1-Methyl-1-propyl­pyrrolidinium chloride

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

doi:10.1107/S1600536808005229

organic compounds

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Volume 64| Part 3| March 2008| Page o637

doi:10.1107/S1600536808005229

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1-Methyl-1-propylpyrrolidinium chloride

Pamela M. Dean,^a ^* Jennifer M. Pringle ^a and Douglas R. MacFarlane ^a

^aSchool of Chemistry, Monash University, Wellington Road, Clayton, Victoria 3800, Australia
^*Correspondence e-mail: pamela.dean@sci.monash.edu.au

(Received 15 February 2008; accepted 24 February 2008; online 29 February 2008)

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.

Related literature

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 ). For the first synthesis and analysis of the new pyrrolidinium family of molten salts, see: MacFarlane et al. (1999 ). For the quantitative comparison of intermolecular interactions using Hirshfeld surfaces, see: McKinnon et al. (2007 ). For the first synthesis and analysis of 1-alkyl-2-methyl pyrrolidinium ionic liquids involving the bis(trifluoromethanesulfonyl)imide anion, see: Sun et al. (2003 ).

Experimental

Crystal data

C₈H₁₈N⁺·Cl⁻
M_r = 163.68
Orthorhombic, P b c n
a = 14.5863 (5) Å
b = 13.2196 (4) Å
c = 9.9779 (3) Å
V = 1923.99 (11) Å³
Z = 8
Mo Kα radiation
μ = 0.33 mm⁻¹
T = 123 (2) K
0.30 × 0.30 × 0.30 mm

Data collection

Bruker Kappa APEXII diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ) T_min = 0.907, T_max = 0.907
11550 measured reflections
1982 independent reflections
1800 reflections with I > 2σ(I)
R_int = 0.030

Refinement

R[F² > 2σ(F²)] = 0.031
wR(F²) = 0.079
S = 1.04
1982 reflections
93 parameters
H-atom parameters constrained
Δρ_max = 0.25 e Å⁻³
Δρ_min = −0.20 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C1—H1B⋯Cl1ⁱ	0.99	2.79	3.607 (1)	141
C2—H2A⋯Cl1ⁱⁱ	0.99	2.77	3.630 (2)	146
C5—H5A⋯Cl1	0.98	2.77	3.648 (1)	149
C5—H5C⋯Cl1ⁱⁱⁱ	0.98	2.71	3.656 (1)	163
C6—H6A⋯Cl1ⁱ	0.99	2.76	3.672 (1)	153
C6—H6B⋯Cl1	0.99	2.77	3.666 (1)	151
Symmetry codes: (i) $[-x+{\script{1\over 2}}, -y+{\script{3\over 2}}, z+{\script{1\over 2}}]$ ; (ii) $[-x+1, y, -z+{\script{1\over 2}}]$ ; (iii) $[x, -y+2, z+{\script{1\over 2}}]$ .

Data collection: APEX2 (Bruker, 2005); cell refinement: APEX2; data reduction: APEX2; 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.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808005229/zl2101sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808005229/zl2101Isup2.hkl

checkCIF report

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.

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

	Fig. 1. Diagram of the unique component of (I) shown with 50% thermal ellipsoids and hydrogen atoms as spheres of arbitrary size.
	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⁻	D_x = 1.130 Mg m⁻³
M_r = 163.68	Melting point: 323.5 K
Orthorhombic, Pbcn	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2n 2ab	Cell parameters from 4825 reflections
a = 14.5863 (5) Å	θ = 2.8–26.4°
b = 13.2196 (4) Å	µ = 0.33 mm⁻¹
c = 9.9779 (3) Å	T = 123 K
V = 1923.99 (11) Å³	Cubic, colourless
Z = 8	0.30 × 0.30 × 0.30 mm
F(000) = 720

Data collection top

Bruker X8 APEX KappaCCD diffractometer	1982 independent reflections
Radiation source: fine-focus sealed tube	1800 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.030
0.5° frames in ϕ and ω scans	θ_max = 26.4°, θ_min = 2.1°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −18→18
T_min = 0.907, T_max = 0.907	k = −15→16
11550 measured reflections	l = −11→12

Refinement top

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)] = 0.031	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.079	H-atom parameters constrained
S = 1.04	w = 1/[σ²(F_o²) + (0.0361P)² + 0.834P] where P = (F_o² + 2F_c²)/3
1982 reflections	(Δ/σ)_max = 0.001
93 parameters	Δρ_max = 0.25 e Å⁻³
0 restraints	Δρ_min = −0.20 e Å⁻³

