electronic reprint Acta Crystallographica Section E Structure Reports Online ISSN 1600-5368 Editors: W. T. A. Harrison, H. Stoeckli-Evans, E. R. T. Tiekink and M. Weil Benzylammonium heptanoate Mary H. Wood and Stuart M. Clarke Acta Cryst. (2013). E69, o755–o756 This open-access article is distributed under the terms of the Creative Commons Attribution Licence http://creativecommons.org/licenses/by/2.0/uk/legalcode, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited. Acta Crystallographica Section E: Structure Reports Online is the IUCr’s highly popu- lar open-access structural journal. It provides a simple and easily accessible publication mechanism for the growing number of inorganic, metal-organic and organic crystal struc- ture determinations. The electronic submission, validation, refereeing and publication facilities of the journal ensure very rapid and high-quality publication, whilst key indica- tors and validation reports provide measures of structural reliability. The journal publishes over 4000 structures per year. The average publication time is less than one month. Crystallography Journals Online is available from journals.iucr.org Acta Cryst. (2013). E69, o755–o756 Wood and Clarke · C7H10N+·C7H13O2− Benzylammonium heptanoate Mary H. Wood and Stuart M. Clarke* BP Institute and Department of Chemistry, University of Cambridge, Cambridge, England Correspondence e-mail: stuart@bpi.cam.ac.uk Received 20 February 2013; accepted 8 April 2013 Key indicators: single-crystal X-ray study; T = 180 K; mean (C–C) = 0.002 A˚; R factor = 0.054; wR factor = 0.141; data-to-parameter ratio = 19.8. The title 1:1 stoichiometric salt, C7H10N + C7H13O2 , is formed by proton transfer between heptanoic acid and benzylamine. This combination contrasts to the recently published 2:1 acid– amine adduct of cation, anion and neutral acid molecule from the same components [Wood & Clarke (2013). Acta Cryst. E69, o346–o347]. There are N—H  O hydrogen bonds of moderate strength in the structure [the most important graph- set motifs are R24(8) and R 4 4(12)], as well as weak C—H  O interactions. Related literature For spectroscopic studies of acid–amine complexes, see: Kohler et al. (1981); Karlsson et al. (2000); Paivarinta et al. (2000); Smith et al. (2001, 2002). For recent diffraction studies of acid–amine complexes, see: Jefferson et al. (2011); Sun et al. (2011); Wood & Clarke (2012a,b, 2013). For the categorization of hydrogen bonds, see Gilli & Gilli (2009). For graph-set motifs, see Etter et al. (1990). Experimental Crystal data C7H10N + C7H13O2  Mr = 237.33 Triclinic, P1 a = 5.7379 (2) A˚ b = 7.7338 (3) A˚ c = 17.1670 (7) A˚  = 97.887 (2)  = 92.864 (2)  = 107.340 (2) V = 716.96 (5) A˚3 Z = 2 Mo K radiation  = 0.07 mm1 T = 180 K 0.46  0.07  0.05 mm Data collection Nonius KappaCCD diffractometer Absorption correction: multi-scan (SORTAV; Blessing, 1995) Tmin = 0.874, Tmax = 0.999 8415 measured reflections 3253 independent reflections 2308 