research communications
Crystal structures of 2,5-diazido-1,4-phenylene diacetate and 2,5-diazido-1,4-phenylene dibutyrate
aInstitute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9/163, A-1060 Vienna, Austria, and bInstitute for Chemical Technologies and Analytics, Division of Structural Chemistry, Vienna University of Technology, Getreidemarkt 9/164-SC, A-1060 Vienna, Austria
*Correspondence e-mail: mweil@mail.zserv.tuwien.ac.at
The asymmetric units of the title compounds, C10H8N6O4, (I), and C14H16N6O4, (II), each contain half of the respective molecule which is completed by inversion symmetry. The two molecules differ in the ester moiety (acetate versus butyrate) and the crystal symmetry is different, i.e. triclinic for (I) and monoclinic for (II). The diazidophenylene moieties are essentially planar [maximum deviation of 0.0216 (7) Å for (I) and 0.0330 (14) Å for (II)], and the ester functionalities are almost perpendicular to these planes, making dihedral angles of 79.93 (3)° for (I) and 79.42 (6)° for (II). In the crystals of both (I) and (II), there are no significant intermolecular interactions present.
Keywords: crystal structure; click chemistry; azides.
1. Chemical context
In recent years, copper(I)-catalysed cycloaddition of organic ). In materials chemistry, this kind of reaction is often applied for the synthesis of functional polymers (Qin et al., 2010).
and towards 1,4-disubstituted triazoles attained immense interest in various fields of organic chemistry and became famous as the `cream of the crop' of click chemistry (Moses & Moorhouse, 2007The title compounds, (I) and (II), were synthesized to investigate their applicability in such polymerizations, viz. AA–BB polymerizations with dialkynes. The synthetic accessibility of the two compounds from inexpensive starting materials is remarkable, making them suitable for large scale preparation. However, their electron-deficient character represents a challenge to the polymerization parameters. The crystal structures of (I) and (II) are reported herein.
2. Structural commentary
The molecular structures of (I) and (II) are displayed in Figs. 1 and 2, respectively. Both molecules possess inversion symmetry. Although the two molecules differ only in the ester moiety (acetate versus butyrate), the crystal symmetry is different, i.e. triclinic for (I), with Z = 1, and monoclinic for (II), with Z = 2. The diazidophenylene moieties do not differ significantly from planarity, with a maximum deviation of 0.0216 (7) Å in (I) and 0.0330 (14) Å in (II), for the unsubstituted atom C3 in both cases. The azide groups, both in trans positions to each other, deviate slightly from a linear arrangement, with an N—N—N angle of 173.01 (9)° for (I) and 172.59 (16)° for (II). The mean planes of the acetate [C—C(=O)—O)] and butyrate [C—C—C—C(=O)—O] groups are almost normal to the mean planes of the diazidophenylene moieties, with a dihedral angle of 79.93 (3)° for (I) and 79.42 (6)° for (II).
3. Supramolecular features
There are no notable features in terms of π–π stacking interactions or hydrogen bonding in either structure. The crystal packing of (I) and (II) seems to be dominated mainly by (Figs. 3 and 4, respectively).
4. Database survey
In the Cambridge Structural Database (Version 5.35, last update February 2014; Allen, 2002) no structures of compounds containing a trans-diazidophenylene entity are listed, making the two examples presented herein the only ones reported so far.
5. Synthesis and crystallization
Both target compounds were synthesized following a two-step protocol (Fig. 5), previously published for 2,5-diazido-1,4-phenylene diacetate by Moore et al. (1969). In view of the light sensitivity of the intermediate compound 2,5-diazidobenzene-1,4-diol, all reactions were carried out under light protection.
Preparation of 2,5-diazidobenzene-1,4-diol: 1,4-benzoquinone (10.81 g, 100.0 mmol, 1.0 equivalent) was dissolved in glacial acetic acid (100 ml, 1.0 M) and cooled to 288 K using an ice-water bath. NaN3 (14.3 g, 220 mol, 2.2 equivalents) was dissolved in water (44 ml, 5.0 M) and added to the cooled and stirred solution of 1,4-benzoquinone in one portion. Stirring was stopped after 15 min and the flask was sealed and stored at 278 K overnight for crystallization. Vacuum filtration afforded a light-yellow solid, which was washed three times with water and dried in vacuo overnight to afford 2,5-diazidobenzene-1,4-diol (yield: 6.60 g, 34.4 mmol, 69%). 1,4-Benzoquinone serves as starting material and as oxidation reagent in this reaction, resulting in a theoretical molar yield of only half of the applied starting material (50 mmol).
