organic compounds
1-Ethyl-4-isopropyl-1,2,4-triazolium bromide
aDepartment of Chemistry, Millersville University, Millersville, PA 17551, USA, and bDepartment of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
*Correspondence e-mail: edward.rajaseelan@millersville.edu
An ionic compound consisting of a triazolium cation and bromide anion, C7H14N3+·Br−, has been synthesized and structurally characterized using single-crystal X-ray diffraction and NMR. The compound crystallizes in the monoclinic P21/m with the non-hydrogen atoms of one cation lying on general positions and the others lying on a mirror plane. One bromide ion also lies on the mirror. The extended structure exhibits only weak intermolecular interactions between heterocyclic C—H groups and Br− ions.
Keywords: crystal structure; triazolium salt; heterocyclic ionic compound.
CCDC reference: 2293675
Structure description
Asymmetric 1,2,4-triazolium cations are of interest due to their utility as cations in ionic liquids (ILs) and as precursors to N-heterocyclic et al., 2014; Nelson, 2015; Strassner et al., 2013; Riederer et al., 2011; Chianese et al., 2004). The crystal structures of several triazolium salts have been reported (Peña Hueso et al., 2022; Kumasaki et al., 2021; Ponjan et al., 2020; Guino-o et al., 2015). We have synthesized many imidazolium and triazolium salts as precursors in the synthesis of NHC complexes of rhodium and iridium (Castaldi et al., 2021; Gnanamgari et al., 2007; Idrees et al., 2017; Nichol et al., 2011; Newman et al., 2021; Rushlow et al., 2022).
(NHCs) (DwivediThe molecular structure of the title compound is shown in Fig. 1. There are one and a half molecules in the with the non-hydrogen atoms of the N1 cation (except C4) and Br1 lying on the (x, 3/4, z) mirror plane. All the atoms of the N4 cation and Br2 occupy general positions. The bond lengths in the triazolium rings indicate aromaticity with C—N bonds exhibiting distances in the range of 1.305 (2)–1.366 (2) Å and N—N bond distances near 1.365 Å; the N—C—N bond angles in the triazolium ring range from 106.93 (18) to 111.35 (18)°. The C1—N2—C5—C6 torsion angle of the ethyl side chain in the N1 cation is constrained to be 0° by symmetry and the corresponding C8—N5—C12—C13 torsion angle in the N4 cation is 24.4 (2)°.
The crystal packing of the title compound is displayed in Fig. 2. There are weak non-classical hydrogen-bonding interactions between the heterocyclic C—H groupings and bromide ions. These weak interactions are shown as dotted red lines in Fig. 2 and summarized in Table 1.
Synthesis and crystallization
1-Ethyl triazole was purchased from AmBeed. All other compounds used in the syntheses of the title compound were obtained from Sigma-Aldrich. All materials in the synthesis were used as received. The synthesis was performed under nitrogen using reagent grade solvents, which were used as received without further purification. NMR spectra were recorded at room temperature in CDCl3 on a 400 MHz Varian spectrometer and referenced to the residual solvent peak (δ in p.p.m.).
1-Ethyl-1,2,4-triazole (2.01 g, 20.61 mmol) and isopropyl bromide (10.14 g, 82.4 mmol) were added to toluene (20 ml) and the mixture was refluxed for 48 h. Once cooled, the liquid was decanted, the white solid product that formed was washed with ether, filtered, and dried. The title compound crystallized as clear needles by slow diffusion of pentane into a CH2Cl2 solution. Yield: 1.04 g (23%). 1H NMR: CDCl3, δ (p.p.m.) 11.99 (s, 1 H, N—C5H—N), 8.85 (s, 1 H, N—C3H—N), 5.13 (m, 1 H, CH(CH3)2), 4.63 (q, 2 H, N—CH2), 1.74 (d, 6 H, CH(CH3)2), 1.65 (t, 3 H, CH2CH3). 13C NMR: δ (p.p.m.) 142.27 (N—CH—N), 141.84 (N—CH—N), 53.15 [CH(CH3)2], 48.36 (N—CH2), 23.14 [CH(CH3)2], 14.22 (N—CH2CH3).