Crystal data top

C₈H₁₈N⁺·Cl⁻	V = 1923.99 (11) Å³
M_r = 163.68	Z = 8
Orthorhombic, Pbcn	Mo Kα radiation
a = 14.5863 (5) Å	µ = 0.33 mm⁻¹
b = 13.2196 (4) Å	T = 123 K
c = 9.9779 (3) Å	0.30 × 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)
T_min = 0.907, T_max = 0.907	R_int = 0.030
11550 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.031	0 restraints
wR(F²) = 0.079	H-atom parameters constrained
S = 1.04	Δρ_max = 0.25 e Å⁻³
1982 reflections	Δρ_min = −0.20 e Å⁻³
93 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

	x	y	z	U_iso*/U_eq
Cl1	0.36024 (2)	0.82436 (2)	0.05218 (3)	0.02423 (12)
N1	0.32912 (7)	0.86923 (8)	0.43497 (10)	0.0179 (2)
C1	0.35707 (9)	0.75928 (10)	0.41992 (14)	0.0241 (3)
H1A	0.3939	0.7496	0.3376	0.029*
H1B	0.3023	0.7152	0.4152	0.029*
C2	0.41390 (11)	0.73488 (12)	0.54424 (15)	0.0323 (3)
H2A	0.4793	0.7268	0.5202	0.039*
H2B	0.3922	0.6714	0.5863	0.039*
C3	0.40131 (10)	0.82444 (12)	0.64053 (15)	0.0309 (3)
H3A	0.3884	0.8004	0.7326	0.037*
H3B	0.4569	0.8674	0.6423	0.037*
C4	0.32014 (9)	0.88251 (11)	0.58455 (13)	0.0242 (3)
H4A	0.2616	0.8540	0.6174	0.029*
H4B	0.3234	0.9549	0.6097	0.029*
C5	0.40372 (8)	0.93610 (10)	0.38042 (13)	0.0209 (3)
H5A	0.4045	0.9315	0.2824	0.031*
H5B	0.4631	0.9141	0.4161	0.031*
H5C	0.3922	1.0063	0.4072	0.031*
C6	0.23958 (8)	0.88722 (10)	0.36358 (13)	0.0198 (3)
H6A	0.1941	0.8374	0.3962	0.024*
H6B	0.2487	0.8750	0.2666	0.024*
C7	0.20062 (9)	0.99281 (11)	0.38223 (14)	0.0254 (3)
H7A	0.1931	1.0073	0.4789	0.031*
H7B	0.2433	1.0434	0.3442	0.031*
C8	0.10858 (10)	0.99984 (12)	0.31221 (18)	0.0372 (4)
H8A	0.1173	0.9926	0.2153	0.056*
H8B	0.0806	1.0657	0.3313	0.056*
H8C	0.0683	0.9458	0.3447	0.056*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cl1	0.02343 (18)	0.02619 (19)	0.02308 (18)	−0.00399 (13)	−0.00151 (13)	−0.00178 (12)
N1	0.0162 (5)	0.0191 (5)	0.0185 (5)	−0.0015 (4)	−0.0013 (4)	0.0004 (4)
C1	0.0246 (7)	0.0178 (6)	0.0299 (7)	0.0005 (5)	−0.0008 (6)	0.0012 (5)
C2	0.0282 (7)	0.0287 (8)	0.0401 (9)	0.0006 (6)	−0.0051 (6)	0.0123 (6)
C3	0.0273 (7)	0.0406 (9)	0.0247 (7)	−0.0068 (6)	−0.0067 (6)	0.0100 (6)
C4	0.0232 (6)	0.0322 (8)	0.0172 (6)	−0.0044 (6)	−0.0004 (5)	−0.0005 (5)
C5	0.0163 (6)	0.0223 (7)	0.0241 (6)	−0.0031 (5)	0.0008 (5)	0.0023 (5)
C6	0.0157 (6)	0.0231 (6)	0.0206 (6)	−0.0019 (5)	−0.0035 (5)	−0.0014 (5)
C7	0.0208 (6)	0.0257 (7)	0.0298 (7)	0.0018 (5)	−0.0037 (6)	−0.0049 (6)
C8	0.0258 (7)	0.0314 (8)	0.0543 (10)	0.0050 (6)	−0.0138 (7)	−0.0065 (7)

Geometric parameters (Å, º) top

N1—C5	1.5038 (16)	C4—H4B	0.9900
N1—C6	1.5066 (16)	C5—H5A	0.9800
N1—C4	1.5085 (16)	C5—H5B	0.9800
N1—C1	1.5171 (17)	C5—H5C	0.9800
C1—C2	1.526 (2)	C6—C7	1.5185 (18)
C1—H1A	0.9900	C6—H6A	0.9900
C1—H1B	0.9900	C6—H6B	0.9900
C2—C3	1.536 (2)	C7—C8	1.5163 (19)
C2—H2A	0.9900	C7—H7A	0.9900
C2—H2B	0.9900	C7—H7B	0.9900
C3—C4	1.518 (2)	C8—H8A	0.9800
C3—H3A	0.9900	C8—H8B	0.9800
C3—H3B	0.9900	C8—H8C	0.9800
C4—H4A	0.9900

