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n-Un­decyl­ammonium bromide crystallizes from solution as the monohydrate, C11H23NH3+·Br-·H2O, the structure containing alternating ionic and hydro­carbon layers. The water mol­ecules are incorporated into the ionic layer and they interact, via hydrogen bonds, with the bromide anions and the terminal ammonium groups. The non-polar methyl­ene chains are fully extended with all-trans conformations. The mol­ecules pack as parallel and interdigitated cyl­inders, roughly perpendicular to the layers.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536803004859/wn6139sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536803004859/wn6139Isup2.hkl
Contains datablock I

CCDC reference: 209956

Key indicators

  • Single-crystal X-ray study
  • T = 293 K
  • Mean [sigma](C-C) = 0.006 Å
  • R factor = 0.044
  • wR factor = 0.123
  • Data-to-parameter ratio = 28.7

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

General Notes

FORMU_01 There is a discrepancy between the atom counts in the _chemical_formula_sum and _chemical_formula_moiety. This is usually due to the moiety formula being in the wrong format. Atom count from _chemical_formula_sum: C11 H28 Br1 N1 O1 Atom count from _chemical_formula_moiety:

Comment top

Long-chain n-alkylammonium halides are widely used as surfactants (Aratono et al., 1998; Törnblom et al., 2000) and as models for biological membranes (Ringsdorf et al., 1988). They exhibit polymorphism at room temperature (Gilson et al., 1976; Schenk et al., 1989; Terreros et al., 2000) and a complex sequence of solid–solid phase transitions at higher temperatures (Tsau & Gilson, 1968; Kind et al., 1982; Reynhardt et al., 1998). Only four crystal structures of n-alkylammonium halides have been reported previously. They are the three anhydrous compounds n-decylammonium chloride (C10H21NH3+·Cl; Schenk & Chapuis, 1986; Pinto et al., 1987), n-dodecylammonium chloride (C12H25NH3+·Cl; Pinto et al., 1987; Silver et al., 1995) and n-dodecylammonium bromide (C12H25NH3+·Br; Lundén, 1974), and the solvate (sometimes also called a pseudo-polymorph) n-undecylammonium chloride monohydrate (C11H23NH3+·Cl·H2O; Silver et al., 1996). They all exhibit alternating hydrocarbon and ionic layers, with hydrogen bonding in the ionic layer.

In this study, we have established that n-undecylammonium bromide monohydrate, C11H23NH3+·Br·H2O, (I), is isostructural with n-undecylammonium chloride monohydrate, C11H23NH3+·Cl·H2O, (Silver et al., 1996). The crystal structure of the chloride has to be transformed, however, to be consistent with P21/c symmetry, as it was reported in space group P21/a, with a = 7.701 (2) Å, b = 40.020 (5) Å, c = 4.6437 (6) Å and β = 107.34 (1)°. The two monohydrate structures exhibit similar molecular conformations and crystal packing. The only obvious effect of the change in anion is to expand the bromide cell, by an increase in all three unit-cell lengths. The cell volumes of the chloride and bromide are 1366.1 (4) and 1473 (3) Å3, respectively, indicating that a volume increase of approximately 27 Å3 is required to accommodate the larger bromide anion.

The molecular structure of (I) is illustrated in Fig. 1. The methylene chain has the extended all-trans conformation, but it is slightly curved in the vicinity of the ammonium group, probably to accommodate the hydrogen-bonding interactions. The extent of the curvature is illustrated by the deviation from planarity of the carbon backbone of the molecule, which is found to be dependent on the size of the anion. In both monohydrate structures, atoms C2–C11 are coplanar, while N and C1 are displaced significantly from these ideal carbon zigzag planes; the r.m.s. deviations of the fitted atoms from the least-squares planes are 0.029 and 0.026 Å for the chloride and the bromide, respectively. Atoms N and C1 are out of plane by 0.392 and 0.341 Å for the chloride, and 0.314 (5) and 0.317 (5) Å for the bromide, respectively. An alternative measure of the curvature is the deviation of torsion angles from their ideal values. Only torsion angle C1—C2—C3—C4 deviates significantly from 180°, with a value of 170.0 (1)° for the chloride and 170.8 (3)° for the bromide.