reflections with I > 2(I) Rint = 0.043 Refinement R[F 2 > 2(F 2)] = 0.054 wR(F 2) = 0.141 S = 1.03 3253 reflections 164 parameters H atoms treated by a mixture of independent and constrained refinement max = 0.32 e A˚ 3 min = 0.19 e A˚ 3 Table 1 Hydrogen-bond geometry (A˚, ). D—H  A D—H H  A D  A D—H  A N1—H1A  O2 0.99 (2) 1.80 (2) 2.7802 (17) 168.7 (19) N1—H1B  O1i 0.98 (2) 1.73 (2) 2.6993 (17) 169 (2) N1—H1C  O2ii 1.00 (2) 1.87 (2) 2.8590 (18) 167 (2) C1—H1E  O1iii 0.99 2.40 3.280 (2) 148 C7—H7  O2 0.95 2.52 3.3528 (19) 146 Symmetry codes: (i) x þ 1; y; z; (ii) xþ 1;y;z; (iii) xþ 1;yþ 1;z. Data collection: COLLECT (Nonius, 1998); cell refinement: SCALEPACK (Otwinowski & Minor 1997); data reduction: DENZO (Otwinowski & Minor, 1997) and SCALEPACK; program(s) used to solve structure: SIR92 (Altomare et al. , 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL97. We thank the Department of Chemistry, the BP Institute and the Oppenheimer Trust for financial and technical assis- tance, and Dr J. E. Davies and Dr A. D. Bond for assistance in collecting and analysing the X-ray data. Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: FB2281). References Altomare, A., Cascarano, G., Giacovazzo, C. & Guagliardi, A. (1993). J. Appl. Cryst. 26, 343–350. Blessing, R. H. (1995). Acta Cryst. A51, 33–38. Etter, M. C., MacDonald, J. C. & Bernstein, J. (1990).Acta Cryst.B46, 256–262. Gilli, G. & Gilli, P. (2009). The Nature of the Hydrogen Bond. Outline of a Comprehensive Hydrogen Bond Theory. International Union of Crystal- lography. Oxford Science Publications. p. 61. New York, Oxford: Oxford University Press, Inc. Jefferson, A. E., Sun, C., Bond, A. D. & Clarke, S. M. (2011). Acta Cryst. E67, o655. Karlsson, S., Backlund, S. & Friman, R. (2000). Colloid Polym. Sci. 278, 8–14. Kohler, F., Atrops, H., Kalali, H., Liebermann, E., Wilhelm, E., Ratkovics, F. & Salamon, T. (1981). J. Phys. Chem. 85, 2520–2524. Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466–470. Nonius (1998). COLLECT. Nonius BV, Delft, The Netherlands. Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307–326. New York: Academic Press. Paivarinta, J., Karlsson, S., Hotokka, M. & Poso, A. (2000). Chem. Phys. Lett. 327, 420–424. Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. organic compounds Acta Cryst. (2013). E69, o755–o756 doi:10.1107/S1600536813009574 Wood and Clarke o755 Acta Crystallographica Section E Structure Reports Online ISSN 1600-5368 electronic reprint Smith, G., Wermuth, U. D., Bott, R. C., Healy, P. C. & White, J. M. (2002).Aust. J. Chem. 55, 349–356. Smith, G., Wermuth, U. D., Bott, R. C., White, J. M. & Willis, A. C. (2001). Aust. J. Chem. 54, 165–170. Sun, S., Bojdys, M. J., Clarke, S. M., Harper, L. D., Castro, M. A. & Medina, S. (2011). Langmuir, 27, 3626–3637. Wood, M. H. & Clarke, S. M. (2012a). Acta Cryst. E68, o3004. Wood, M. H. & Clarke, S. M. (2012b). Acta Cryst. E68, o3335. Wood, M. H. & Clarke, S. M. (2013). Acta Cryst. E69, o346–o347. organic