Crystal structure of 1-benzyl-3-methyl-1H-imidazolium hexa­fluorido­phosphate

Hillesheim, P.C.; Scipione, K.A.

doi:10.1107/S1600536814024301

organic compounds

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ISSN: 2056-9890

Volume 70| Part 12| December 2014| Pages o1248-o1249

doi:10.1107/S1600536814024301

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Crystal structure of 1-benzyl-3-methyl-1H-imidazolium hexafluoridophosphate

Patrick C. Hillesheim ^a ^* and Kent A. Scipione ^a

^aMississippi State University, Department of Chemistry, 1115 Hand Lab, Box 9573, Mississippi State, MS 39762, USA
^*Correspondence e-mail: pch110@msstate.edu

Edited by M. Zeller, Youngstown State University, USA (Received 25 October 2014; accepted 4 November 2014; online 12 November 2014)

In the title salt, C₁₁H₁₃N₂⁺·PF₆⁻, the dihedral angle between the planes of the imidazole and benzene rings is 84.72 (4)°. In the crystal, C—H⋯F interactions connect the cation and anion pairs into a three-dimensional network. Weak π–π interactions are observed between the imidazolium ring and the aromatic benzene ring of an adjacent molecule with C⋯C and C⋯N distances ranging from 3.3714 (16) to 3.4389 (15) Å.

Keywords: crystal structure; imidazolium; hexafluoridophosphate; hydrogen bonding; π–π interactions.

CCDC reference: 1032692

1. Related literature

For related structures containing imidazolium rings bearing N-benzyl groups, see: Haque et al. (2012 ); Jiang (2009 ); Lu et al. (2010 ); Pi et al. (2009 ). For an overview of applications for ionic liquids, see: Plechkova & Seddon (2008 ). For applications of benzyl-containing ionic liquids, see: Mahurin et al. (2011 ). For the synthesis of the title compound, see: Shkrob et al. (2013 ). For use of imidazolium compounds as carbene precursors, see: Scholl et al. (1999 ).

2. Experimental

2.1. Crystal data

C₁₁H₁₃N₂⁺·F₆P⁻
M_r = 318.20
Monoclinic, P 2₁ /c
a = 10.4989 (3) Å
b = 11.2755 (3) Å
c = 11.9769 (3) Å
β = 109.926 (1)°
V = 1332.95 (6) Å³
Z = 4
Mo Kα radiation
μ = 0.27 mm⁻¹
T = 100 K
0.45 × 0.27 × 0.12 mm

2.2. Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2014 ) T_min = 0.906, T_max = 0.991
42589 measured reflections
3188 independent reflections
2746 reflections with I > 2σ(I)
R_int = 0.055

2.3. Refinement

R[F² > 2σ(F²)] = 0.031
wR(F²) = 0.083
S = 1.07
3188 reflections
182 parameters
H-atom parameters constrained
Δρ_max = 0.27 e Å⁻³
Δρ_min = −0.42 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C1—H1⋯F3ⁱ	0.95	2.23	3.1503 (14)	164
C1—H1⋯F4ⁱ	0.95	2.61	3.2860 (14)	129
C3—H3⋯F5ⁱⁱ	0.95	2.30	3.1456 (15)	148
C9—H9⋯F2ⁱⁱⁱ	0.95	2.60	3.2680 (16)	128
Symmetry codes: (i) $[x, -y+{\script{3\over 2}}, z+{\script{1\over 2}}]$ ; (ii) -x+1, -y+1, -z+1; (iii) $[x-1, -y+{\script{3\over 2}}, z-{\script{1\over 2}}]$ .

Data collection: APEX2 (Bruker, 2014); cell refinement: SAINT (Bruker, 2013 ); data reduction: SAINT; program(s) used to solve structure: SHELXT (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009 ); software used to prepare material for publication: OLEX2.