Preparation of 2,5-diazido-1,4-phenylene diacetate, (I): 2,5-diazidobenzene-1,4-diol (1.92 g, 10.0 mmol) was added to preheated (313 K) acetic anhydride (100 ml, 0.1 M) in one portion and the reaction stirred until complete dissolution of the starting material. The reaction mixture was then allowed to cool to room temperature and stored overnight to allow 2,5-diazido-1,4-phenylene diacetate to crystallize. Vacuum filtration afforded light-orange crystals of compound (I), which were washed with water three time (yield: 1.73 g, 6.26 mmol, 63%). 1H NMR (CDCl3, 200 MHz): δ 6.89 (s, 2H), 2.33 (s, 6H); 13C NMR (CDCl3, 50 MHz): δ 168.3 (s), 140.0 (s), 129.3 (s), 115.3 (d), 20.4 (q).
Preparation of 2,5-diazido-1,4-phenylene dibutyrate, (II): 2,5-diazidobenzene-1,4-diol (1.34 g, 7.0 mmol) was added to preheated (333 K) butyric anhydride (20 ml, 0.35 M) in one portion and the resulting suspension stirred for 45 min at this temperature. The reaction mixture was then allowed to cool to room temperature and stored for 5 days to allow 2,5-diazido-1,4-phenylene dibutyrate to crystallize. Vacuum filtration afforded yellow crystals of compound (II), which were washed with water three times and with ethanol twice (yield: 814 mg, 2.45 mmol, 35%). 1H NMR (CDCl3, 200 MHz): δ 6.88 (s, 2H), 2.57 (t, J = 7.4 Hz, 4H), 1.80 (sext, J = 7.4 Hz, 4H), 1.05 (t, J = 7.4 Hz, 6H); 13C NMR (CDCl3, 50 MHz): δ 171.1 (s), 140.0 (s), 129.3 (s), 115.3 (d), 35.6 (t), 18.3 (t), 13.6 (q).
6. Refinement
For both structures, (I) and (II), the H atoms were included in calculated positions and treated as riding atoms, with C—H = 0.96 Å and Uiso(H) = 1.2Ueq(C).
Supporting information
https://doi.org/10.1107/S1600536814013762/su0008sup1.cif
contains datablocks general, I, II. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536814013762/su0008Isup2.hkl
Structure factors: contains datablock II. DOI: https://doi.org/10.1107/S1600536814013762/su0008IIsup3.hkl
Supporting information file. DOI: https://doi.org/10.1107/S1600536814013762/su0008Isup4.cml
Supporting information file. DOI: https://doi.org/10.1107/S1600536814013762/su0008IIsup5.cml
For both compounds, data collection: APEX2 (Bruker, 2013); cell
SAINT-Plus (Bruker, 2013); data reduction: SAINT-Plus (Bruker, 2013); program(s) used to solve structure: SUPERFLIP (Palatinus & Chapuis, 2007); program(s) used to refine structure: JANA2006 (Petříček, et al., 2014); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: publCIF (Westrip, 2010).C10H8N6O4 | V = 295.86 (6) Å3 |
Mr = 276.2 | Z = 1 |
Triclinic, P1 | F(000) = 142 |
Hall symbol: -P 1 | Dx = 1.550 Mg m−3 |
a = 5.4293 (6) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 5.5678 (6) Å | θ = 3.8–32.8° |