compounds o756 Wood and Clarke  C7H10N+C7H13O2 Acta Cryst. (2013). E69, o755–o756 electronic reprint supplementary materials sup-1Acta Cryst. (2013). E69, o755–o756 supplementary materials Acta Cryst. (2013). E69, o755–o756 [doi:10.1107/S1600536813009574] Benzylammonium heptanoate Mary H. Wood and Stuart M. Clarke Comment There exist in the literature a number of examples of complexes formed between alkyl amines and carboxylic acids. These have been identified by a number of experimental methods, such as NMR and IR spectroscopy (e. g. Karlsson et al., 2000; Paivarinta et al. (2000); Smith et al. (2001, 2002)). Unfortunately, the atomic details of the materials and hence the nature of the bonding that can be obtained from single-crystal diffraction has only been determined in a few cases. This is partly due to the challenges in growing crystals large enough to be suitable for single-crystal diffraction. Some crystals of sufficient size have been grown (e. g. Jefferson et al. (2011); Wood & Clarke, 2012a, 2012b). Of the stoichiometic combinations reported to date, the majority have been 1:1 complexes, though some 2:1 and even 3:1 examples have been reported by calorimetry and NMR spectroscopy, generally when the environment is acid-rich (e. g. Kohler et al., 1981; Sun et al., 2011), and very recently using single-crystal diffraction (Wood & Clarke, 2013). Here we report growth of a suitable crystal for single-crystal X-ray diffraction of a 1:1 complex formed between heptanoic acid and benzylamine (Figs. 1 and 2). This work follows a previous publication (Wood & Clarke, 2013) in which an acid-rich 2:1 complex formed between these two species is described. In the previous work, one acid molecule donates its proton to the amine group and one acid group retains its proton. The hydrogen bonding extends across both the ions and the neutral acid molecule. As described below, the sample of the present study was grown by vapour phase condensation. Each preparation resulted in a batch of several crystals. The crystal used in this present study was taken from a different region of the same batch of samples as for the 2:1 combination (Wood & Clarke, 2013). We attribute the combination of compositions to the concentration gradients across the vapour streams in the preparation. In the crystal structure of the 1:1 complex (Figs. 1 and 2), each acid anion is involved in N-H···O hydrogen bonds of moderate strength (Gilli & Gilli, 2009) with three surrounding amine molecules (Table 1; Fig. 2), and vice versa each benzylammonium group donates its hydrogen to three different heptanoate molecules. The most important graph set motifs are R24(8) (Etter et al., 1990) - see Fig.3. (In this motif the donated atoms are H1a and H1c and the acceptors are the O2 atoms.) The other important motif is R44(12) with donated hydrogens H1b and H1c and accepting oxygens O1 and O2 (Fig. 3.). Moreover, there are also weak C-H···O interactions present in the structure (Table 