Refinement
Crystal data, data collection, and structure .
details are summarized in Table 2Structural data
CCDC reference: 2293675
https://doi.org/10.1107/S2414314623007848/hb4448sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314623007848/hb4448Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2414314623007848/hb4448Isup3.cml
Data collection: CrysAlis PRO 1.171.42.79a (Rigaku OD, 2022); cell
CrysAlis PRO 1.171.42.79a (Rigaku OD, 2022); data reduction: CrysAlis PRO 1.171.42.79a (Rigaku OD, 2022); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018/3 (Sheldrick, 2015b); molecular graphics: Olex2 1.3 (Dolomanov et al., 2009); software used to prepare material for publication: publCIF (Westrip, 2010).C7H14N3+·Br− | F(000) = 672 |
Mr = 220.12 | Dx = 1.492 Mg m−3 |
Monoclinic, P21/m | Mo Kα radiation, λ = 0.71073 Å |
a = 8.1283 (2) Å | Cell parameters from 9609 reflections |
b = 21.3822 (7) Å | θ = 3.1–28.2° |
c = 8.6376 (2) Å | µ = 4.14 mm−1 |
β = 101.713 (3)° | T = 100 K |
V = 1469.96 (7) Å3 | Plate, colourless |
Z = 6 | 0.38 × 0.25 × 0.04 mm |
Rigaku XtaLAB Synergy-S diffractometer | 3747 independent reflections |
Radiation source: micro-focus sealed X-ray tube, PhotonJet (Mo) X-ray Source | 3142 reflections with I > 2σ(I) |
Mirror monochromator | Rint = 0.036 |
Detector resolution: 10.0000 pixels mm-1 | θmax = 28.3°, θmin = 2.6° |
ω scans | h = −10→10 |
Absorption correction: multi-scan (CrysAlis PRO; Rigaku OD; 2022) | k = −27→28 |
Tmin = 0.483, Tmax = 1.000 | l = −11→11 |
23168 measured reflections |
Refinement on F2 | Primary atom site location: dual |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.022 | H-atom parameters constrained |
wR(F2) = 0.052 | w = 1/[σ2(Fo2) + (0.0235P)2 + 0.254P] where P = (Fo2 + 2Fc2)/3 |
S = 1.04 | (Δ/σ)max = 0.001 |
3747 reflections | Δρmax = 0.38 e Å−3 |
168 parameters | Δρmin = −0.29 e Å−3 |
0 restraints |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Br1 | 0.65535 (3) | 0.750000 | 0.86475 (2) | 0.01997 (6) | |
Br2 | 0.36575 (2) | 0.58378 (2) | 1.16793 (2) | 0.01912 (5) | |
N1 | 0.5536 (2) | 0.750000 | 0.34816 (19) | 0.0180 (4) | |
N2 | 0.3012 (2) | 0.750000 | 0.22004 (19) | 0.0181 (4) | |
N3 | 0.2904 (2) | 0.750000 | 0.3756 (2) | 0.0225 (4) | |
C1 | 0.4576 (3) | 0.750000 | 0.2031 (2) | 0.0175 (4) | |
H1 | 0.495511 | 0.750000 | 0.106069 | 0.021* | |
C2 | 0.4471 (3) | 0.750000 | 0.4505 (2) | 0.0209 (4) | |
H2 | 0.482097 | 0.750000 | 0.562368 | 0.025* | |
C3 | 0.7407 (3) | 0.750000 | 0.3888 (3) | 0.0277 (5) | |
H3 | 0.777584 | 0.750000 | 0.506529 | 0.033* | |
C4 | 0.8056 (2) | 0.80896 (8) | 0.3239 (2) | 0.0324 (4) | |
H4A | 0.772489 | 0.809040 | 0.208337 | 0.049* | |
H4B | 0.928441 | 0.810248 | 0.355041 | 0.049* | |
H4C | 0.757925 | 0.845690 | 0.366538 | 0.049* | |
C5 | 0.1468 (3) | 0.750000 | 0.0987 (3) | 0.0315 (6) | |
H5A | 0.079611 | 0.787411 | 0.112921 | 0.038* | 0.5 |