c = 10.4945 (12) Å | µ = 0.12 mm−1 |
α = 101.508 (3)° | T = 100 K |
β = 104.544 (3)° | Irregular, light-orange |
γ = 97.057 (3)° | 0.65 × 0.55 × 0.25 mm |
Bruker Kappa APEXII CCD diffractometer | 2182 independent reflections |
Radiation source: X-ray tube | 1983 reflections with I > 3σ(I) |
Graphite monochromator | Rint = 0.037 |
ω and φ scans | θmax = 32.9°, θmin = 2.1° |
Absorption correction: multi-scan (SADABS; Bruker, 2013) | h = −8→8 |
Tmin = 0.92, Tmax = 0.97 | k = −8→8 |
15989 measured reflections | l = −15→16 |
Refinement on F | 16 constraints |
R[F > 3σ(F)] = 0.034 | H-atom parameters constrained |
wR(F) = 0.056 | Weighting scheme based on measured s.u.'s w = 1/(σ2(F) + 0.0001F2) |
S = 3.22 | (Δ/σ)max = 0.011 |
2182 reflections | Δρmax = 0.46 e Å−3 |
91 parameters | Δρmin = −0.23 e Å−3 |
0 restraints |
x | y | z | Uiso*/Ueq | ||
O1 | 0.25671 (10) | 0.01146 (10) | 0.20279 (5) | 0.01189 (16) | |
O2 | 0.59540 (11) | 0.28134 (10) | 0.35546 (6) | 0.01772 (18) | |
N1 | 0.36886 (13) | 0.27117 (12) | −0.19926 (6) | 0.0141 (2) | |
N2 | 0.19623 (12) | 0.39755 (11) | −0.19328 (6) | 0.01377 (19) | |
N3 | 0.04446 (14) | 0.51922 (13) | −0.19896 (8) | 0.0208 (2) | |
C1 | 0.42743 (13) | 0.13837 (12) | −0.09681 (7) | 0.0106 (2) | |
C2 | 0.38596 (13) | 0.01109 (13) | 0.10373 (7) | 0.01038 (19) | |
C3 | 0.31388 (13) | 0.14839 (12) | 0.00901 (7) | 0.0108 (2) | |
C4 | 0.38466 (14) | 0.15794 (13) | 0.33011 (7) | 0.0119 (2) | |
C5 | 0.22479 (16) | 0.13357 (15) | 0.42495 (7) | 0.0174 (2) | |
H1c3 | 0.185611 | 0.250721 | 0.016023 | 0.013* | |
H1c5 | 0.054271 | 0.162226 | 0.38606 | 0.0208* | |
H2c5 | 0.213484 | −0.031171 | 0.440361 | 0.0208* | |
H3c5 | 0.303627 | 0.253962 | 0.509525 | 0.0208* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0113 (3) | 0.0152 (2) | 0.0096 (2) | 0.00109 (19) | 0.00522 (18) | 0.00195 (18) |
O2 | 0.0164 (3) | 0.0197 (3) | 0.0148 (3) | −0.0021 (2) | 0.0057 (2) | 0.0004 (2) |
N1 | 0.0169 (3) | 0.0155 (3) | 0.0139 (3) | 0.0069 (2) | 0.0072 (2) | 0.0064 (2) |
N2 | 0.0161 (3) | 0.0132 (3) | 0.0137 (3) | 0.0024 (2) | 0.0056 (2) | 0.0056 (2) |
N3 | 0.0214 (4) | 0.0201 (3) | 0.0276 (4) | 0.0089 (3) | 0.0118 (3) | 0.0119 (3) |
C1 | 0.0113 (3) | 0.0107 (3) | 0.0096 (3) | 0.0016 (2) | 0.0032 (2) | 0.0021 (2) |
C2 | 0.0105 (3) | 0.0116 (3) | 0.0091 (3) | 0.0012 (2) | 0.0042 (2) | 0.0011 (2) |
C3 | 0.0106 (3) | 0.0115 (3) | 0.0107 (3) | 0.0027 (2) | 0.0040 (2) | 0.0018 (2) |
C4 | 0.0144 (3) | 0.0124 (3) | 0.0102 (3) | 0.0039 (2) | 0.0049 (2) | 0.0028 (2) |
C5 | 0.0186 (4) | 0.0228 (4) | 0.0129 (3) | 0.0030 (3) | 0.0091 (3) | 0.0037 (3) |
O1—C2 | 1.3924 (10) | C1—C3 | 1.3943 (11) |
O1—C4 | 1.3758 (8) | C2—C3 | 1.3810 (11) |