The interdigitated packing displayed by (I) is illustrated in Fig. 2. In the hydrocarbon layer, the chains are parallel to one another and interact via van der Waals forces. The molecular plane (calculated through atoms C2–C11) is at an angle of 87.07 (8)° to the ionic plane, indicating that the molecules are almost perpendicular to the layers. The type of packing exhibited by the methylene chains (C2–C11) can be classified as the polymethylene subcell `M2 perpendicular' (Segerman, 1965), with subcell parameters as = 4.809 Å, bs = 8.050 Å, cs ~2.54 Å, γs = 109.47° and space group A2/m, with cs chosen to be in the direction of the long axis. The calculated cross-sectional area per chain, 18.3 Å2, indicates dense chain packing.

The ionic layer of (I) consists of ammonium groups, bromide anions and water molecules, all interacting via hydrogen bonds (Table 1 and Fig. 2). Each ammonium group is hydrogen bonded to two bromide anions and one O atom of a water molecule. Each water molecule is, in turn, hydrogen bonded to two bromide anions. The hydrogen-bonding N···halide and O···halide distances are shorter for the chloride than for the bromide [3.209 (1) and 3.235 (2) Å compared to 3.366 (4) and 3.392 (5) Å], but the distances of the N···O interaction, where the anion does not play a role, are similar, 2.845 (2) and 2.828 (5) Å. Likewise, the water-to-halide-anion interactions are shorter for the chloride than for the bromide [3.180 (1) and 3.226 (1) Å compared to 3.535 (4) and 3.384 (4) Å].

A property that n-undecylammonium bromide shares with other n-alkylammonium halides is that of polymorphism. A different crystal form of the bromide, as characterized by differential scanning calorimetry (DSC), crystallizes from the melt, as opposed to the crystallization from solvent of the monohydrate reported here. The hydrate exhibits three solid–solid phase transitions on heating before melting, as determined by DSC measurements. The transitions were named according to the established phase sequence nomenclature reported for n-alkylammonium chlorides (Schenk, 1986), except that we have called the initial monohydrate phase the m phase. The following transition temperatures were observed: m phase to β phase, 319.86 K; β phase to α phase, 341.52 K; α phase to liquid crystal phase, 467.60 K and liquid crystal phase to the melt, 536.96 K.

Experimental top

n-Undecylammonium bromide was prepared by the addition of HBr to an ethanol solution of n-undecylamine. The resulting precipitate was filtered off and recrystallized several times from chloroform. Single crystals were obtained by slow evaporation of a chloroform solution at room temperature. DSC curves were measured on a Mettler–Toledo 822 instrument. The temperature scale and heat-flow values were calibrated to the known values of indium and zinc. The DSC samples, weighing between 1 and 2 mg, were sealed in 40 µl aluminium pans with holes punched into the lids to prevent pressure build-up due to desolvation. The samples were heated from room temperature at a constant rate of 5 K min−1.

Refinement top

The H atoms of the water molecule were fixed in position at a distance of 0.82 Å from the O atom on the O.·Br vectors. All other H atoms were positioned geometrically and refined using a riding model, with rotation in the case of the terminal ammonium and methyl groups.