Supporting information

CCDC reference: 1032692

Crystal structure: contains datablock I. DOI: 10.1107/S1600536814024301/zl2605sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536814024301/zl2605Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536814024301/zl2605Isup3.mol

checkCIF report

Structural commentary top

Ionic liquids are a class of materials which have found a wide range of applications in recent years (Plechkova & Seddon, 2008). In addition to their applications involving ionic liquids, imidazolium based salts are also commonly employed as starting materials for carbene ligands, perhaps most famously for their use in the so called Grubbs catalyst (Scholl et al., 1999). For both ionic liquids and carbene ligands, cationic nitrogen containing heterocycles are the dominant structural motif, providing an ideal combination of chemical and physical properties useful in both instances. Electronic and structural factors play a large role in the fine tuning of both ionic liquids and carbenes, thus the structure reported herein will provide a useful analysis of this common, yet unreported structure.

The asymmetric unit of the title compound contains one cation-anion pair (Fig. 1). The dihedral angle of the benzene ring and the imidazolium ring is 84.72° (4), see table 1. Crystal packing appears to be stabilized by the presence of several C—H···F interactions summarized in table 2 and shown in Figure 2. There are several close contacts between C7 and C8 of the benzene ring and the symmetry generated imidazole ring (symmetry operator 1-x,1/2+y,1.5-z) with C···C and C···N distances ranging from 3.3714 (16) to 3.4389 (15) (for C7···C2 and C8···N1 respectively). These interactions likely point towards the presence of a weak, highly slipped and tilted π-π interaction. No classical centroid-centroid π stacking was observed in the lattice.

Synthesis and crystallization top

The title compound was synthesized according to established literature procedures (Shkrob et al., 2013). Single crystals suitable for diffraction were grown by slow solvent evaporation from an ethanolic solution of the title compound.

Refinement top

Crystal data, data collection and structure refinement details are summarized in Table 1. H atoms were included at calculated positions using a riding model, with aromatic, methylene, and methyl C—H bond lengths of 0.95, 0.99 and 0.98Å, respectively. The U_iso(H) values were fixed at 1.5U_eq(C) for methyl H atoms, and 1.2U_eq(C) for all other C atoms.

Related literature top

For related structures containing imidazolium rings bearing N-benzyl groups, see: Haque et al. (2012); Jiang (2009); Lu et al. (2010); Pi et al. (2009). For an overview of applications for ionic liquids, see: Plechkova & Seddon (2008). For applications of benzyl-containing ionic liquids, see: Mahurin et al. (2011). For the synthesis of the title compound, see: Shkrob et al. (2013). For use of imidazolium compounds as carbene precursors, see: Scholl et al. (1999).

Computing details top

Data collection: APEX2 (Bruker, 2014); cell refinement: SAINT (Bruker, 2013); data reduction: SAINT (Bruker, 2013); program(s) used to solve structure: SHELXT (Sheldrick, 2008); program(s) used to refine structure: SHELXL (Sheldrick, 2008); molecular graphics: Olex2 (Dolomanov et al., 2009); software used to prepare material for publication: Olex2 (Dolomanov et al., 2009).

Figures top

Fig. 1. The molecular structure of the title compound with 50% probability ellipsoids. Nitrogen atoms shown in blue, carbon in grey, fluorine in pink, and phosphorous in green.

Fig. 2. Diagram of the hydrogen bonding observed in the title compound shown as pink dotted lines.

1-Benzyl-3-methyl-1H-imidazolium hexafluoridophosphate top

Crystal data top

C₁₁H₁₃N₂⁺·F₆P⁻	F(000) = 648
M_r = 318.20	D_x = 1.586 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
a = 10.4989 (3) Å	Cell parameters from 9735 reflections
b = 11.2755 (3) Å	θ = 2.6–27.9°
c = 11.9769 (3) Å	µ = 0.27 mm⁻¹
β = 109.926 (1)°	T = 100 K
V = 1332.95 (6) Å³	Plates, colourless
Z = 4	0.45 × 0.27 × 0.12 mm

Data collection top

Bruker APEXII CCD diffractometer	2746 reflections with I > 2σ(I)
Detector resolution: 8.33 pixels mm^-1	R_int = 0.055
combination of ω and ϕ–scans	θ_max = 27.9°, θ_min = 2.1°
Absorption correction: multi-scan (SADABS; Bruker, 2014)	h = −13→13
T_min = 0.906, T_max = 0.991	k = −14→14
42589 measured reflections	l = −15→15
3188 independent reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.031	H-atom parameters constrained
wR(F²) = 0.083	w = 1/[σ²(F_o²) + (0.0416P)² + 0.409P] where P = (F_o² + 2F_c²)/3
S = 1.07	(Δ/σ)_max = 0.001
3188 reflections	Δρ_max = 0.27 e Å⁻³
182 parameters	Δρ_min = −0.42 e Å⁻³
0 restraints

