organic compounds
(E)-4-(2,3-Dihydro-1,3-benzothiazol-2-ylidene)-3-methyl-1-phenyl-1H-pyrazol-5(4H)-one
aLaboratoire de Chimie Organique et Études Physicochimiques, ENS Rabat, Morocco, bLaboratoire de Chimie Organique Hétérocyclique, Université Mohammed V Rabat, Morocco, cInstitute of Nanomaterials and Nanotechnology, Avenue Armées Royals, Rabat, Morocco, and dInstitute of Chemistry, University of Osnabrück, Barbarastrasse 7, D-49069 Osnabrück, Germany
*Correspondence e-mail: hreuter@uos.de
In the title compound, C17H13N3OS, the dihedral angle between the ring systems is 2.22 (5)°. The N—H grouping participates in both intra- and intermolecular N—H⋯O hydrogen bonds, the latter leading to dimers related by a twofold rotation axis.
Related literature
For related structures, see: Teo et al. (1993); Chen (1994); Sawusch & Schilde (1999); Chu et al. (2003); Liu et al. (2004). For related literature, see: Harnden et al. (1978); Hatheway et al. (1978); Londershausen (1996); Tewari & Mishra (2001).
Experimental
Crystal data
|
Refinement
|
Data collection: APEX2 (Bruker, 2008); cell SAINT (Bruker, 2008); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).
Supporting information
https://doi.org/10.1107/S1600536810013176/fk2016sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810013176/fk2016Isup2.hkl
1.98 g (0.1 mol) (E)-3-methyl-4-(4-methyl-1-phenylpyrano[2,3-c]pyrazol-6(1H)-ylidene)-1-phenyl-1H-pyrazol-5(4H)-one, 2, were refluxed for 72 h with 2.136 ml (0.02 mol) 2-aminobenzenethiol, 1, in 50 ml n-butanol. On cooling the product forms transparent colourless crystals, which were filtered off in a yield of 50%. A suitable single crystal was selected under a polarization microsope and mounted on a 50 µm MicroMesh MiTeGen MicromountTM using FROMBLIN Y perfluoropolyether (LVAC 16/6, Aldrich).
Hydrogen atoms were clearly identified in difference Fourier syntheses, idealized and refined at calculated positions riding on the carbon atoms with C—H = 0.98 Å for methyl H atoms, 0.95 Å for aromatic H atoms and N—H = 0.88 Å. Methyl groups were allowed to rotate around the C—C–bond. Three common isotropic displacement parameters for the H–atoms of the three different subunits were refined.
The chemistry of pyrazole derivatives has been the subject of much interest due to their importance for various applications and their widespread potential and proven biological and pharmacological activities such as anti-inflammatory (Tewari et al., 2001), antimicrobial, antiviral (Harnden et al., 1978), anti-tumor (Hatheway et al., 1978), anti-fungal and pesticidal substances (Londershausen et al., 1996).
The new pyrazole derivative (E)-4-(benzo[d]thiazol-2-(3H)-ylidene)-3-methyl-1- phenyl-1H-pyrazol-5(4H)-one, 3, was synthesised according to reaction scheme 1. The solid state structure of 3 (Fig. 1) shows the typical structural features of its three subunits: a phenyl rest, a pyrazole derivative and a benzothiazole-like fragment.
In the pyrazol moiety the shortening of the bond between N12 and C13 [1.307 (2) Å] corresponds to a double bond in accordance with the formulation of the double bond in scheme 1.
All of the three subunits are for themselves planar, deviations from the least-square planes are small. Within the benzo[d]thiazole the greatest deviations result from the fact that the phenyl ring is planar whereas the remaining atoms of the thiazole ring are out of this plane with a maximum at C2 [-0.055 (2) Å]. Moreover, the complete molecule adopts are slightly curved conformation (Fig. 2). In the case of the 1,3-benzothiazole-pyrazole bond planarity should be result from the double bond [d(C—C) = 1.388 (2) Å] between the two subunits. Nevertheless, the interplanar dihedral angle between both ring systems is 2.22 (5)°. Between the pyrazole and the phenyl fragment the carbon-carbon single bond is shortened [d(C—C) = 1.416 (2) Å] but even longer than a double bond. In this case, the interplanar dihedral angle between both fragments is 7.16 (6)°. Similar values between these two subunits were obsereved earlier (Liu et al. 2004).
In the solid state, 3 forms dimers (Fig. 3) by bifurcated hydrogen bonds between the NH-group [N3] of the 1,3-benzothiazole-rest and O15 of a neighbouring molecule, both related by a twofold rotation axis. The second part of the bifurcated hydrogen bond system combines the NH-group with O15 within the same molecule.
For related structures, see: Teo et al. (1993); Chen (1994); Sawusch & Schilde (1999); Chu et al. (2003); Liu et al. (2004).
For related literature, see: Harnden et al. (1978); Hatheway et al. (1978); Londershausen (1996); Tewari & Mishra (2001).