Computing details top

Data collection: SMART-NT (Bruker, 1998); cell refinement: SAINT-Plus (Bruker, 1999); data reduction: XPREP (Bruker, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), illustrating the hydrogen bonds (dotted lines) between the N atom, the anion, and the water of crystallization. Displacement ellipsoids are drawn at the 50% probability level (ORTEP-3; Farrugia, 1997).
[Figure 2] Fig. 2. A packing diagram of (I), viewed down the a axis, showing the interdigitated packing of the molecules and the alternating ionic and hydrocarbon layers.
n-undecylammonium bromide monohydrate top
Crystal data top
C11H26N+Br·H2F(000) = 576
Mr = 270.25Dx = 1.219 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 1024 reflections
a = 4.809 (6) Åθ = 3.0–22.4°
b = 40.353 (5) ŵ = 2.77 mm1
c = 7.882 (9) ÅT = 293 K
β = 105.65 (2)°Thin plate, colourless
V = 1473 (3) Å30.11 × 0.09 × 0.03 mm
Z = 4
Data collection top
Bruker SMART CCD area-detector
diffractometer
3647 independent reflections
Radiation source: fine-focus sealed tube1923 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.060
ω scansθmax = 28.3°, θmin = 1.0°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
h = 66
Tmin = 0.751, Tmax = 0.922k = 5333
10404 measured reflectionsl = 1010
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.044Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.123H-atom parameters constrained
S = 0.94 w = 1/[σ2(Fo2) + (0.0571P)2]
where P = (Fo2 + 2Fc2)/3
3647 reflections(Δ/σ)max = 0.003
127 parametersΔρmax = 0.36 e Å3
0 restraintsΔρmin = 0.54 e Å3
Crystal data top
C11H26N+Br·H2V = 1473 (3) Å3
Mr = 270.25Z = 4
Monoclinic, P21/cMo Kα radiation
a = 4.809 (6) ŵ = 2.77 mm1
b = 40.353 (5) ÅT = 293 K
c = 7.882 (9) Å0.11 × 0.09 × 0.03 mm
β = 105.65 (2)°
Data collection top
Bruker SMART CCD area-detector
diffractometer
3647 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
1923 reflections with I > 2σ(I)
Tmin = 0.751, Tmax = 0.922Rint = 0.060
10404 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0440 restraints
wR(F2) = 0.123H-atom parameters constrained
S = 0.94Δρmax = 0.36 e Å3
3647 reflectionsΔρmin = 0.54 e Å3
127 parameters
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
Br0.20924 (9)0.223762 (11)0.47014 (6)0.04986 (17)
N0.6890 (7)0.21804 (7)0.8729 (5)0.0470 (9)
H12A0.80260.23570.88290.070*
H12B0.63940.21510.97270.070*
H12C0.53090.22110.78460.070*
C10.8460 (8)0.18836 (9)0.8368 (5)0.0438 (10)
H1A1.02010.18540.93210.053*
H1B0.90290.19180.72900.053*
C20.6629 (8)0.15740 (9)0.8183 (5)0.0414 (9)
H2A0.48750.16050.72410.050*
H2B0.60830.15370.92670.050*
C30.8226 (9)0.12716 (9)0.7788 (5)0.0462 (10)
H3A1.01210.12630.86220.055*
H3B0.84970.12940.66180.055*
C40.6653 (8)0.09472 (9)0.7884 (5)0.0441 (10)
H4A0.63450.09280.90460.053*
H4B0.47710.09550.70350.053*
C50.8231 (9)0.06420 (10)0.7529 (5)0.0465 (10)
H5A1.01470.06400.83410.056*
H5B0.84550.06560.63450.056*
C60.6734 (9)0.03188 (10)0.7709 (5)0.0469 (10)
H6A0.48160.03220.69000.056*
H6B0.65100.03050.88940.056*
C70.8284 (9)0.00102 (9)0.7356 (5)0.0456 (10)
H7A0.85050.00240.61710.055*
H7B1.02040.00070.81640.055*
C80.6812 (8)0.03105 (9)0.7537 (5)0.0438 (10)
H8A0.48900.03070.67320.053*
H8B0.65970.03240.87240.053*
C90.8355 (9)0.06181 (10)0.7179 (5)0.0473 (10)
H9A1.02770.06210.79850.057*
H9B0.85720.06040.59930.057*
C100.6876 (10)0.09419 (10)0.7359 (6)0.0561 (12)
