C44—C43119.8 (2)
H2B—C2—H2C109.5C45—C44—H44120.1
C3—C31—H31A109.5C43—C44—H44120.1
C3—C31—H31B109.5C44—C45—C46120.8 (2)
H31A—C31—H31B109.5C44—C45—H45119.6
C3—C31—H31C109.5C46—C45—H45119.6
H31A—C31—H31C109.5C45—C46—C41119.9 (2)
H31B—C31—H31C109.5C45—C46—H46120.0
C31—C3—N1115.22 (18)C41—C46—H46120.0
C1—N1—C3—C31−60.9 (3)N1—C4—C41—C46−98.94 (19)
C2—N1—C3—C31−179.8 (2)C46—C41—C42—C432.2 (3)
C4—N1—C3—C3161.5 (2)C4—C41—C42—C43177.88 (19)
Br1—N1—C3—C318.1 (2)C41—C42—C43—C44−1.2 (3)
C1—N1—C4—C41−68.2 (2)C42—C43—C44—C45−0.4 (4)
C2—N1—C4—C4153.4 (2)C43—C44—C45—C460.9 (4)
C3—N1—C4—C41169.73 (15)C44—C45—C46—C410.1 (3)
Br1—N1—C4—C41−109.45 (15)C42—C41—C46—C45−1.6 (3)
N1—C4—C41—C4285.4 (2)C4—C41—C46—C45−177.40 (18)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C1—H1A···Br10.963.344.144 (3)143
C4—H4A···Br10.972.813.757 (2)164
C42—H42···Br10.933.263.950 (2)132
C31—H31C···Br10.963.363.953 (3)122
C2—H2A···Br1i0.962.963.850 (3)154
C4—H4B···Br1i0.972.963.832 (2)151
C3—H3B···Br1i0.973.083.950 (2)151
C3—H3A···Br1ii0.973.193.959 (2)138
C1—H1C···Br1iii0.962.993.766 (2)139
C2—H2C···Cg1ii0.962.693.526145
Symmetry codes: (i) −x+1, y−1/2, −z+3/2; (ii) x+1, y, z; (iii) x+1/2, −y+5/2, −z+2.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C4—H4A···Br10.972.813.757 (2)164
C2—H2A···Br1i0.962.963.850 (3)154
C4—H4B···Br1i0.972.963.832 (2)151
C3—H3B···Br1i0.973.083.950 (2)151
C3—H3A···Br1ii0.973.193.959 (2)138
C1—H1C···Br1iii0.962.993.766 (2)139
C2—H2C···Cg1ii0.962.693.526145
Symmetry codes: (i) −x+1, y−1/2, −z+3/2; (ii) x+1, y, z; (iii) x+1/2, −y+5/2, −z+2.
Acknowledgements top

The authors thank the Joint X-ray Laboratory, Faculty of Chemistry, and SLAFiBS, Jagiellonian University, for making the Nonius KappaCCD diffractometer available.

references
References top

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