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Acta Cryst. (2008). E64, o637    [ doi:10.1107/S1600536808005229 ]

1-Methyl-1-propylpyrrolidinium chloride

P. M. Dean, J. M. Pringle and D. R. MacFarlane

Abstract top

The aymmetric unit of the title compound, C8H18N+·Cl-, consists of one crystallographically independent 1-methyl-1-propylpyrrolidinium cation and one chloride anion, both of which lie in general positions. Minor hydrogen-bonded C-H...Cl interactions occur. However, no classical hydrogen bonding is observed.

Comment top

The title compound, (I), is commonly used as a precursor in ionic liquid synthesis (MacFarlane et al., 1999, Sun et al., 2003). Pyrrolidinium-based ionic liquids have been a subject of intense investigation recently (Henderson et al., 2006), whereby with understanding of the fundamental molecular-level interactions, a desired product with predicted physico-chemical properites could be designed. Additionally, a particular emphasis has been placed on whether hydrogen bonding occurs between the cation and a potential electron-pair donor (hydrogen bond acceptor) and its influence on the ionic liquids' overall properties. This paper briefly reports the structural determination and analysis of 1-methyl-1-propyl pyrrolidinium chloride (Figure 1).

The bond distances and angles of the pyrrolidinium cation are all within normal ranges (as is tabulated in Allen et al., 1987), with the propyl substituent adopting the energetically preferred anti conformation (torsional angle N1—C6—C7—C8: -177.0 (2) °) and the ring adopting the energetically preferred envelope (Cs) conformation. The extended structure packs in layers of groups of anions and cations (Figure 2) which are interconnected by an extended network of weak hydrogen bonds (C—H···Cl interactions), where each cation is hydrogen bonded to four anions and each anion is weakly hydrogen bonded to four cations [C1—H1B···Cl1i [3.607 (2) Å], C2—H2A···Cl1ii [3.630 (2) Å], C5— H5A ··· Cl1 [3.648 (1) Å], C5—H5C···Cl1iii [3.656 (1) Å], C6—H6A···Cl1i [3.672 (2) Å] and C6— H6B···Cl1 [3.666 (1) Å] (symmetry operators: i=1/2 - x,3/2 - y,1/2 + z; ii=1 - x,y,1/2 - z; iii=x,2 - y,1/2 + z) -see Table 1]. Analysis of the salts' Hirshfeld surface, reveals that the short range inter-cationic H—H intermolecular contact contribution to the Hirshfeld surface area predominates (McKinnon et al., 2007).

Related literature top

For bond-length data, see: Allen et al. (1987). For comparative thermal and crystallographic analysis of four crystallized N-alkyl-N-methylpyrrolidinium and piperidinium bis(trifluoromethanesulfonyl)imide salts and an insight into why these salts form room-temperature ionic liquids, see: Henderson et al. (2006). For the synthesis and analysis of N-butyl-N-methyl pyrrolidinium chloride, an analogue of the title compound, see: Lancaster et al. (2002). MacFarlane et al. (1999) describes the first synthesis and analysis of the new pyrrolidinium family of molten salts. McKinnon et al. (2007) describes the quantitative comparison of intermolecular interactions using Hirshfeld surfaces. Sun et al. (2003) describes the first synthesis and analysis of 1-alkyl-2-methyl pyrrolidinium ionic liquids involving the bis(trifluoromethanesulfonyl)imide anion.

Experimental top

The compound was synthesized following the procedure of Lancaster et al. (2002) for the analogous N-butyl-N-methyl pyrrolidinium chloride species: 1-methyl-1-propylpyrrolidinium chloride was synthesized by heating a solution of chloropropane (28 ml, 0.315 moles) and methyl pyrrolidine (20 ml, 0.287 moles) in 2-propanol at 323 K under nitrogen for 48 h. The resultant white solid was recrystallized from 2-propanol at 273 K. Crystals resulted after 2 days. Crystals were coated with Paratone N oil (Exxon Chemical Co., TX, USA) immediately after isolation and cooled in a stream of nitrogen vapour on the diffractometer. Melting point: 323.5 K.

Refinement top

All H atoms were initially located in a difference Fourier map. Thereafter, all H atoms were placed in geometrically fixed idealized positions and constrained to ride on their parent atoms with C—H distances in the range 0.95–1.00 Å and Uiso(H) = 1.2Ueq(C).

