1-Ethyl-3-methyl-1H-imidazol-3-ium spiro­penta­borate

Parker, T.G.; Pubbi, D.; Beehler, A.; Albrecht-Schmitt, T.E.

doi:10.1107/S1600536813034363

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 70| Part 2| February 2014| Pages o171-o172

doi:10.1107/S1600536813034363

Open

access

1-Ethyl-3-methyl-1H-imidazol-3-ium spiropentaborate

T. Gannon Parker,^a Divya Pubbi,^a Austin Beehler ^a and Thomas E. Albrecht-Schmitt ^a ^*

^aDepartment of Chemistry and Biochemistry, Florida State University, 95 Chieftain Way, Tallahassee, Florida 32306, USA
^*Correspondence e-mail: albrecht-schmitt@chem.fsu.edu

(Received 17 October 2013; accepted 20 December 2013; online 18 January 2014)

In the anion of the title compound, (C₆H₁₁N₂)[B₅O₆(OH)₄], both six-membered borate rings adopt a flattened boat conformation with the spiro-B atom and its opposite O atom deviating from the remainders of the rings by 0.261 (3)/0.101 (2) and 0.160 (3)/0.109 (2) Å, respectively. The imidazolium cation also deviates from planarity due to rotation of the ethyl group (as indicated by the C—N—C—C torsion angle) by 71.4 (2)° out of the plane of the heterocycle. In the crystal, the anions are connected in a three-dimensional network through O—H⋯O hydrogen bonds, forming channels along the a-axis direction. The cations are situated in the channels, forming C—H⋯O hydrogen bonds with the anions.

CCDC reference: 978282

Related literature

Several compounds with the same anion as the title compound, in addition to several anions that bear some similarities to it, have been prepared previously with a number of different cations. For an extensive analysis of these oxoboron compounds, please refer to the review by Lin & Yang (2011 ). The ionic liquid 1-ethyl-3-methylimidazolium bromide, from which the cation of the title compound originates, is one of the most common and easily synthesized ionic liquids available. For an extensive review of ionic liquid chemistry, including details on the preparation of imidazolium-based ionic liquids, please refer to the text by Wasserscheid & Welton (2003 ).

Experimental

Crystal data

C₆H₁₁N₂⁺·B₅H₄O₁₀⁻
M_r = 329.25
Monoclinic, P 2₁ /c
a = 9.3599 (12) Å
b = 15.1128 (19) Å
c = 10.4770 (13) Å
β = 92.181 (2)°
V = 1480.9 (3) Å³
Z = 4
Mo Kα radiation
μ = 0.13 mm⁻¹
T = 100 K
0.3 × 0.2 × 0.1 mm

Data collection

Bruker D8 Quest diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1997 ) T_min = 0.970, T_max = 0.987
22780 measured reflections
3404 independent reflections
2902 reflections with I > 2σ(I)
R_int = 0.034

Refinement

R[F² > 2σ(F²)] = 0.033
wR(F²) = 0.088
S = 1.04
3404 reflections
226 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.27 e Å⁻³
Δρ_min = −0.22 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O7—H1⋯O9ⁱ	0.88 (2)	1.84 (2)	2.7169 (12)	172.8 (17)
O8—H2⋯O2ⁱⁱ	0.861 (18)	1.843 (18)	2.7022 (12)	174.9 (17)
O9—H3⋯O3ⁱⁱⁱ	0.87 (2)	1.80 (2)	2.6687 (11)	174.3 (18)
O10—H4⋯O4^iv	0.85 (2)	1.90 (2)	2.7426 (12)	173.9 (19)
C1—H1A⋯O5ⁱⁱⁱ	0.95	2.14	3.0265 (14)	155
C4—H4C⋯O10ⁱⁱ	0.98	2.47	3.4456 (16)	175
Symmetry codes: (i) x+1, y, z; (ii) $[x, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (iii) -x+2, -y, -z+1; (iv) $[x, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ .

Data collection: SMART (Bruker, 2000 ); cell refinement: SAINT; data reduction: SAINT and XPREP (Bruker, 1999 ); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXP97 (2008) and CrystalMaker (Kohn, 1995 ); software used to prepare material for publication: publCIF (Westrip, 2010 ).