1). Experimental Benzylamine and heptanoic acid (purities 99.7% and 99.8% respectively, determined by titration and gas chromatography) were purchased from Sigma Aldrich and used without further purification. A small volume of amine (approximately 1 ml) was placed into a small vial that was itself placed within a larger vial containing a similar volume of the acid, and left in an inert atmosphere. Extensive crystal growth was observed after a few weeks, particularly on a polypropylene surface included in the vial to encourage nucleation. electronic reprint supplementary materials sup-2Acta Cryst. (2013). E69, o755–o756 Refinement All the hydrogens were discernible in the difference electron density map. Nevertheless, the hydrogens attached to the C atoms were situated in the idealized positions and refined under these constraints: Caryl-Haryl=0.95, Cmethyl-Hmethyl=0.98, Cmethylene-Hmethylene=0.99 Å. Ueq(Haryl)=1.2Uiso(Caryl), Ueq(Hmethylene)=1.2Uiso(Cmethylene), Ueq(Hmethyl)=1.5Uiso(Cmethyl). The positional parameters of the hydrogens attached to N of the benzylammonium cation were freely refined while their Ueq(HN)=1.5Uiso(HN). Computing details Data collection: COLLECT (Nonius, 1998); cell refinement: SCALEPACK (Otwinowski & Minor 1997); data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR92 (Altomare et al. , 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008). Figure 1 Title molecules with atom labels. The displacement ellipsoids are drawn at the 50% probability level for non-H atoms. H atoms are shown as spheres of arbitrary size. electronic reprint supplementary materials sup-3Acta Cryst. (2013). E69, o755–o756 Figure 2 Hydrogen bonding around the ammonium cation. The symmetry codes: i: 1+x, y, z; ii: 1-x, -y, -z. electronic reprint supplementary materials sup-4Acta Cryst. (2013). E69, o755–o756 Figure 3 A section from the hydrogen bond pattern in the title structure. The symmetry codes: i: 1+x, y, z; ii: 1-x, -y, -z; iii: -x, -y, - z; iv: 2-x, -y, -z; v: -1+x, y, z. Benzylammonium heptanoate Crystal data C7H10N+·C7H13O2− Mr = 237.33 Triclinic, P1 Hall symbol: -P 1 a = 5.7379 (2) Å b = 7.7338 (3) Å c = 17.1670 (7) Å α = 97.887 (2)° β = 92.864 (2)° γ = 107.340 (2)° V = 716.96 (5) Å3 Z = 2 F(000) = 260 Dx = 1.099 Mg m−3 Mo Kα radiation, λ = 0.71073 Å Cell parameters from 9084 reflections θ = 1.0–27.5° µ = 0.07 mm−1 T = 180 K Needle, colourless 0.46 × 0.07 × 0.05 mm Data collection Nonius KappaCCD diffractometer Radiation source: fine-focus sealed tube Graphite monochromator ω and φ scans Absorption correction: multi-scan (SORTAV; Blessing, 1995) Tmin = 0.874, Tmax = 0.999 8415 measured reflections 3253 independent reflections 2308 reflections with I > 2σ(I) Rint = 0.043 θmax = 27.5°, θmin = 3.6° h = −7→7 k = −10→9 l = −22→22 electronic reprint supplementary materials sup-5Acta Cryst. (2013). E69, o755–o756 Refinement Refinement on F2 Least-squares matrix: full R[F2 > 2σ(F2)] = 0.054 wR(F2) = 0.141 S = 1.03 3253 reflections 