Acta Cryst. (2008). E64, o2236 [ doi:10.1107/S1600536808034843 ]
The structure of the title compound, C6H16N+·Br-, was determined at low temperature and the cell dimensions were comparable to those reported for room-temperature studies [James, Cameron, Knop, Newman & Falp, (1985). Can. J. Chem. 63, 1750-1758]. Initial analysis of the data led to the assignment of P31c as the space group rather than P63mc as reported for the room-temperature structure. Careful examination of the appropriate |Fo| values in the low-temperature data showed that the equalities |F(
kl)| = |F(h
l)| and |F(hkl)| = |F(hk
)| did not hold at low temperature, confirming P31c as the appropriate choice of space group. As a consequence of this choice, the N atom sat on a threefold axis and the ethyl arms were not disordered as observed at room temperature. The crystal studied was an inversion twin with a 0.68 (3):0.32 (3) domain ratio.
The title compound, (I), was prepared as a by-product in a reaction to form (2,5-oxo-1-pyrrolidyl)oxy-2-bromo-2-methylpropionate by the method of Lecolley et al. (2004). X-Ray quality crystals were grown by the slow evaporation of an acetonitrile solution.
All H-atoms bound to carbon were refined using a riding model with d(C—H) = 0.96 Å, Uiso=1.5Ueq (C) for the methyl CH H atoms and d(C—H) = 0.97 Å, Uiso=1.2Ueq (C) for the methylene CH H atoms. The H-atom bound to nitrogen was refined using a riding model with d(N—H) = 0.87 Å, Uiso=1.2Ueq (N).
Data collection: APEX2 (Bruker, 2006); cell refinement: APEX2 (Bruker, 2006) and SAINT (Bruker, 2006); data reduction: SAINT (Bruker, 2006); program(s) used to solve structure: SIR97 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).
![[Figure 1]](./pv2113fig1thm.gif)
| Fig. 1. A view of the molecule of (I) showing the atom numbering with displacement ellipsoids drawn at the 50% probability level. Symmetry codes: (i) -x+y, -x+1, z; (ii) -y+1, x-y+1, z. |
![[Figure 2]](./pv2113fig2thm.gif)
| Fig. 2. Packing diagram of (I) in the ab plane. |
| C6H16N+·Br− | Dx = 1.367 Mg m−3 |
| Mr = 182.10 | Mo Kα radiation, λ = 0.71073 Å |
| Trigonal, P31c | Cell parameters from 7729 reflections |
| Hall symbol: P 3 -2c | θ = 2.8–27.5° |
| a = 8.3589 (2) Å | µ = 4.56 mm−1 |
| c = 7.3125 (2) Å | T = 90 K |
| V = 442.48 (1) Å3 | Rod, colourless |
| Z = 2 | 0.27 × 0.11 × 0.10 mm |
| F(000) = 188 |
| Bruker APEXII CCD area-detector diffractometer | 555 independent reflections |
| Radiation source: fine-focus sealed tube | 550 reflections with I > 2σ(I) |
| graphite | Rint = 0.026 |
| φ and ω scans | θmax = 25.5°, θmin = 4.0° |
| Absorption correction: multi-scan (SADABS; Bruker, 2004) | h = −10→10 |
| Tmin = 0.450, Tmax = 0.633 | k = −10→10 |
| 8583 measured reflections | l = −8→8 |
| Refinement on F2 | Secondary atom site location: difference Fourier map |
| Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
| R[F2 > 2σ(F2)] = 0.020 | H-atom parameters constrained |
| wR(F2) = 0.058 | w = 1/[σ2(Fo2) + (0.0371P)2 + 0.4873P] where P = (Fo2 + 2Fc2)/3 |
| S = 1.24 | (Δ/σ)max < 0.001 |
| 555 reflections | Δρmax = 0.39 e Å−3 |
| 23 parameters | Δρmin = −0.39 e Å−3 |
| 1 restraint | Absolute structure: Flack (1983), 273 Friedel pairs |
| Primary atom site location: structure-invariant direct methods | Flack parameter: 0.32 (3) |
| C6H16N+·Br− | Z = 2 |
| Mr = 182.10 | Mo Kα radiation |
| Trigonal, P31c | µ = 4.56 mm−1 |
| a = 8.3589 (2) Å | T = 90 K |
| c = 7.3125 (2) Å | 0.27 × 0.11 × 0.10 mm |
| V = 442.48 (1) Å3 |
| Bruker APEXII CCD area-detector diffractometer | 555 independent reflections |
| Absorption correction: multi-scan (SADABS; Bruker, 2004) | 550 reflections with I > 2σ(I) |
| Tmin = 0.450, Tmax = 0.633 | Rint = 0.026 |