Supporting information

CCDC reference: 978282

Crystal structure: contains datablock I. DOI: 10.1107/S1600536813034363/ld2114sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536813034363/ld2114Isup2.hkl

checkCIF report

Experimental top

The title compound formed as a byproduct in the ionothermal flux synthesis of a lanthanide borate cluster. 50.2 mg of erbium (III) oxide (Atomergic Chemetals Corp., 99.9 %), 97.2 mg of boric acid (EMD, 99.5 %) and 766 mg of 1-ethyl-3-methylimidazolium bromide were loaded into a PTFE-lined stainless steel autoclave with an internal volume of 23 mL in the presence of 100 mL of water for counterpressure. After heating for 3 days at 150 °C, the autoclave was cooled to 25 °C at a rate of 5 °C per hour. Colorless blocks of the title compound suitable for single crystal X-ray diffraction were isolated from the reaction.

Refinement top

Crystal data, data collection and structure refinement details are summarized in Table 1.

Results and discussion top

Related literature top

Several compounds with the same anion as the title compound, in addition to several anions that bear some similarities to it, have been prepared previously with a number of different cations. For an extensive analysis of these oxoboron compounds, please refer to the review by Lin & Yang (2011). The ionic liquid 1-ethyl-3-methylimidazolium bromide, from which the cation of the title compound originates, is one of the most common and easily synthesized ionic liquids available. For an extensive review of ionic liquid chemistry, including details on the preparation of imidazolium-based ionic liquids, please refer to the text by Wasserscheid & Welton (2003).

Structure description top

Several compounds with the same anion as the title compound, in addition to several anions that bear some similarities to it, have been prepared previously with a number of different cations. For an extensive analysis of these oxoboron compounds, please refer to the review by Lin & Yang (2011). The ionic liquid 1-ethyl-3-methylimidazolium bromide, from which the cation of the title compound originates, is one of the most common and easily synthesized ionic liquids available. For an extensive review of ionic liquid chemistry, including details on the preparation of imidazolium-based ionic liquids, please refer to the text by Wasserscheid & Welton (2003).

Computing details top

Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT and XPREP (Bruker, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXP97 (Sheldrick, 2008) and CrystalMaker (Kohn, 1995); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top

	Fig. 1. The molecular structure of 1-ethyl-3-methylimidazolium spiropentaborate including atomic numbering and 50% probability ellipsoids.
	Fig. 2. The view normal to the bc-plane showing the channels along which the cations reside. Hydrogen atoms not participating in hydrogen bonding have been omitted for clarity.

1-Ethyl-3-methyl-1H-imidazolium 4,8,10-tetrahydroxyspiro[5.5]pentaboroxan-6-uide top

Crystal data top

C₆H₁₁N₂⁺·B₅H₄O₁₀⁻	F(000) = 680
M_r = 329.25	D_x = 1.477 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 3404 reflections
a = 9.3599 (12) Å	θ = 2.2–27.5°
b = 15.1128 (19) Å	µ = 0.13 mm⁻¹
c = 10.4770 (13) Å	T = 100 K
β = 92.181 (2)°	Block, colorless
V = 1480.9 (3) Å³	0.3 × 0.2 × 0.1 mm
Z = 4

Data collection top

Bruker D8 Quest diffractometer	3404 independent reflections
Radiation source: Iµs microfocused	2902 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.034
0.5° wide ω exposures scans	θ_max = 27.5°, θ_min = 2.2°
Absorption correction: multi-scan (SADABS; Sheldrick, 1997)	h = −12→12
T_min = 0.970, T_max = 0.987	k = −19→19
22780 measured reflections	l = −13→13

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)] = 0.033	Hydrogen site location: difference Fourier map
wR(F²) = 0.088	H atoms treated by a mixture of independent and constrained refinement
S = 1.04	w = 1/[σ²(F_o²) + (0.0442P)² + 0.5004P] where P = (F_o² + 2F_c²)/3
3404 reflections	(Δ/σ)_max = 0.001
226 parameters	Δρ_max = 0.27 e Å⁻³
0 restraints	Δρ_min = −0.22 e Å⁻³

Crystal data top

C₆H₁₁N₂⁺·B₅H₄O₁₀⁻	V = 1480.9 (3) Å³
M_r = 329.25	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 9.3599 (12) Å	µ = 0.13 mm⁻¹
b = 15.1128 (19) Å	T = 100 K
c = 10.4770 (13) Å	0.3 × 0.2 × 0.1 mm
β = 92.181 (2)°