O2—C4 | 1.1971 (9) | C3—H1c3 | 0.96 |
N1—N2 | 1.2456 (10) | C4—C5 | 1.4904 (12) |
N1—C1 | 1.4167 (10) | C5—H1c5 | 0.96 |
N2—N3 | 1.1269 (10) | C5—H2c5 | 0.96 |
C1—C2i | 1.3944 (11) | C5—H3c5 | 0.96 |
C2—O1—C4 | 116.60 (5) | C2—C3—H1c3 | 120 |
N2—N1—C1 | 115.40 (7) | O1—C4—O2 | 122.32 (7) |
N1—N2—N3 | 173.01 (9) | O1—C4—C5 | 110.16 (6) |
N1—C1—C2i | 116.58 (7) | O2—C4—C5 | 127.51 (6) |
N1—C1—C3 | 124.83 (7) | C4—C5—H1c5 | 109.47 |
C2i—C1—C3 | 118.59 (7) | C4—C5—H2c5 | 109.47 |
O1—C2—C1i | 119.80 (7) | C4—C5—H3c5 | 109.47 |
O1—C2—C3 | 118.66 (7) | H1c5—C5—H2c5 | 109.47 |
C1i—C2—C3 | 121.42 (7) | H1c5—C5—H3c5 | 109.47 |
C1—C3—C2 | 120.00 (7) | H2c5—C5—H3c5 | 109.47 |
C1—C3—H1c3 | 120 |
Symmetry code: (i) −x+1, −y, −z. |
C14H16N6O4 | F(000) = 348 |
Mr = 332.3 | Dx = 1.361 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 7352 reflections |
a = 11.5875 (19) Å | θ = 2.7–27.0° |
b = 5.1485 (8) Å | µ = 0.10 mm−1 |
c = 14.327 (2) Å | T = 100 K |
β = 108.496 (5)° | Rod, light-yellow |
V = 810.6 (2) Å3 | 0.65 × 0.25 × 0.08 mm |
Z = 2 |
Bruker Kappa APEXII CCD diffractometer | 1781 independent reflections |
Radiation source: X-ray tube | 1211 reflections with I > 3σ(I) |
Graphite monochromator | Rint = 0.043 |
ω and φ scans | θmax = 28.1°, θmin = 2.0° |
Absorption correction: multi-scan (SADABS; Bruker, 2013) | h = −13→14 |
Tmin = 0.97, Tmax = 0.99 | k = −6→6 |
17268 measured reflections | l = −17→18 |
Refinement on F | 32 constraints |
R[F > 3σ(F)] = 0.042 | H-atom parameters constrained |
wR(F) = 0.048 | Weighting scheme based on measured s.u.'s w = 1/(σ2(F) + 0.0001F2) |
S = 2.15 | (Δ/σ)max = 0.005 |
1781 reflections | Δρmax = 0.26 e Å−3 |
109 parameters | Δρmin = −0.23 e Å−3 |
0 restraints |
x | y | z | Uiso*/Ueq | ||
O1 | 0.28390 (9) | 0.01294 (17) | 0.04347 (7) | 0.0217 (4) | |
O2 | 0.33949 (10) | −0.32997 (19) | 0.14715 (7) | 0.0269 (4) | |
N1 | 0.68785 (12) | 0.3626 (2) | 0.07891 (8) | 0.0224 (5) | |
N2 | 0.67449 (11) | 0.5255 (2) | 0.13953 (9) | 0.0225 (5) | |
N3 | 0.67447 (13) | 0.6825 (2) | 0.19484 (9) | 0.0296 (5) | |
C1 | 0.58925 (14) | 0.1863 (2) | 0.04072 (10) | 0.0177 (5) | |
C2 | 0.39470 (14) | 0.0013 (3) | 0.02402 (10) | 0.0181 (5) | |
C3 | 0.48219 (14) | 0.1877 (3) | 0.06446 (10) | 0.0190 (5) | |
C4 | 0.26254 (15) | −0.1781 (3) | 0.10334 (10) | 0.0214 (6) | |
C5 | 0.13432 (15) | −0.1622 (3) | 0.10373 (11) | 0.0265 (6) | |
C6 | 0.10348 (15) | −0.3423 (3) | 0.17548 (11) | 0.0303 (6) | |
C7 | −0.02989 (17) | −0.3320 (4) | 0.16734 (13) | 0.0411 (7) | |
H1c3 | 0.468982 | 0.31648 | 0.108459 | 0.0228* | |
H1c5 | 0.080047 | −0.194143 | 0.038568 | 0.0318* | |
H2c5 | 0.116086 | 0.013496 | 0.116656 | 0.0318* | |
H1c6 | 0.152049 | −0.298391 | 0.241353 | 0.0364* | |