H10A0.66860.09590.85500.067*
H10B0.49450.09390.65640.067*
C110.8425 (11)0.12445 (11)0.6973 (7)0.0733 (14)
H11A0.73620.14390.71140.110*
H11B1.03220.12540.77740.110*
H11C0.85780.12340.57850.110*
O0.5917 (7)0.19690 (8)0.1941 (4)0.0679 (9)
H13A0.74580.20360.26250.050*
H13B0.50240.20350.26210.050*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Br0.0474 (2)0.0507 (3)0.0511 (3)0.0058 (2)0.01263 (18)0.0056 (2)
N0.052 (2)0.033 (2)0.056 (2)0.0047 (15)0.0135 (17)0.0035 (16)
C10.046 (2)0.032 (2)0.054 (2)0.0043 (18)0.0152 (19)0.0056 (19)
C20.046 (2)0.031 (2)0.049 (2)0.0030 (17)0.0163 (19)0.0037 (18)
C30.056 (3)0.038 (2)0.048 (2)0.0003 (19)0.021 (2)0.0013 (19)
C40.048 (2)0.035 (2)0.051 (2)0.0010 (18)0.0159 (19)0.0029 (19)
C50.050 (2)0.040 (2)0.052 (2)0.0018 (19)0.019 (2)0.004 (2)
C60.052 (2)0.041 (2)0.051 (2)0.0020 (19)0.020 (2)0.002 (2)
C70.055 (2)0.036 (2)0.049 (2)0.0037 (19)0.020 (2)0.0002 (19)
C80.047 (2)0.040 (2)0.048 (2)0.0005 (18)0.0201 (19)0.0016 (19)
C90.052 (2)0.040 (2)0.051 (2)0.0045 (19)0.016 (2)0.000 (2)
C100.070 (3)0.039 (3)0.061 (3)0.004 (2)0.019 (2)0.000 (2)
C110.091 (4)0.042 (3)0.090 (4)0.003 (3)0.030 (3)0.009 (3)
O0.072 (2)0.078 (2)0.0582 (18)0.0052 (18)0.0254 (16)0.0162 (17)
Geometric parameters (Å, º) top
N—C11.484 (5)C6—H6A0.9700
N—H12A0.8900C6—H6B0.9700
N—H12B0.8900C7—C81.500 (5)
N—H12C0.8900C7—H7A0.9700
C1—C21.513 (5)C7—H7B0.9700
C1—H1A0.9700C8—C91.511 (5)
C1—H1B0.9700C8—H8A0.9700
C2—C31.518 (5)C8—H8B0.9700
C2—H2A0.9700C9—C101.513 (6)
C2—H2B0.9700C9—H9A0.9700
C3—C41.524 (5)C9—H9B0.9700
C3—H3A0.9700C10—C111.504 (6)
C3—H3B0.9700C10—H10A0.9700
C4—C51.512 (5)C10—H10B0.9700
C4—H4A0.9700C11—H11A0.9600
C4—H4B0.9700C11—H11B0.9600
C5—C61.515 (5)C11—H11C0.9600
C5—H5A0.9700O—H13A0.836
C5—H5B0.9700O—H13B0.817
C6—C71.515 (5)
C1—N—H12A109.5C5—C6—H6A108.5
C1—N—H12B109.5C7—C6—H6A108.5
H12A—N—H12B109.5C5—C6—H6B108.5
C1—N—H12C109.5C7—C6—H6B108.5
H12A—N—H12C109.5H6A—C6—H6B107.5
H12B—N—H12C109.5C8—C7—C6115.0 (3)
N—C1—C2111.8 (3)C8—C7—H7A108.5
N—C1—H1A109.3C6—C7—H7A108.5
C2—C1—H1A109.3C8—C7—H7B108.5
N—C1—H1B109.3C6—C7—H7B108.5
C2—C1—H1B109.3H7A—C7—H7B107.5
H1A—C1—H1B107.9C7—C8—C9115.0 (3)
C1—C2—C3111.7 (3)C7—C8—H8A108.5
C1—C2—H2A109.3C9—C8—H8A108.5
C3—C2—H2A109.3C7—C8—H8B108.5
C1—C2—H2B109.3C9—C8—H8B108.5
C3—C2—H2B109.3H8A—C8—H8B107.5
H2A—C2—H2B107.9C8—C9—C10115.1 (4)
C2—C3—C4113.3 (3)C8—C9—H9A108.5
C2—C3—H3A108.9C10—C9—H9A108.5
C4—C3—H3A108.9C8—C9—H9B108.5
C2—C3—H3B108.9C10—C9—H9B108.5
C4—C3—H3B108.9H9A—C9—H9B107.5
H3A—C3—H3B107.7C11—C10—C9114.3 (4)
C5—C4—C3114.2 (3)C11—C10—H10A108.7
C5—C4—H4A108.7C9—C10—H10A108.7
C3—C4—H4A108.7C11—C10—H10B108.7
C5—C4—H4B108.7C9—C10—H10B108.7
C3—C4—H4B108.7H10A—C10—H10B107.6
H4A—C4—H4B107.6C10—C11—H11A109.5
C4—C5—C6114.2 (3)C10—C11—H11B109.5
C4—C5—H5A108.7H11A—C11—H11B109.5
C6—C5—H5A108.7C10—C11—H11C109.5
C4—C5—H5B108.7H11A—C11—H11C109.5
C6—C5—H5B108.7H11B—C11—H11C109.5
H5A—C5—H5B107.6H13A—O—H13B90.1
C5—C6—C7114.9 (3)
N—C1—C2—C3179.2 (3)C5—C6—C7—C8179.9 (3)
C1—C2—C3—C4170.8 (3)C6—C7—C8—C9179.8 (3)
C2—C3—C4—C5178.9 (3)C7—C8—C9—C10180.0 (4)
C3—C4—C5—C6177.2 (3)C8—C9—C10—C11179.2 (4)
C4—C5—C6—C7179.9 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N—H12A···Bri0.892.503.366 (4)165
N—H12B···Oii0.891.962.828 (5)164
N—H12C···Br0.892.553.392 (5)159
O—H13A···Briii0.842.5173.353 (4)180
O—H13B···Br0.822.5673.384 (4)179
Symmetry codes: (i) x+1, y+1/2, z+1/2; (ii) x, y, z+1; (iii) x+1, y, z.