H5B | 0.079611 | 0.712589 | 0.112921 | 0.038* | 0.5 |
C6 | 0.1791 (3) | 0.750000 | −0.0638 (3) | 0.0353 (6) | |
H6A | 0.225946 | 0.790528 | −0.085598 | 0.053* | 0.5 |
H6B | 0.073605 | 0.742719 | −0.139517 | 0.053* | 0.5 |
H6C | 0.259308 | 0.716754 | −0.073790 | 0.053* | 0.5 |
N4 | 0.45707 (16) | 0.58697 (5) | 0.70657 (14) | 0.0163 (3) | |
N5 | 0.71989 (15) | 0.59178 (5) | 0.80363 (14) | 0.0170 (3) | |
N6 | 0.70540 (17) | 0.59818 (6) | 0.64405 (15) | 0.0234 (3) | |
C7 | 0.5439 (2) | 0.59462 (7) | 0.58810 (18) | 0.0223 (3) | |
H7 | 0.493358 | 0.597046 | 0.478994 | 0.027* | |
C8 | 0.57173 (19) | 0.58536 (6) | 0.84100 (17) | 0.0167 (3) | |
H8 | 0.550409 | 0.580476 | 0.944460 | 0.020* | |
C9 | 0.27440 (18) | 0.57739 (7) | 0.69275 (18) | 0.0198 (3) | |
H9 | 0.249096 | 0.576878 | 0.801314 | 0.024* | |
C10 | 0.1780 (2) | 0.63095 (8) | 0.6001 (2) | 0.0296 (4) | |
H10A | 0.218468 | 0.670794 | 0.649669 | 0.044* | |
H10B | 0.057966 | 0.626396 | 0.599636 | 0.044* | |
H10C | 0.195525 | 0.630178 | 0.491108 | 0.044* | |
C11 | 0.2264 (2) | 0.51438 (8) | 0.61529 (19) | 0.0287 (4) | |
H11A | 0.240093 | 0.515644 | 0.505186 | 0.043* | |
H11B | 0.109054 | 0.505046 | 0.618208 | 0.043* | |
H11C | 0.299190 | 0.481809 | 0.672508 | 0.043* | |
C12 | 0.88457 (19) | 0.59542 (8) | 0.9095 (2) | 0.0242 (3) | |
H12A | 0.917169 | 0.639848 | 0.927513 | 0.029* | |
H12B | 0.969276 | 0.574799 | 0.859048 | 0.029* | |
C13 | 0.8832 (2) | 0.56445 (8) | 1.06588 (18) | 0.0246 (3) | |
H13A | 0.847326 | 0.520823 | 1.048013 | 0.037* | |
H13B | 0.804907 | 0.586585 | 1.119266 | 0.037* | |
H13C | 0.996325 | 0.565779 | 1.132088 | 0.037* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Br1 | 0.02633 (12) | 0.01928 (12) | 0.01483 (11) | 0.000 | 0.00543 (8) | 0.000 |
Br2 | 0.01946 (8) | 0.02267 (9) | 0.01542 (8) | −0.00045 (5) | 0.00400 (6) | −0.00014 (5) |
N1 | 0.0180 (9) | 0.0217 (9) | 0.0145 (8) | 0.000 | 0.0036 (7) | 0.000 |
N2 | 0.0193 (9) | 0.0205 (9) | 0.0149 (8) | 0.000 | 0.0043 (7) | 0.000 |
N3 | 0.0242 (10) | 0.0261 (10) | 0.0194 (9) | 0.000 | 0.0094 (7) | 0.000 |
C1 | 0.0181 (10) | 0.0194 (11) | 0.0142 (10) | 0.000 | 0.0015 (8) | 0.000 |
C2 | 0.0265 (11) | 0.0219 (11) | 0.0154 (10) | 0.000 | 0.0066 (9) | 0.000 |
C3 | 0.0196 (11) | 0.0469 (15) | 0.0148 (10) | 0.000 | −0.0009 (9) | 0.000 |
C4 | 0.0238 (8) | 0.0396 (10) | 0.0359 (9) | −0.0128 (7) | 0.0108 (7) | −0.0165 (8) |
C5 | 0.0159 (11) | 0.0541 (16) | 0.0222 (12) | 0.000 | −0.0021 (9) | 0.000 |
C6 | 0.0224 (12) | 0.0617 (18) | 0.0196 (11) | 0.000 | −0.0007 (9) | 0.000 |
N4 | 0.0165 (6) | 0.0197 (7) | 0.0132 (6) | 0.0001 (5) | 0.0040 (5) | 0.0014 (4) |
N5 | 0.0169 (6) | 0.0181 (7) | 0.0171 (6) | −0.0005 (5) | 0.0059 (5) | 0.0009 (4) |
N6 | 0.0244 (7) | 0.0275 (7) | 0.0204 (7) | −0.0008 (5) | 0.0093 (5) | −0.0004 (5) |
C7 | 0.0236 (8) | 0.0278 (9) | 0.0167 (7) | −0.0001 (6) | 0.0068 (6) | −0.0005 (6) |