Crystal data top

C₁₁H₁₃N₂⁺·F₆P⁻	V = 1332.95 (6) Å³
M_r = 318.20	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 10.4989 (3) Å	µ = 0.27 mm⁻¹
b = 11.2755 (3) Å	T = 100 K
c = 11.9769 (3) Å	0.45 × 0.27 × 0.12 mm
β = 109.926 (1)°

Data collection top

Bruker APEXII CCD diffractometer	3188 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2014)	2746 reflections with I > 2σ(I)
T_min = 0.906, T_max = 0.991	R_int = 0.055
42589 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.031	0 restraints
wR(F²) = 0.083	H-atom parameters constrained
S = 1.07	Δρ_max = 0.27 e Å⁻³
3188 reflections	Δρ_min = −0.42 e Å⁻³
182 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
N1	0.71519 (10)	0.47646 (9)	0.73967 (9)	0.0195 (2)
N2	0.51532 (10)	0.53231 (9)	0.72989 (9)	0.0177 (2)
C1	0.64714 (12)	0.54719 (10)	0.78756 (10)	0.0188 (2)
H1	0.6860	0.5997	0.8523	0.023*
C2	0.62396 (13)	0.41476 (11)	0.64770 (11)	0.0219 (3)
H2	0.6453	0.3583	0.5979	0.026*
C3	0.49888 (13)	0.44926 (10)	0.64138 (11)	0.0210 (2)
H3	0.4154	0.4217	0.5866	0.025*
C4	0.86303 (13)	0.46510 (13)	0.77897 (13)	0.0296 (3)
H4A	0.8957	0.4942	0.7165	0.044*
H4B	0.8883	0.3816	0.7954	0.044*
H4C	0.9039	0.5119	0.8513	0.044*
C5	0.40534 (13)	0.59543 (11)	0.75594 (11)	0.0226 (3)
H5A	0.4451	0.6509	0.8229	0.027*
H5B	0.3491	0.5373	0.7803	0.027*
C6	0.31700 (12)	0.66383 (11)	0.64927 (11)	0.0190 (2)
C7	0.36887 (12)	0.76192 (10)	0.60829 (10)	0.0196 (2)
H7	0.4604	0.7850	0.6469	0.023*
C8	0.28734 (14)	0.82614 (11)	0.51126 (11)	0.0244 (3)
H8	0.3230	0.8933	0.4841	0.029*
C9	0.15414 (15)	0.79246 (13)	0.45415 (12)	0.0303 (3)
H9	0.0986	0.8364	0.3877	0.036*
C10	0.10175 (14)	0.69493 (14)	0.49367 (14)	0.0334 (3)
H10	0.0105	0.6716	0.4540	0.040*
C11	0.18284 (13)	0.63074 (12)	0.59182 (13)	0.0276 (3)
H11	0.1464	0.5644	0.6194	0.033*