Data collection top

Bruker D8 Quest diffractometer	3404 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 1997)	2902 reflections with I > 2σ(I)
T_min = 0.970, T_max = 0.987	R_int = 0.034
22780 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.033	0 restraints
wR(F²) = 0.088	H atoms treated by a mixture of independent and constrained refinement
S = 1.04	Δρ_max = 0.27 e Å⁻³
3404 reflections	Δρ_min = −0.22 e Å⁻³
226 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
O1	0.92508 (8)	0.16731 (5)	0.69807 (7)	0.01589 (17)
O6	1.49330 (8)	0.16170 (5)	0.52890 (7)	0.01567 (17)
O3	1.08727 (8)	0.08183 (5)	0.57803 (7)	0.01407 (17)
O5	1.33102 (8)	0.07833 (5)	0.65159 (7)	0.01398 (17)
O2	1.17600 (8)	0.18727 (5)	0.73424 (7)	0.01490 (17)
O4	1.24439 (8)	0.19660 (5)	0.51455 (7)	0.01469 (17)
O9	0.83683 (8)	0.05749 (6)	0.56047 (8)	0.01843 (18)
O7	1.57125 (9)	0.03768 (5)	0.65252 (8)	0.01789 (18)
O8	1.40915 (9)	0.26406 (6)	0.37734 (8)	0.02090 (19)
O10	1.00812 (9)	0.25571 (6)	0.86757 (8)	0.01941 (19)
B1	0.95195 (13)	0.10211 (8)	0.60986 (11)	0.0140 (2)
B3	1.21157 (12)	0.13593 (8)	0.61957 (11)	0.0128 (2)
B2	1.03975 (13)	0.20424 (8)	0.76705 (12)	0.0146 (2)
B4	1.46484 (13)	0.09275 (8)	0.61107 (11)	0.0136 (2)
B5	1.37948 (13)	0.20780 (8)	0.47349 (12)	0.0146 (2)
N2	0.69980 (10)	0.11782 (7)	0.14371 (9)	0.0194 (2)
N1	0.70973 (12)	0.02735 (7)	−0.01465 (9)	0.0227 (2)
C2	0.73105 (14)	0.11083 (8)	−0.06212 (11)	0.0217 (3)
H2A	0.7474	0.1259	−0.1484	0.026*
C3	0.72443 (13)	0.16723 (8)	0.03697 (11)	0.0222 (3)
H3A	0.7349	0.2297	0.0336	0.027*
C5	0.7149 (2)	−0.05582 (9)	−0.08757 (13)	0.0378 (4)
H5A	0.6548	−0.0500	−0.1669	0.045*
H5B	0.6752	−0.1044	−0.0363	0.045*
C4	0.68454 (14)	0.15161 (9)	0.27388 (12)	0.0270 (3)
H4A	0.6555	0.1033	0.3296	0.041*
H4B	0.6117	0.1982	0.2730	0.041*
H4C	0.7762	0.1759	0.3059	0.041*
C1	0.69163 (14)	0.03353 (9)	0.11043 (11)	0.0240 (3)
H1A	0.6755	−0.0146	0.1664	0.029*
C6	0.8655 (3)	−0.07868 (12)	−0.12121 (18)	0.0576 (5)
H6A	0.9059	−0.0300	−0.1701	0.086*
H6B	0.8647	−0.1328	−0.1727	0.086*
H6C	0.9238	−0.0881	−0.0427	0.086*
H1	1.656 (2)	0.0489 (12)	0.6215 (16)	0.042 (5)*
H2	1.3336 (19)	0.2818 (11)	0.3353 (16)	0.034 (4)*
H3	0.864 (2)	0.0145 (13)	0.5119 (18)	0.047 (5)*
H4	1.081 (2)	0.2741 (13)	0.9101 (19)	0.049 (5)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0107 (4)	0.0196 (4)	0.0174 (4)	0.0003 (3)	0.0014 (3)	−0.0044 (3)
O6	0.0100 (4)	0.0192 (4)	0.0179 (4)	−0.0003 (3)	0.0018 (3)	0.0048 (3)
O3	0.0102 (4)	0.0169 (4)	0.0152 (4)	−0.0010 (3)	0.0019 (3)	−0.0035 (3)
O5	0.0107 (4)	0.0162 (4)	0.0152 (4)	0.0002 (3)	0.0019 (3)	0.0025 (3)
O2	0.0114 (4)	0.0191 (4)	0.0142 (4)	−0.0019 (3)	0.0014 (3)	−0.0035 (3)
O4	0.0113 (4)	0.0176 (4)	0.0153 (4)	0.0011 (3)	0.0016 (3)	0.0032 (3)
O9	0.0108 (4)	0.0223 (4)	0.0223 (4)	−0.0012 (3)	0.0028 (3)	−0.0094 (3)
O7	0.0114 (4)	0.0211 (4)	0.0213 (4)	0.0019 (3)	0.0028 (3)	0.0056 (3)
O8	0.0121 (4)	0.0272 (5)	0.0234 (4)	0.0007 (3)	0.0016 (3)	0.0115 (3)
O10	0.0124 (4)	0.0260 (4)	0.0199 (4)	−0.0009 (3)	0.0017 (3)	−0.0088 (3)
B1	0.0125 (5)	0.0162 (6)	0.0135 (5)	0.0004 (4)	0.0015 (4)	0.0005 (4)
B3	0.0106 (5)	0.0158 (6)	0.0121 (5)	−0.0008 (4)	0.0016 (4)	−0.0008 (4)
B2	0.0132 (6)	0.0156 (6)	0.0152 (6)	−0.0008 (4)	0.0011 (4)	0.0012 (4)
B4	0.0131 (5)	0.0154 (6)	0.0124 (5)	−0.0006 (4)	0.0011 (4)	−0.0008 (4)
B5	0.0132 (6)	0.0158 (6)	0.0148 (5)	−0.0007 (4)	0.0010 (4)	−0.0003 (4)
N2	0.0180 (5)	0.0238 (5)	0.0164 (5)	0.0005 (4)	0.0032 (4)	0.0010 (4)
N1	0.0336 (6)	0.0176 (5)	0.0170 (5)	−0.0006 (4)	0.0005 (4)	0.0030 (4)
C2	0.0284 (6)	0.0190 (6)	0.0181 (5)	0.0014 (5)	0.0042 (5)	0.0055 (4)
C3	0.0260 (6)	0.0193 (6)	0.0214 (6)	0.0011 (5)	0.0042 (5)	0.0037 (5)
C5	0.0731 (11)	0.0168 (6)	0.0230 (6)	−0.0010 (7)	−0.0052 (7)	0.0001 (5)
C4	0.0280 (7)	0.0351 (7)	0.0183 (6)	−0.0005 (5)	0.0064 (5)	−0.0040 (5)
C1	0.0309 (7)	0.0228 (6)	0.0184 (6)	−0.0039 (5)	0.0009 (5)	0.0048 (5)
C6	0.0941 (15)	0.0324 (9)	0.0470 (10)	0.0266 (9)	0.0111 (10)	−0.0080 (7)