C8 | 0.0170 (7) | 0.0164 (7) | 0.0170 (7) | 0.0000 (5) | 0.0041 (6) | 0.0013 (5) |
C9 | 0.0138 (7) | 0.0284 (9) | 0.0169 (7) | −0.0003 (6) | 0.0023 (6) | 0.0025 (6) |
C10 | 0.0242 (8) | 0.0386 (10) | 0.0273 (8) | 0.0118 (7) | 0.0077 (7) | 0.0102 (7) |
C11 | 0.0231 (8) | 0.0329 (9) | 0.0280 (8) | −0.0061 (7) | 0.0003 (7) | −0.0008 (7) |
C12 | 0.0134 (7) | 0.0286 (9) | 0.0302 (9) | −0.0012 (6) | 0.0035 (6) | 0.0032 (7) |
C13 | 0.0187 (8) | 0.0305 (9) | 0.0232 (8) | 0.0006 (6) | 0.0013 (6) | −0.0004 (6) |
N1—C1 | 1.335 (2) | N4—C7 | 1.366 (2) |
N1—C2 | 1.357 (3) | N4—C8 | 1.3337 (19) |
N1—C3 | 1.490 (3) | N4—C9 | 1.4795 (19) |
N2—N3 | 1.364 (2) | N5—N6 | 1.3662 (18) |
N2—C1 | 1.308 (3) | N5—C8 | 1.316 (2) |
N2—C5 | 1.463 (3) | N5—C12 | 1.4618 (19) |
N3—C2 | 1.307 (3) | N6—C7 | 1.305 (2) |
C3—C4 | 1.517 (2) | C9—C10 | 1.520 (2) |
C3—C4i | 1.517 (2) | C9—C11 | 1.520 (2) |
C5—C6 | 1.480 (3) | C12—C13 | 1.507 (2) |
C1—N1—C2 | 106.43 (18) | C7—N4—C9 | 128.25 (12) |
C1—N1—C3 | 126.56 (18) | C8—N4—C7 | 106.21 (13) |
C2—N1—C3 | 127.01 (17) | C8—N4—C9 | 125.39 (13) |
N3—N2—C5 | 119.20 (18) | N6—N5—C12 | 120.41 (13) |
C1—N2—N3 | 111.63 (16) | C8—N5—N6 | 111.24 (12) |
C1—N2—C5 | 129.18 (18) | C8—N5—C12 | 128.29 (13) |
C2—N3—N2 | 103.67 (18) | C7—N6—N5 | 104.00 (13) |
N2—C1—N1 | 106.93 (18) | N6—C7—N4 | 111.31 (13) |
N3—C2—N1 | 111.35 (18) | N5—C8—N4 | 107.24 (13) |
N1—C3—C4i | 109.14 (11) | N4—C9—C10 | 109.85 (12) |
N1—C3—C4 | 109.14 (11) | N4—C9—C11 | 108.78 (12) |
C4—C3—C4i | 112.4 (2) | C11—C9—C10 | 112.16 (13) |
N2—C5—C6 | 112.79 (19) | N5—C12—C13 | 111.39 (13) |
N2—N3—C2—N1 | 0.000 (1) | N5—N6—C7—N4 | 0.69 (16) |
N3—N2—C1—N1 | 0.000 (1) | N6—N5—C8—N4 | 0.42 (15) |
N3—N2—C5—C6 | 180.000 (1) | N6—N5—C12—C13 | −158.90 (13) |
C1—N1—C2—N3 | 0.000 (1) | C7—N4—C8—N5 | 0.01 (15) |
C1—N1—C3—C4i | −61.59 (13) | C7—N4—C9—C10 | −56.70 (19) |
C1—N1—C3—C4 | 61.59 (13) | C7—N4—C9—C11 | 66.41 (18) |
C1—N2—N3—C2 | 0.000 (1) | C8—N4—C7—N6 | −0.46 (16) |
C1—N2—C5—C6 | 0.000 (1) | C8—N4—C9—C10 | 128.34 (14) |
C2—N1—C1—N2 | 0.000 (1) | C8—N4—C9—C11 | −108.55 (15) |
C2—N1—C3—C4i | 118.41 (13) | C8—N5—N6—C7 | −0.69 (16) |
C2—N1—C3—C4 | −118.41 (13) | C8—N5—C12—C13 | 24.4 (2) |
C3—N1—C1—N2 | 180.000 (1) | C9—N4—C7—N6 | −176.18 (13) |
C3—N1—C2—N3 | 180.000 (1) | C9—N4—C8—N5 | 175.89 (12) |
C5—N2—N3—C2 | 180.000 (1) | C12—N5—N6—C7 | −177.94 (13) |
C5—N2—C1—N1 | 180.000 (1) | C12—N5—C8—N4 | 177.41 (13) |
Symmetry code: (i) x, −y+3/2, z. |
D—H···A | D—H | H···A | D···A | D—H···A |
C1—H1···Br1ii | 0.95 | 2.67 | 3.610 (2) | 170 |
C2—H2···Br2ii | 0.95 | 2.70 | 3.6344 (18) | 166 |
C7—H7···Br2ii | 0.95 | 2.69 | 3.6316 (15) | 170 |
C8—H8···Br2ii | 0.95 | 2.68 | 3.5635 (15) | 156 |
Symmetry code: (ii) x, y, z−1. |
Acknowledgements
AM was supported in this work by the Millersville University Murley Summer Undergraduate Research Fellowship.
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