164 parameters 0 restraints 82 constraints Primary atom site location: structure-invariant direct methods Secondary atom site location: difference Fourier map Hydrogen site location: difference Fourier map H atoms treated by a mixture of independent and constrained refinement w = 1/[σ2(Fo2) + (0.0544P)2 + 0.2301P] where P = (Fo2 + 2Fc2)/3 (Δ/σ)max < 0.001 Δρmax = 0.32 e Å−3 Δρmin = −0.19 e Å−3 Special details 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) x y z Uiso*/Ueq N1 0.7763 (2) 0.1651 (2) −0.04200 (8) 0.0352 (3) H1A 0.630 (4) 0.195 (3) −0.0239 (11) 0.053* H1B 0.919 (4) 0.247 (3) −0.0072 (12) 0.053* H1C 0.752 (4) 0.033 (3) −0.0380 (11) 0.053* C1 0.8129 (3) 0.1865 (2) −0.12452 (9) 0.0363 (4) H1D 0.9629 0.1556 −0.1381 0.044* H1E 0.8402 0.3168 −0.1298 0.044* C2 0.6010 (3) 0.06878 (19) −0.18296 (9) 0.0300 (3) C3 0.6366 (3) 0.0514 (2) −0.26288 (10) 0.0407 (4) H3 0.7927 0.1102 −0.2790 0.049* C4 0.4468 (4) −0.0507 (3) −0.31918 (10) 0.0478 (5) H4 0.4734 −0.0608 −0.3736 0.057* C5 0.2196 (3) −0.1378 (2) −0.29682 (10) 0.0448 (4) H5 0.0898 −0.2079 −0.3356 0.054* C6 0.1819 (3) −0.1225 (2) −0.21798 (10) 0.0379 (4) H6 0.0259 −0.1830 −0.2022 0.045* C7 0.3712 (3) −0.0191 (2) −0.16130 (9) 0.0327 (4) H7 0.3430 −0.0084 −0.1070 0.039* O1 0.1339 (2) 0.37947 (17) 0.06866 (7) 0.0499 (4) O2 0.35258 (19) 0.20902 (14) 0.01788 (6) 0.0345 (3) C8 0.3307 (3) 0.34204 (19) 0.06561 (8) 0.0274 (3) C9 0.5477 (3) 0.4606 (2) 0.12239 (8) 0.0297 (3) H9A 0.5971 0.5868 0.1097 0.036* H9B 0.6878 0.4119 0.1154 0.036* C10 0.4899 (3) 0.4671 (2) 0.20864 (8) 0.0305 (3) electronic reprint supplementary materials sup-6Acta Cryst. (2013). E69, o755–o756 H10A 0.3462 0.5117 0.2151 0.037* H10B 0.4458 0.3413 0.2217 0.037* C11 0.7043 (3) 0.5911 (2) 0.26616 (9) 0.0346 (4) H11A 0.8487 0.5476 0.2590 0.042* H11B 0.7467 0.7172 0.2535 0.042* C12 0.6502 (4) 0.5962 (2) 0.35193 (10) 0.0472 (5) H12A 0.6043 0.4697 0.3643 0.057* H12B 0.5081 0.6423 0.3594 0.057* C13 0.8663 (5) 0.7167 (3) 0.40931 (11) 0.0747 (7) H13A 1.0069 0.6686 0.4025 0.090* H13B 0.9147 0.8422 0.3958 0.090* C14 0.8143 (8) 0.7273 (5) 0.49474 (15) 0.1389 (17) H14A 0.9597 0.8085 0.5281 0.208* H14B 0.7732 0.6044 0.5094 0.208* H14C 0.6761 0.7758 0.5023 0.208* Atomic displacement parameters (Å2) U11 U22 U33 U12 U13 U23 N1 0.0267 (7) 0.0391 (8) 0.0357 (7) 0.0102 (6) −0.0036 (6) −0.0059 (6) C1 0.0289 (8) 0.0376 (8) 0.0371 (8) 0.0054 (7) 0.0018 (7) −0.0003 (7) C2 0.0310 (8) 0.0260 (7) 0.0320 (8) 0.0096 (6) 0.0007 (6) −0.0001 (6) C3 0.0426 (9) 0.0408 (9) 0.0362 (9) 0.0095 (8) 0.0054 (7) 0.0040 (7) C4 0.0623 (12) 0.0500 (10) 0.0280 (8) 0.0155 (9) −0.0009 (8) 0.0016 (7) C5 0.0487 (10) 0.0405 (9) 0.0379 (9) 0.0101 (8) −0.0157 (8) −0.0032 (7) C6 0.0330 (8) 0.0344 (8) 0.0428 (9) 0.0075 (7) −0.0044 (7) 0.0033 (7) C7 0.0307 (8) 0.0337 (8) 0.0314 (8) 0.0087 (6) −0.0008 (6) 0.0014 (6) O1 0.0302 (6) 0.0555 (8) 0.0574 (8) 0.0210 (6) −0.0126 (5) −0.0247 (6) O2 0.0326 (6) 0.0328 (6) 0.0359 (6) 0.0119 (5) 0.0001 (5) −0.0052 (5) C8 0.0275 (7) 