Geometric parameters (Å, º) top

O1—B1	1.3805 (14)	N2—C1	1.3221 (17)
O1—B2	1.3881 (14)	N2—C3	1.3715 (15)
O6—B5	1.3822 (14)	N2—C4	1.4683 (15)
O6—B4	1.3839 (14)	N1—C1	1.3311 (15)
O3—B1	1.3571 (14)	N1—C2	1.3735 (15)
O3—B3	1.4740 (14)	N1—C5	1.4726 (16)
O5—B4	1.3553 (14)	C2—C3	1.3464 (17)
O5—B3	1.4463 (14)	C2—H2A	0.9500
O2—B2	1.3578 (14)	C3—H3A	0.9500
O2—B3	1.4788 (13)	C5—C6	1.506 (3)
O4—B5	1.3615 (14)	C5—H5A	0.9900
O4—B3	1.4736 (14)	C5—H5B	0.9900
O9—B1	1.3569 (14)	C4—H4A	0.9800
O9—H3	0.87 (2)	C4—H4B	0.9800
O7—B4	1.3566 (15)	C4—H4C	0.9800
O7—H1	0.88 (2)	C1—H1A	0.9500
O8—B5	1.3550 (15)	C6—H6A	0.9800
O8—H2	0.861 (18)	C6—H6B	0.9800
O10—B2	1.3512 (15)	C6—H6C	0.9800
O10—H4	0.85 (2)