| 8583 measured reflections | θmax = 25.5° |
| R[F2 > 2σ(F2)] = 0.020 | H-atom parameters constrained |
| wR(F2) = 0.058 | Δρmax = 0.39 e Å−3 |
| S = 1.24 | Δρmin = −0.39 e Å−3 |
| 555 reflections | Absolute structure: Flack (1983), 273 Friedel pairs |
| 23 parameters | Flack parameter: 0.32 (3) |
| 1 restraint |
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. The crystal studied was an inversion twin with a 0.68 (3);0.32 (3) domain ratio. |
| x | y | z | Uiso*/Ueq | ||
| C1 | 0.1624 (6) | 0.8395 (6) | 0.4111 (5) | 0.0323 (9) | |
| H1A | 0.1536 | 0.8181 | 0.2815 | 0.048* | |
| H1B | 0.2690 | 0.9571 | 0.4373 | 0.048* | |
| H1C | 0.0533 | 0.8389 | 0.4534 | 0.048* | |
| N1 | 0.3333 | 0.6667 | 0.4505 (6) | 0.0168 (12) | |
| H1 | 0.3333 | 0.6667 | 0.3260 | 0.020* | |
| C2 | 0.1789 (5) | 0.6982 (5) | 0.5011 (5) | 0.0232 (7) | |
| H2A | 0.0644 | 0.5830 | 0.4820 | 0.028* | |
| H2B | 0.1884 | 0.7240 | 0.6312 | 0.028* | |
| Br1 | 0.6667 | 0.3333 | 0.5017 | 0.01786 (16) |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| C1 | 0.034 (2) | 0.038 (2) | 0.035 (2) | 0.026 (2) | −0.0004 (16) | −0.0026 (17) |
| N1 | 0.0162 (14) | 0.0162 (14) | 0.018 (3) | 0.0081 (7) | 0.000 | 0.000 |
| C2 | 0.0168 (15) | 0.0228 (14) | 0.0293 (17) | 0.0095 (12) | 0.0004 (14) | 0.0001 (16) |
| Br1 | 0.01867 (19) | 0.01867 (19) | 0.0162 (2) | 0.00933 (9) | 0.000 | 0.000 |
| C1—C2 | 1.418 (5) | N1—C2i | 1.488 (4) |
| C1—H1A | 0.9600 | N1—C2ii | 1.488 (4) |
| C1—H1B | 0.9600 | N1—H1 | 0.9100 |
| C1—H1C | 0.9600 | C2—H2A | 0.9700 |
| N1—C2 | 1.488 (4) | C2—H2B | 0.9700 |
| C2—C1—H1A | 109.5 | C2—N1—H1 | 104.4 |
| C2—C1—H1B | 109.5 | C2i—N1—H1 | 104.4 |
| H1A—C1—H1B | 109.5 | C2ii—N1—H1 | 104.4 |
| C2—C1—H1C | 109.5 | C1—C2—N1 | 119.1 (3) |
| H1A—C1—H1C | 109.5 | C1—C2—H2A | 107.5 |
| H1B—C1—H1C | 109.5 | N1—C2—H2A | 107.5 |
| C2—N1—C2i | 114.03 (18) | C1—C2—H2B | 107.5 |
| C2—N1—C2ii | 114.03 (18) | N1—C2—H2B | 107.5 |
| C2i—N1—C2ii | 114.03 (18) | H2A—C2—H2B | 107.0 |
| Symmetry codes: (i) −x+y, −x+1, z; (ii) −y+1, x−y+1, z. |
We acknowledge the award of a John Edmond Postgraduate Scholarship in Chemistry (NHM) and thank the University of Otago Research Committee and the New Economic Research Fund (grant No UOO-X0404 from the New Zealand Foundation of Research Science and Technology) for financial support.
Altomare, A., Cascarano, G., Giacovazzo, C. & Guagliardi, A. (1993). J. Appl. Cryst. 26, 343–350.
Bruker (2004). SADABS. Bruker AXS Inc., Madison, Wisconsin, USA..
Bruker (2006). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.
Flack, H. D. (1983). Acta Cryst. A39, 876–881.
James, M. A., Cameron, S. T., Knop, O., Neuman, M. & Falk, M. (1985). Can. J. Chem. 63, 1750–1758.
Lecolley, F., Tao, L., Mantovani, G., Durkin, I., Lautru, S. & Haddleton, D. M. (2004). Chem. Commun. pp. 2026–2027.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.
The title compound, (I), was isolated as a by-product in a reaction to form (2,5-oxo-1-pyrrolidyl)oxy-2-bromo-2-methylpropionate (Lecolley et al., 2004). A view of the structure of (I) is presented in Fig. 1. The crystal structures of (I) and the other halide analogues at ambient temperature have previously been described by James et al. (1985). Unlike previous work, analysis of our low-temperature data showed that (I) crystallized in the space group P31c with the ethyl chains in fixed locations. The e.s.d.'s of the positional parameters and the R factors were significantly lower than those reported for the room temperature structure. The packing of (I) (Fig. 2) at low temperature is very similar to that of the room temperature disordered structure. James et al. (1985) also analysed the IR spectra of these compounds in some detail.