P1	0.76866 (3)	0.81119 (3)	0.62758 (3)	0.01967 (10)
F1	0.71267 (8)	0.80793 (7)	0.73665 (7)	0.0306 (2)
F2	0.90222 (8)	0.74247 (7)	0.70492 (7)	0.0333 (2)
F3	0.82307 (9)	0.81640 (8)	0.51809 (7)	0.0363 (2)
F4	0.63354 (7)	0.88092 (7)	0.54915 (7)	0.02663 (18)
F5	0.69426 (10)	0.68792 (7)	0.58054 (8)	0.0392 (2)
F6	0.84023 (8)	0.93566 (7)	0.67485 (8)	0.0310 (2)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.0232 (5)	0.0161 (5)	0.0195 (5)	0.0017 (4)	0.0076 (4)	0.0036 (4)
N2	0.0232 (5)	0.0154 (4)	0.0148 (5)	0.0016 (4)	0.0069 (4)	0.0008 (4)
C1	0.0253 (6)	0.0146 (5)	0.0157 (5)	−0.0003 (4)	0.0061 (5)	0.0018 (4)
C2	0.0336 (7)	0.0163 (5)	0.0161 (6)	0.0028 (5)	0.0089 (5)	0.0001 (4)
C3	0.0293 (6)	0.0163 (5)	0.0155 (6)	−0.0010 (5)	0.0051 (5)	−0.0014 (4)
C4	0.0227 (6)	0.0292 (7)	0.0372 (8)	0.0041 (5)	0.0106 (6)	0.0070 (6)
C5	0.0271 (6)	0.0219 (6)	0.0224 (6)	0.0049 (5)	0.0132 (5)	0.0034 (5)
C6	0.0215 (6)	0.0171 (5)	0.0203 (6)	0.0023 (4)	0.0095 (5)	−0.0015 (4)
C7	0.0239 (6)	0.0183 (5)	0.0178 (6)	−0.0010 (5)	0.0088 (5)	−0.0033 (5)
C8	0.0387 (7)	0.0165 (6)	0.0200 (6)	0.0050 (5)	0.0127 (6)	−0.0005 (5)
C9	0.0345 (7)	0.0288 (7)	0.0235 (7)	0.0145 (6)	0.0043 (6)	−0.0007 (5)
C10	0.0206 (6)	0.0375 (8)	0.0368 (8)	0.0035 (5)	0.0030 (6)	−0.0075 (6)
C11	0.0236 (6)	0.0239 (6)	0.0364 (8)	−0.0024 (5)	0.0115 (6)	−0.0017 (6)
P1	0.02424 (17)	0.01596 (16)	0.01680 (17)	−0.00009 (11)	0.00438 (13)	0.00205 (11)
F1	0.0351 (4)	0.0369 (5)	0.0204 (4)	−0.0067 (3)	0.0103 (3)	0.0022 (3)
F2	0.0365 (5)	0.0288 (4)	0.0271 (4)	0.0110 (3)	0.0013 (3)	0.0054 (3)
F3	0.0406 (5)	0.0465 (5)	0.0264 (4)	0.0185 (4)	0.0175 (4)	0.0112 (4)
F4	0.0224 (4)	0.0296 (4)	0.0265 (4)	0.0025 (3)	0.0065 (3)	0.0077 (3)
F5	0.0572 (6)	0.0205 (4)	0.0282 (5)	−0.0093 (4)	−0.0007 (4)	−0.0038 (3)
F6	0.0262 (4)	0.0201 (4)	0.0450 (5)	−0.0052 (3)	0.0099 (4)	−0.0014 (3)