B1—O1—B2	118.59 (9)	C1—N1—C2	108.53 (10)
B5—O6—B4	118.51 (9)	C1—N1—C5	125.35 (11)
B1—O3—B3	122.39 (9)	C2—N1—C5	126.02 (11)
B4—O5—B3	123.09 (9)	C3—C2—N1	106.90 (10)
B2—O2—B3	123.19 (9)	C3—C2—H2A	126.6
B5—O4—B3	122.40 (9)	N1—C2—H2A	126.6
B1—O9—H3	110.2 (12)	C2—C3—N2	107.35 (11)
B4—O7—H1	114.9 (12)	C2—C3—H3A	126.3
B5—O8—H2	112.8 (11)	N2—C3—H3A	126.3
B2—O10—H4	113.9 (13)	N1—C5—C6	111.52 (14)
O9—B1—O3	121.94 (10)	N1—C5—H5A	109.3
O9—B1—O1	116.60 (10)	C6—C5—H5A	109.3
O3—B1—O1	121.41 (10)	N1—C5—H5B	109.3
O5—B3—O4	111.49 (9)	C6—C5—H5B	109.3
O5—B3—O3	109.22 (9)	H5A—C5—H5B	108.0
O4—B3—O3	108.02 (8)	N2—C4—H4A	109.5
O5—B3—O2	108.86 (9)	N2—C4—H4B	109.5
O4—B3—O2	109.87 (9)	H4A—C4—H4B	109.5
O3—B3—O2	109.35 (8)	N2—C4—H4C	109.5
O10—B2—O2	122.81 (10)	H4A—C4—H4C	109.5
O10—B2—O1	116.70 (10)	H4B—C4—H4C	109.5
O2—B2—O1	120.49 (10)	N2—C1—N1	108.60 (10)
O5—B4—O7	118.49 (10)	N2—C1—H1A	125.7
O5—B4—O6	121.20 (10)	N1—C1—H1A	125.7
O7—B4—O6	120.31 (10)	C5—C6—H6A	109.5
O8—B5—O4	122.14 (10)	C5—C6—H6B	109.5
O8—B5—O6	116.87 (10)	H6A—C6—H6B	109.5
O4—B5—O6	120.99 (10)	C5—C6—H6C	109.5
C1—N2—C3	108.62 (10)	H6A—C6—H6C	109.5
C1—N2—C4	124.99 (11)	H6B—C6—H6C	109.5
C3—N2—C4	126.39 (11)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O7—H1···O9ⁱ	0.88 (2)	1.84 (2)	2.7169 (12)	172.8 (17)
O8—H2···O2ⁱⁱ	0.861 (18)	1.843 (18)	2.7022 (12)	174.9 (17)
O9—H3···O3ⁱⁱⁱ	0.87 (2)	1.80 (2)	2.6687 (11)	174.3 (18)
O10—H4···O4^iv	0.85 (2)	1.90 (2)	2.7426 (12)	173.9 (19)
C1—H1A···O5ⁱⁱⁱ	0.95	2.14	3.0265 (14)	155
C4—H4C···O10ⁱⁱ	0.98	2.47	3.4456 (16)	175

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O7—H1···O9ⁱ	0.88 (2)	1.84 (2)	2.7169 (12)	172.8 (17)
O8—H2···O2ⁱⁱ	0.861 (18)	1.843 (18)	2.7022 (12)	174.9 (17)
O9—H3···O3ⁱⁱⁱ	0.87 (2)	1.80 (2)	2.6687 (11)	174.3 (18)
O10—H4···O4^iv	0.85 (2)	1.90 (2)	2.7426 (12)	173.9 (19)
C1—H1A···O5ⁱⁱⁱ	0.95	2.14	3.0265 (14)	154.9
C4—H4C···O10ⁱⁱ	0.98	2.47	3.4456 (16)	174.7

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

Acknowledgements

We are grateful for support provided by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, Heavy Elements Program, US Department of Energy, under grant DE–FG02-13ER16414.

References

Bruker (1999). SAINT and XPREP. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Bruker (2000). SMART. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Kohn, S. (1995). Terra Nova, 7, 554–556. CrossRef Web of Science Google Scholar
Lin, Z.-E. & Yang, G.-Y. (2011). Eur. J. Inorg. Chem. 26, 3857–3867. Web of Science CrossRef Google Scholar
Sheldrick, G. M. (1997). SADABS. University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Wasserscheid, P. & Welton, T. (2003). In Ionic Liquids in Synthesis. Weinheim: VCH. Google Scholar
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925. Web of Science CrossRef CAS IUCr Journals Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 70| Part 2| February 2014| Pages o171-o172

doi:10.1107/S1600536813034363

Open

access