Data collection: APEX2 (Bruker, 2008); cell
SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).C17H13N3OS | F(000) = 1280 |
Mr = 307.36 | Dx = 1.466 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2yc | Cell parameters from 9789 reflections |
a = 27.0144 (8) Å | θ = 2.9–30.6° |
b = 7.4021 (2) Å | µ = 0.24 mm−1 |
c = 14.0523 (4) Å | T = 100 K |
β = 97.466 (1)° | Prism, red |
V = 2786.12 (14) Å3 | 0.40 × 0.28 × 0.20 mm |
Z = 8 |
Bruker APEXII with a CCD detector diffractometer | 3359 independent reflections |
Radiation source: fine-focus sealed tube | 2928 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.041 |
φ and ω scans | θmax = 28.0°, θmin = 2.9° |
Absorption correction: multi-scan (SADABS; Bruker, 2008) | h = −35→35 |
Tmin = 0.875, Tmax = 0.956 | k = −9→9 |
57380 measured reflections | l = −18→18 |
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)] = 0.030 | Hydrogen site location: difference Fourier map |
wR(F2) = 0.082 | H-atom parameters constrained |
S = 1.05 | w = 1/[σ2(Fo2) + (0.0331P)2 + 3.8168P] where P = (Fo2 + 2Fc2)/3 |
3359 reflections | (Δ/σ)max = 0.001 |
203 parameters | Δρmax = 0.37 e Å−3 |
0 restraints | Δρmin = −0.26 e Å−3 |
C17H13N3OS | V = 2786.12 (14) Å3 |
Mr = 307.36 | Z = 8 |
Monoclinic, C2/c | Mo Kα radiation |
a = 27.0144 (8) Å | µ = 0.24 mm−1 |
b = 7.4021 (2) Å | T = 100 K |
c = 14.0523 (4) Å | 0.40 × 0.28 × 0.20 mm |
β = 97.466 (1)° |
Bruker APEXII with a CCD detector diffractometer | 3359 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2008) | 2928 reflections with I > 2σ(I) |
Tmin = 0.875, Tmax = 0.956 | Rint = 0.041 |
57380 measured reflections |
R[F2 > 2σ(F2)] = 0.030 | 0 restraints |
wR(F2) = 0.082 | H-atom parameters constrained |
S = 1.05 | Δρmax = 0.37 e Å−3 |
3359 reflections | Δρmin = −0.26 e Å−3 |
203 parameters |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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. |
x | y | z | Uiso*/Ueq | ||
S1 | 1.059848 (12) | 0.17433 (4) | 1.08323 (2) | 0.01678 (9) | |
C2 | 1.02064 (5) | 0.21310 (17) | 0.97688 (9) | 0.0151 (2) | |
N3 | 1.04276 (4) | 0.16259 (14) | 0.90040 (7) | 0.0160 (2) | |
H3 | 1.0281 | 0.1754 | 0.8411 | 0.0247 (19)* | |
C4 | 1.12040 (5) | 0.02162 (18) | 0.85676 (10) | 0.0198 (3) | |
H4 | 1.1098 | 0.0244 | 0.7896 | 0.0247 (19)* | |
C5 | 1.16636 (5) | −0.04948 (19) | 0.89339 (11) | 0.0235 (3) | |
H5 | 1.1876 | −0.0965 | 0.8506 | 0.0247 (19)* | |
C6 | 1.18205 (5) | −0.05341 (19) | 0.99209 (11) | 0.0250 (3) | |
H6 | 1.2138 | −0.1025 | 1.0152 | 0.0247 (19)* | |
C7 | 1.15201 (5) | 0.01318 (19) | 1.05696 (10) | 0.0222 (3) | |
H7 | 1.1626 | 0.0104 | 1.1241 | 0.0247 (19)* | |
C8 | 1.10583 (5) | 0.08405 (17) | 1.02029 (9) | 0.0174 (2) | |
C9 | 1.09021 (5) | 0.08893 (17) | 0.92167 (9) | 0.0167 (2) | |
N11 | 0.89806 (4) | 0.38442 (15) | 0.90615 (7) | 0.0151 (2) | |
N12 | 0.90079 (4) | 0.40940 (15) | 1.00569 (7) | 0.0167 (2) | |
C13 | 0.94462 (5) | 0.34924 (16) | 1.04238 (9) | 0.0157 (2) | |
C14 | 0.97279 (5) | 0.28461 (17) | 0.96994 (8) | 0.0150 (2) | |