Geometric parameters (Å, º) top

N1—C1	1.3247 (16)	C6—C11	1.3914 (18)
N1—C2	1.3768 (16)	C7—H7	0.9500
N1—C4	1.4660 (16)	C7—C8	1.3891 (17)
N2—C1	1.3301 (16)	C8—H8	0.9500
N2—C3	1.3805 (15)	C8—C9	1.384 (2)
N2—C5	1.4774 (15)	C9—H9	0.9500
C1—H1	0.9500	C9—C10	1.383 (2)
C2—H2	0.9500	C10—H10	0.9500
C2—C3	1.3468 (18)	C10—C11	1.396 (2)
C3—H3	0.9500	C11—H11	0.9500
C4—H4A	0.9800	P1—F1	1.6053 (8)
C4—H4B	0.9800	P1—F2	1.5935 (8)
C4—H4C	0.9800	P1—F3	1.6000 (8)
C5—H5A	0.9900	P1—F4	1.6139 (8)
C5—H5B	0.9900	P1—F5	1.5999 (8)
C5—C6	1.5098 (17)	P1—F6	1.6016 (8)
C6—C7	1.3939 (17)

C1—N1—C2	108.65 (10)	C6—C7—H7	119.8
C1—N1—C4	125.58 (11)	C8—C7—C6	120.33 (12)
C2—N1—C4	125.77 (11)	C8—C7—H7	119.8
C1—N2—C3	108.67 (10)	C7—C8—H8	120.0
C1—N2—C5	125.40 (10)	C9—C8—C7	120.08 (12)
C3—N2—C5	125.93 (11)	C9—C8—H8	120.0
N1—C1—N2	108.57 (10)	C8—C9—H9	119.9
N1—C1—H1	125.7	C10—C9—C8	120.11 (13)
N2—C1—H1	125.7	C10—C9—H9	119.9
N1—C2—H2	126.3	C9—C10—H10	120.0
C3—C2—N1	107.35 (11)	C9—C10—C11	120.05 (13)
C3—C2—H2	126.3	C11—C10—H10	120.0
N2—C3—H3	126.6	C6—C11—C10	120.10 (13)
C2—C3—N2	106.76 (11)	C6—C11—H11	119.9
C2—C3—H3	126.6	C10—C11—H11	119.9
N1—C4—H4A	109.5	F1—P1—F4	89.53 (4)
N1—C4—H4B	109.5	F2—P1—F1	90.55 (5)
N1—C4—H4C	109.5	F2—P1—F3	90.29 (5)
H4A—C4—H4B	109.5	F2—P1—F4	179.90 (5)
H4A—C4—H4C	109.5	F2—P1—F5	90.55 (5)
H4B—C4—H4C	109.5	F2—P1—F6	90.39 (4)
N2—C5—H5A	109.3	F3—P1—F1	179.05 (5)
N2—C5—H5B	109.3	F3—P1—F4	89.63 (4)
N2—C5—C6	111.49 (10)	F3—P1—F6	90.11 (5)
H5A—C5—H5B	108.0	F5—P1—F1	89.80 (5)
C6—C5—H5A	109.3	F5—P1—F3	90.64 (5)
C6—C5—H5B	109.3	F5—P1—F4	89.51 (5)
C7—C6—C5	120.15 (11)	F5—P1—F6	178.80 (5)
C11—C6—C5	120.52 (11)	F6—P1—F1	89.44 (4)
C11—C6—C7	119.32 (12)	F6—P1—F4	89.56 (4)

N1—C2—C3—N2	0.15 (13)	C5—N2—C1—N1	−179.75 (10)
N2—C5—C6—C7	−67.85 (14)	C5—N2—C3—C2	179.52 (11)
N2—C5—C6—C11	112.96 (13)	C5—C6—C7—C8	−179.04 (11)
C1—N1—C2—C3	−0.35 (13)	C5—C6—C11—C10	179.65 (12)
C1—N2—C3—C2	0.11 (13)	C6—C7—C8—C9	−0.45 (18)
C1—N2—C5—C6	121.23 (12)	C7—C6—C11—C10	0.45 (19)
C2—N1—C1—N2	0.42 (13)	C7—C8—C9—C10	0.14 (19)
C3—N2—C1—N1	−0.33 (13)	C8—C9—C10—C11	0.5 (2)
C3—N2—C5—C6	−58.10 (15)	C9—C10—C11—C6	−0.8 (2)
C4—N1—C1—N2	−179.05 (11)	C11—C6—C7—C8	0.16 (18)
C4—N1—C2—C3	179.12 (11)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1···F3ⁱ	0.95	2.23	3.1503 (14)	164
C1—H1···F4ⁱ	0.95	2.61	3.2860 (14)	129
C3—H3···F5ⁱⁱ	0.95	2.30	3.1456 (15)	148
C9—H9···F2ⁱⁱⁱ	0.95	2.60	3.2680 (16)	128

Symmetry codes: (i) x, −y+3/2, z+1/2; (ii) −x+1, −y+1, −z+1; (iii) x−1, −y+3/2, z−1/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1···F3ⁱ	0.95	2.23	3.1503 (14)	163.6
C1—H1···F4ⁱ	0.95	2.61	3.2860 (14)	128.7
C3—H3···F5ⁱⁱ	0.95	2.30	3.1456 (15)	147.9
C9—H9···F2ⁱⁱⁱ	0.95	2.60	3.2680 (16)	127.7

Symmetry codes: (i) x, −y+3/2, z+1/2; (ii) −x+1, −y+1, −z+1; (iii) x−1, −y+3/2, z−1/2.

Acknowledgements

The authors wish to thank Mississippi State University and the Department of Chemistry for funding.

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ISSN: 2056-9890

Volume 70| Part 12| December 2014| Pages o1248-o1249

doi:10.1107/S1600536814024301

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