0.0272 (7) 0.0264 (7) 0.0079 (6) 0.0011 (6) 0.0022 (6) C9 0.0250 (7) 0.0309 (8) 0.0305 (8) 0.0066 (6) 0.0003 (6) 0.0012 (6) C10 0.0293 (7) 0.0282 (7) 0.0309 (8) 0.0060 (6) −0.0010 (6) 0.0020 (6) C11 0.0363 (8) 0.0321 (8) 0.0306 (8) 0.0059 (7) −0.0044 (7) 0.0015 (6) C12 0.0616 (11) 0.0419 (10) 0.0307 (9) 0.0070 (9) −0.0012 (8) 0.0036 (7) C13 0.0991 (19) 0.0672 (14) 0.0341 (10) −0.0026 (13) −0.0178 (11) 0.0004 (10) C14 0.196 (4) 0.128 (3) 0.0330 (13) −0.031 (3) −0.0145 (17) −0.0003 (15) Geometric parameters (Å, º) N1—C1 1.467 (2) C8—C9 1.5148 (19) N1—H1A 0.99 (2) C9—C10 1.531 (2) N1—H1B 0.98 (2) C9—H9A 0.9900 N1—H1C 1.00 (2) C9—H9B 0.9900 C1—C2 1.510 (2) C10—C11 1.524 (2) C1—H1D 0.9900 C10—H10A 0.9900 C1—H1E 0.9900 C10—H10B 0.9900 C2—C7 1.386 (2) C11—C12 1.518 (2) C2—C3 1.391 (2) C11—H11A 0.9900 C3—C4 1.384 (2) C11—H11B 0.9900 C3—H3 0.9500 C12—C13 1.521 (3) electronic reprint supplementary materials sup-7Acta Cryst. (2013). E69, o755–o756 C4—C5 1.378 (3) C12—H12A 0.9900 C4—H4 0.9500 C12—H12B 0.9900 C5—C6 1.376 (2) C13—C14 1.507 (3) C5—H5 0.9500 C13—H13A 0.9900 C6—C7 1.389 (2) C13—H13B 0.9900 C6—H6 0.9500 C14—H14A 0.9800 C7—H7 0.9500 C14—H14B 0.9800 O1—C8 1.2486 (17) C14—H14C 0.9800 O2—C8 1.2653 (17) C1—N1—H1A 113.5 (11) C10—C9—H9A 109.1 C1—N1—H1B 109.7 (11) C8—C9—H9B 109.1 H1A—N1—H1B 107.3 (15) C10—C9—H9B 109.1 C1—N1—H1C 107.3 (11) H9A—C9—H9B 107.9 H1A—N1—H1C 107.5 (16) C11—C10—C9 112.75 (12) H1B—N1—H1C 111.6 (16) C11—C10—H10A 109.0 N1—C1—C2 114.05 (13) C9—C10—H10A 109.0 N1—C1—H1D 108.7 C11—C10—H10B 109.0 C2—C1—H1D 108.7 C9—C10—H10B 109.0 N1—C1—H1E 108.7 H10A—C10—H10B 107.8 C2—C1—H1E 108.7 C12—C11—C10 113.17 (14) H1D—C1—H1E 107.6 C12—C11—H11A 108.9 C7—C2—C3 118.30 (14) C10—C11—H11A 108.9 C7—C2—C1 123.43 (13) C12—C11—H11B 108.9 C3—C2—C1 118.25 (14) C10—C11—H11B 108.9 C4—C3—C2 120.71 (16) H11A—C11—H11B 107.8 C4—C3—H3 119.6 C11—C12—C13 113.06 (16) C2—C3—H3 119.6 C11—C12—H12A 109.0 C5—C4—C3 120.39 (16) C13—C12—H12A 109.0 C5—C4—H4 119.8 C11—C12—H12B 109.0 C3—C4—H4 119.8 C13—C12—H12B 109.0 C6—C5—C4 119.57 (15) H12A—C12—H12B 107.8 C6—C5—H5 120.2 C14—C13—C12 113.9 (2) C4—C5—H5 120.2 C14—C13—H13A 108.8 C5—C6—C7 120.24 (16) C12—C13—H13A 108.8 C5—C6—H6 119.9 C14—C13—H13B 108.8 C7—C6—H6 119.9 C12—C13—H13B 108.8 C2—C7—C6 120.78 (15) H13A—C13—H13B 107.7 C2—C7—H7 119.6 C13—C14—H14A 109.5 C6—C7—H7 119.6 C13—C14—H14B 109.5 O1—C8—O2 122.39 (13) H14A—C14—H14B 109.5 O1—C8—C9 117.80 (12) C13—C14—H14C 109.5 O2—C8—C9 119.80 (12) H14A—C14—H14C 109.5 C8—C9—C10 112.28 (12) H14B—C14—H14C 109.5 C8—C9—H9A 109.1 Hydrogen-bond geometry (Å, º) D—H···A D—H H···A D···A D—H···A N1—H1A···O2 0.99 (2) 1.80 (2) 2.7802 (17) 168.7 (19) electronic reprint supplementary materials sup-8Acta Cryst. (2013). E69, o755–o756 N1—H1B···O1i 0.98 (2) 1.73 (2) 2.6993 (17) 169 (2) N1—H1C···O2ii 1.00 (2) 1.87 (2) 2.8590 (18) 167 (2) C1—H1E···O1iii 0.99 2.40 3.280 (2) 148 C7—H7···O2 0.95 2.52 3.3528 (19) 146 Symmetry codes: (i) x+1, y, z; (ii) −x+1, −y, −z; (iii) −x+1, −y+1, −z. electronic reprint