H2c6 | 0.125093 | −0.51698 | 0.164467 | 0.0364* | |
H1c7 | −0.045158 | −0.450116 | 0.21394 | 0.0493* | |
H2c7 | −0.050726 | −0.158801 | 0.180958 | 0.0493* | |
H3c7 | −0.078376 | −0.380637 | 0.101973 | 0.0493* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0263 (7) | 0.0157 (5) | 0.0273 (6) | 0.0017 (5) | 0.0143 (5) | 0.0033 (4) |
O2 | 0.0324 (7) | 0.0217 (6) | 0.0303 (6) | 0.0055 (5) | 0.0150 (5) | 0.0053 (5) |
N1 | 0.0290 (9) | 0.0153 (6) | 0.0251 (7) | −0.0013 (6) | 0.0114 (6) | −0.0036 (6) |
N2 | 0.0264 (9) | 0.0159 (6) | 0.0247 (7) | −0.0015 (6) | 0.0072 (6) | 0.0037 (6) |
N3 | 0.0397 (10) | 0.0189 (7) | 0.0297 (7) | −0.0022 (6) | 0.0101 (7) | −0.0052 (6) |
C1 | 0.0231 (10) | 0.0108 (7) | 0.0194 (7) | −0.0002 (6) | 0.0069 (7) | 0.0020 (6) |
C2 | 0.0218 (10) | 0.0148 (7) | 0.0208 (8) | 0.0040 (7) | 0.0109 (7) | 0.0048 (6) |
C3 | 0.0283 (10) | 0.0112 (7) | 0.0189 (8) | 0.0023 (6) | 0.0095 (7) | 0.0016 (6) |
C4 | 0.0309 (11) | 0.0135 (7) | 0.0225 (8) | −0.0025 (7) | 0.0124 (7) | −0.0029 (6) |
C5 | 0.0286 (11) | 0.0212 (8) | 0.0320 (9) | 0.0005 (7) | 0.0131 (7) | 0.0019 (7) |
C6 | 0.0338 (11) | 0.0259 (9) | 0.0356 (9) | −0.0051 (8) | 0.0173 (8) | 0.0004 (7) |
C7 | 0.0376 (12) | 0.0516 (12) | 0.0386 (11) | −0.0118 (9) | 0.0184 (9) | 0.0030 (9) |
O1—C2 | 1.399 (2) | C4—C5 | 1.490 (3) |
O1—C4 | 1.3780 (19) | C5—C6 | 1.509 (2) |
O2—C4 | 1.2023 (17) | C5—H1c5 | 0.96 |
N1—N2 | 1.2518 (18) | C5—H2c5 | 0.96 |
N1—C1 | 1.4257 (18) | C6—C7 | 1.513 (3) |
N2—N3 | 1.1318 (18) | C6—H1c6 | 0.96 |
C1—C2i | 1.392 (2) | C6—H2c6 | 0.96 |
C1—C3 | 1.387 (2) | C7—H1c7 | 0.96 |
C2—C3 | 1.3825 (19) | C7—H2c7 | 0.96 |
C3—H1c3 | 0.96 | C7—H3c7 | 0.96 |
C2—O1—C4 | 116.81 (11) | C4—C5—H2c5 | 109.47 |
N2—N1—C1 | 115.62 (14) | C6—C5—H1c5 | 109.47 |
N1—N2—N3 | 172.59 (16) | C6—C5—H2c5 | 109.47 |
N1—C1—C2i | 115.94 (15) | H1c5—C5—H2c5 | 103.47 |
N1—C1—C3 | 124.96 (13) | C5—C6—C7 | 112.50 (13) |
C2i—C1—C3 | 119.09 (13) | C5—C6—H1c6 | 109.47 |
O1—C2—C1i | 119.18 (12) | C5—C6—H2c6 | 109.47 |
O1—C2—C3 | 118.96 (13) | C7—C6—H1c6 | 109.47 |
C1i—C2—C3 | 121.71 (15) | C7—C6—H2c6 | 109.47 |
C1—C3—C2 | 119.20 (14) | H1c6—C6—H2c6 | 106.26 |
C1—C3—H1c3 | 120.4 | C6—C7—H1c7 | 109.47 |
C2—C3—H1c3 | 120.4 | C6—C7—H2c7 | 109.47 |
O1—C4—O2 | 122.63 (16) | C6—C7—H3c7 | 109.47 |
O1—C4—C5 | 109.84 (12) | H1c7—C7—H2c7 | 109.47 |
O2—C4—C5 | 127.53 (15) | H1c7—C7—H3c7 | 109.47 |
C4—C5—C6 | 114.88 (12) | H2c7—C7—H3c7 | 109.47 |
C4—C5—H1c5 | 109.47 |
Symmetry code: (i) −x+1, −y, −z. |
Acknowledgements
The X-ray centre of the Vienna University of Technology is acknowledged for providing access to the single-crystal diffractometer.
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