C5—N1—C6	111.31 (10)	N1—C4—H4B	111.0
C5—N1—C4	110.64 (10)	C3—C4—H4B	111.0
C6—N1—C4	111.98 (10)	H4A—C4—H4B	109.0
C5—N1—C1	109.44 (10)	N1—C5—H5A	109.5
C6—N1—C1	109.72 (10)	N1—C5—H5B	109.5
C4—N1—C1	103.46 (10)	H5A—C5—H5B	109.5
N1—C1—C2	105.54 (11)	N1—C5—H5C	109.5
N1—C1—H1A	110.6	H5A—C5—H5C	109.5
C2—C1—H1A	110.6	H5B—C5—H5C	109.5
N1—C1—H1B	110.6	N1—C6—C7	114.30 (10)
C2—C1—H1B	110.6	N1—C6—H6A	108.7
H1A—C1—H1B	108.8	C7—C6—H6A	108.7
C1—C2—C3	106.30 (12)	N1—C6—H6B	108.7
C1—C2—H2A	110.5	C7—C6—H6B	108.7
C3—C2—H2A	110.5	H6A—C6—H6B	107.6
C1—C2—H2B	110.5	C8—C7—C6	109.34 (11)
C3—C2—H2B	110.5	C8—C7—H7A	109.8
H2A—C2—H2B	108.7	C6—C7—H7A	109.8
C4—C3—C2	104.66 (11)	C8—C7—H7B	109.8
C4—C3—H3A	110.8	C6—C7—H7B	109.8
C2—C3—H3A	110.8	H7A—C7—H7B	108.3
C4—C3—H3B	110.8	C7—C8—H8A	109.5
C2—C3—H3B	110.8	C7—C8—H8B	109.5
H3A—C3—H3B	108.9	H8A—C8—H8B	109.5
N1—C4—C3	103.74 (11)	C7—C8—H8C	109.5
N1—C4—H4A	111.0	H8A—C8—H8C	109.5
C3—C4—H4A	111.0	H8B—C8—H8C	109.5

C5—N1—C1—C2	85.97 (12)	C1—N1—C4—C3	40.98 (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—C3	10.96 (15)	C4—N1—C6—C7	60.62 (14)
C1—C2—C3—C4	14.09 (15)	C1—N1—C6—C7	174.90 (11)
C5—N1—C4—C3	−76.14 (13)	N1—C6—C7—C8	−177.02 (12)
C6—N1—C4—C3	159.05 (10)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1B···Cl1ⁱ	0.99	2.79	3.607 (1)	141
C2—H2A···Cl1ⁱⁱ	0.99	2.77	3.630 (2)	146
C5—H5A···Cl1	0.98	2.77	3.648 (1)	149
C5—H5C···Cl1ⁱⁱⁱ	0.98	2.71	3.656 (1)	163
C6—H6A···Cl1ⁱ	0.99	2.76	3.672 (1)	153
C6—H6B···Cl1	0.99	2.77	3.666 (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.

Experimental details

Crystal data
Chemical formula	C₈H₁₈N⁺·Cl⁻
M_r	163.68
Crystal system, space group	Orthorhombic, Pbcn
Temperature (K)	123
a, b, c (Å)	14.5863 (5), 13.2196 (4), 9.9779 (3)
V (Å³)	1923.99 (11)
Z	8
Radiation type	Mo Kα
µ (mm⁻¹)	0.33
Crystal size (mm)	0.30 × 0.30 × 0.30

Data collection
Diffractometer	Bruker X8 APEX KappaCCD diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2005)
T_min, T_max	0.907, 0.907
No. of measured, independent and observed [I > 2σ(I)] reflections	11550, 1982, 1800
R_int	0.030
(sin θ/λ)_max (Å⁻¹)	0.626

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.031, 0.079, 1.04
No. of reflections	1982
No. of parameters	93
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.25, −0.20

Computer programs: APEX2 (Bruker, 2005), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), POV-RAY (Persistence of Vision, 2003).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1B···Cl1ⁱ	0.99	2.79	3.607 (1)	141
C2—H2A···Cl1ⁱⁱ	0.99	2.77	3.630 (2)	146
C5—H5A···Cl1	0.98	2.77	3.648 (1)	149
C5—H5C···Cl1ⁱⁱⁱ	0.98	2.71	3.656 (1)	163
C6—H6A···Cl1ⁱ	0.99	2.76	3.672 (1)	153
C6—H6B···Cl1	0.99	2.77	3.666 (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

PMD is grateful to Monash University for the Monash Graduate Scholarship and Monash International Postgraduate Research Scholarship. The Australian Research Council is thanked for a QEII fellowship for JMP.

References

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