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: APEX2 (Bruker, 2005); data reduction: APEX2 (Bruker, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: POV-RAY (Persistence of Vision, 2003); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. Diagram of the unique component of (I) shown with 50% thermal ellipsoids and hydrogen atoms as spheres of arbitrary size.
[Figure 2] Fig. 2. Extended packing diagram of the unit-cell contents of (I) as viewed down the b axis.
1-Methyl-1-propylpyrrolidinium chloride top
Crystal data top
C8H18N+·Cl–Dx = 1.130 Mg m−3
Mr = 163.68Melting point: 323.5 K
Orthorhombic, PbcnMo Kα radiation
λ = 0.71073 Å
Hall symbol: -P 2n 2abCell parameters from 4825 reflections
a = 14.5863 (5) Åθ = 2.8–26.4º
b = 13.2196 (4) ŵ = 0.33 mm−1
c = 9.9779 (3) ÅT = 123 (2) K
V = 1923.99 (11) Å3Cubic, colourless
Z = 80.30 × 0.30 × 0.30 mm
F000 = 720
Data collection top
Bruker X8 APEX KappaCCD
diffractometer		1982 independent reflections
Radiation source: fine-focus sealed tube1800 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.030
T = 123(2) Kθmax = 26.4º
0.5° frames in φ and ω scansθmin = 2.1º
Absorption correction: multi-scan
(SADABS; Bruker, 2005)		h = −18→18
Tmin = 0.907, Tmax = 0.907k = −15→16
11550 measured reflectionsl = −11→12
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.031H-atom parameters constrained
wR(F2) = 0.079  w = 1/[σ2(Fo2) + (0.0361P)2 + 0.834P]
where P = (Fo2 + 2Fc2)/3
S = 1.04(Δ/σ)max = 0.001
1982 reflectionsΔρmax = 0.25 e Å−3
93 parametersΔρmin = −0.20 e Å−3
Primary atom site location: structure-invariant direct methodsExtinction correction: none
Crystal data top
C8H18N+·Cl–V = 1923.99 (11) Å3
Mr = 163.68Z = 8
Orthorhombic, PbcnMo Kα
a = 14.5863 (5) ŵ = 0.33 mm−1
b = 13.2196 (4) ÅT = 123 (2) K
c = 9.9779 (3) Å0.30 × 0.30 × 0.30 mm
Data collection top
Bruker X8 APEX KappaCCD
diffractometer		1982 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2005)		1800 reflections with I > 2σ(I)
Tmin = 0.907, Tmax = 0.907Rint = 0.030
11550 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.03193 parameters
wR(F2) = 0.079H-atom parameters constrained
S = 1.04Δρmax = 0.25 e Å−3
1982 reflectionsΔρmin = −0.20 e Å−3
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
Cl10.36024 (2)0.82436 (2)0.05218 (3)0.02423 (12)
N10.32912 (7)0.86923 (8)0.43497 (10)0.0179 (2)
C10.35707 (9)0.75928 (10)0.41992 (14)0.0241 (3)
H1A0.39390.74960.33760.029*
H1B0.30230.71520.41520.029*
C20.41390 (11)0.73488 (12)0.54424 (15)0.0323 (3)
H2A0.47930.72680.52020.039*
H2B0.39220.67140.58630.039*
C30.40131 (10)0.82444 (12)0.64053 (15)0.0309 (3)
H3A0.38840.80040.73260.037*
H3B0.45690.86740.64230.037*
C40.32014 (9)0.88251 (11)0.58455 (13)0.0242 (3)
H4A0.26160.85400.61740.029*
H4B0.32340.95490.60970.029*
C50.40372 (8)0.93610 (10)0.38042 (13)0.0209 (3)
H5A0.40450.93150.28240.031*
H5B0.46310.91410.41610.031*
H5C0.39221.00630.40720.031*
C60.23958 (8)0.88722 (10)0.36358 (13)0.0198 (3)
H6A0.19410.83740.39620.024*
H6B0.24870.87500.26660.024*
C70.20062 (9)0.99281 (11)0.38223 (14)0.0254 (3)
H7A0.19311.00730.47890.031*
H7B0.24331.04340.34420.031*
C80.10858 (10)0.99984 (12)0.31221 (18)0.0372 (4)
H8A0.11730.99260.21530.056*
H8B0.08061.06570.33130.056*