Experimental details

Crystal data
Chemical formulaC11H26N+Br·H2
Mr270.25
Crystal system, space groupMonoclinic, P21/c
Temperature (K)293
a, b, c (Å)4.809 (6), 40.353 (5), 7.882 (9)
β (°) 105.65 (2)
V3)1473 (3)
Z4
Radiation typeMo Kα
µ (mm1)2.77
Crystal size (mm)0.11 × 0.09 × 0.03
Data collection
DiffractometerBruker SMART CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 1996)
Tmin, Tmax0.751, 0.922
No. of measured, independent and
observed [I > 2σ(I)] reflections
10404, 3647, 1923
Rint0.060
(sin θ/λ)max1)0.667
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.044, 0.123, 0.94
No. of reflections3647
No. of parameters127
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.36, 0.54

Computer programs: SMART-NT (Bruker, 1998), SAINT-Plus (Bruker, 1999), XPREP (Bruker, 1999), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N—H12A···Bri0.892.503.366 (4)165
N—H12B···Oii0.891.962.828 (5)164
N—H12C···Br0.892.553.392 (5)159
O—H13A···Briii0.842.5173.353 (4)180
O—H13B···Br0.822.5673.384 (4)179
Symmetry codes: (i) x+1, y+1/2, z+1/2; (ii) x, y, z+1; (iii) x+1, y, z.
 

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