H8C0.06830.94580.34470.056*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl10.02343 (18)0.02619 (19)0.02308 (18)−0.00399 (13)−0.00151 (13)−0.00178 (12)
N10.0162 (5)0.0191 (5)0.0185 (5)−0.0015 (4)−0.0013 (4)0.0004 (4)
C10.0246 (7)0.0178 (6)0.0299 (7)0.0005 (5)−0.0008 (6)0.0012 (5)
C20.0282 (7)0.0287 (8)0.0401 (9)0.0006 (6)−0.0051 (6)0.0123 (6)
C30.0273 (7)0.0406 (9)0.0247 (7)−0.0068 (6)−0.0067 (6)0.0100 (6)
C40.0232 (6)0.0322 (8)0.0172 (6)−0.0044 (6)−0.0004 (5)−0.0005 (5)
C50.0163 (6)0.0223 (7)0.0241 (6)−0.0031 (5)0.0008 (5)0.0023 (5)
C60.0157 (6)0.0231 (6)0.0206 (6)−0.0019 (5)−0.0035 (5)−0.0014 (5)
C70.0208 (6)0.0257 (7)0.0298 (7)0.0018 (5)−0.0037 (6)−0.0049 (6)
C80.0258 (7)0.0314 (8)0.0543 (10)0.0050 (6)−0.0138 (7)−0.0065 (7)
Geometric parameters (Å, °) top
N1—C51.5038 (16)C4—H4B0.9900
N1—C61.5066 (16)C5—H5A0.9800
N1—C41.5085 (16)C5—H5B0.9800
N1—C11.5171 (17)C5—H5C0.9800
C1—C21.526 (2)C6—C71.5185 (18)
C1—H1A0.9900C6—H6A0.9900
C1—H1B0.9900C6—H6B0.9900
C2—C31.536 (2)C7—C81.5163 (19)
C2—H2A0.9900C7—H7A0.9900
C2—H2B0.9900C7—H7B0.9900
C3—C41.518 (2)C8—H8A0.9800
C3—H3A0.9900C8—H8B0.9800
C3—H3B0.9900C8—H8C0.9800
C4—H4A0.9900
C5—N1—C6111.31 (10)N1—C4—H4B111.0
C5—N1—C4110.64 (10)C3—C4—H4B111.0
C6—N1—C4111.98 (10)H4A—C4—H4B109.0
C5—N1—C1109.44 (10)N1—C5—H5A109.5
C6—N1—C1109.72 (10)N1—C5—H5B109.5
C4—N1—C1103.46 (10)H5A—C5—H5B109.5
N1—C1—C2105.54 (11)N1—C5—H5C109.5
N1—C1—H1A110.6H5A—C5—H5C109.5
C2—C1—H1A110.6H5B—C5—H5C109.5
N1—C1—H1B110.6N1—C6—C7114.30 (10)
C2—C1—H1B110.6N1—C6—H6A108.7
H1A—C1—H1B108.8C7—C6—H6A108.7
C1—C2—C3106.30 (12)N1—C6—H6B108.7
C1—C2—H2A110.5C7—C6—H6B108.7
C3—C2—H2A110.5H6A—C6—H6B107.6
C1—C2—H2B110.5C8—C7—C6109.34 (11)
C3—C2—H2B110.5C8—C7—H7A109.8
H2A—C2—H2B108.7C6—C7—H7A109.8
C4—C3—C2104.66 (11)C8—C7—H7B109.8
C4—C3—H3A110.8C6—C7—H7B109.8
C2—C3—H3A110.8H7A—C7—H7B108.3
C4—C3—H3B110.8C7—C8—H8A109.5
C2—C3—H3B110.8C7—C8—H8B109.5
H3A—C3—H3B108.9H8A—C8—H8B109.5
N1—C4—C3103.74 (11)C7—C8—H8C109.5
N1—C4—H4A111.0H8A—C8—H8C109.5
C3—C4—H4A111.0H8B—C8—H8C109.5
C5—N1—C1—C285.97 (12)C1—N1—C4—C340.98 (12)
C6—N1—C1—C2−151.63 (11)C2—C3—C4—N1−33.99 (14)
C4—N1—C1—C2−31.99 (13)C5—N1—C6—C7−63.82 (14)
N1—C1—C2—C310.96 (15)C4—N1—C6—C760.62 (14)
C1—C2—C3—C414.09 (15)C1—N1—C6—C7174.90 (11)
C5—N1—C4—C3−76.14 (13)N1—C6—C7—C8−177.02 (12)
C6—N1—C4—C3159.05 (10)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C1—H1B···Cl1i0.992.793.607 (1)141
C2—H2A···Cl1ii0.992.773.630 (2)146
C5—H5A···Cl10.982.773.648 (1)149
C5—H5C···Cl1iii0.982.713.656 (1)163
C6—H6A···Cl1i0.992.763.672 (1)153
C6—H6B···Cl10.992.773.666 (1)151
Symmetry codes: (i) −x+1/2, −y+3/2, z+1/2; (ii) −x+1, y, −z+1/2; (iii) x, −y+2, z+1/2.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C1—H1B···Cl1i0.992.793.607 (1)141
C2—H2A···Cl1ii0.992.773.630 (2)146
C5—H5A···Cl10.982.773.648 (1)149
C5—H5C···Cl1iii0.982.713.656 (1)163
C6—H6A···Cl1i0.992.763.672 (1)153
C6—H6B···Cl10.992.773.666 (1)151
Symmetry codes: (i) −x+1/2, −y+3/2, z+1/2; (ii) −x+1, y, −z+1/2; (iii) x, −y+2, z+1/2.
Acknowledgements top

The author [which one?] is grateful to Monash University for the Monash Graduate Scholarship and Monash International Postgraduate Research Scholarship, and to the Australian Research Council for a QEII fellowship for JMP.

references
References top

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