C15 | 0.94124 (5) | 0.30754 (16) | 0.87995 (9) | 0.0147 (2) | |
O15 | 0.94948 (3) | 0.26778 (13) | 0.79710 (6) | 0.01790 (19) | |
C16 | 0.95996 (5) | 0.35330 (18) | 1.14808 (9) | 0.0194 (3) | |
H16A | 0.9322 | 0.3982 | 1.1800 | 0.030 (3)* | |
H16B | 0.9888 | 0.4333 | 1.1628 | 0.030 (3)* | |
H16C | 0.9689 | 0.2310 | 1.1710 | 0.030 (3)* | |
C21 | 0.85536 (5) | 0.45211 (17) | 0.84799 (9) | 0.0154 (2) | |
C22 | 0.81913 (5) | 0.54324 (19) | 0.89193 (9) | 0.0201 (3) | |
H22 | 0.8227 | 0.5545 | 0.9598 | 0.027 (2)* | |
C23 | 0.77785 (5) | 0.61730 (19) | 0.83640 (10) | 0.0219 (3) | |
H23 | 0.7534 | 0.6799 | 0.8666 | 0.027 (2)* | |
C24 | 0.77185 (5) | 0.60084 (19) | 0.73731 (10) | 0.0224 (3) | |
H24 | 0.7436 | 0.6522 | 0.6995 | 0.027 (2)* | |
C25 | 0.80761 (5) | 0.50843 (19) | 0.69414 (10) | 0.0225 (3) | |
H25 | 0.8035 | 0.4960 | 0.6263 | 0.027 (2)* | |
C26 | 0.84937 (5) | 0.43350 (18) | 0.74838 (9) | 0.0186 (3) | |
H26 | 0.8736 | 0.3703 | 0.7179 | 0.027 (2)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
S1 | 0.01820 (16) | 0.01755 (16) | 0.01406 (15) | 0.00014 (12) | 0.00009 (11) | 0.00048 (11) |
C2 | 0.0180 (6) | 0.0128 (5) | 0.0142 (5) | −0.0027 (4) | 0.0010 (4) | 0.0002 (4) |
N3 | 0.0175 (5) | 0.0166 (5) | 0.0138 (5) | 0.0006 (4) | 0.0019 (4) | 0.0002 (4) |
C4 | 0.0221 (6) | 0.0161 (6) | 0.0222 (6) | −0.0004 (5) | 0.0062 (5) | 0.0012 (5) |
C5 | 0.0213 (7) | 0.0184 (6) | 0.0322 (7) | 0.0009 (5) | 0.0090 (5) | 0.0006 (5) |
C6 | 0.0175 (6) | 0.0221 (7) | 0.0348 (8) | 0.0030 (5) | 0.0009 (5) | 0.0030 (6) |
C7 | 0.0211 (6) | 0.0196 (6) | 0.0248 (7) | −0.0003 (5) | −0.0013 (5) | 0.0025 (5) |
C8 | 0.0175 (6) | 0.0142 (6) | 0.0206 (6) | −0.0015 (5) | 0.0026 (5) | 0.0007 (5) |
C9 | 0.0168 (6) | 0.0133 (6) | 0.0200 (6) | −0.0014 (5) | 0.0024 (5) | 0.0019 (5) |
N11 | 0.0169 (5) | 0.0162 (5) | 0.0123 (5) | 0.0007 (4) | 0.0025 (4) | −0.0001 (4) |
N12 | 0.0204 (5) | 0.0177 (5) | 0.0122 (5) | 0.0000 (4) | 0.0026 (4) | −0.0010 (4) |
C13 | 0.0192 (6) | 0.0132 (6) | 0.0150 (6) | −0.0018 (5) | 0.0031 (5) | −0.0006 (4) |
C14 | 0.0177 (6) | 0.0138 (6) | 0.0135 (5) | −0.0016 (5) | 0.0016 (4) | −0.0003 (4) |
C15 | 0.0157 (6) | 0.0129 (5) | 0.0157 (6) | −0.0021 (4) | 0.0024 (4) | 0.0004 (4) |
O15 | 0.0188 (4) | 0.0220 (5) | 0.0132 (4) | 0.0011 (4) | 0.0034 (3) | −0.0014 (3) |
C16 | 0.0227 (6) | 0.0208 (6) | 0.0146 (6) | −0.0001 (5) | 0.0017 (5) | −0.0014 (5) |
C21 | 0.0153 (6) | 0.0131 (5) | 0.0176 (6) | −0.0027 (5) | 0.0015 (4) | 0.0014 (4) |
C22 | 0.0197 (6) | 0.0226 (7) | 0.0182 (6) | 0.0011 (5) | 0.0037 (5) | −0.0001 (5) |
C23 | 0.0175 (6) | 0.0212 (6) | 0.0275 (7) | 0.0011 (5) | 0.0050 (5) | 0.0003 (5) |
C24 | 0.0177 (6) | 0.0209 (7) | 0.0271 (7) | −0.0007 (5) | −0.0021 (5) | 0.0038 (5) |
C25 | 0.0238 (7) | 0.0245 (7) | 0.0183 (6) | −0.0010 (5) | −0.0008 (5) | 0.0009 (5) |
C26 | 0.0195 (6) | 0.0186 (6) | 0.0178 (6) | −0.0004 (5) | 0.0025 (5) | −0.0003 (5) |
S1—C2 | 1.7397 (13) | N12—C13 | 1.3067 (16) |
S1—C8 | 1.7485 (13) | C13—C14 | 1.4303 (17) |
C2—N3 | 1.3488 (16) | C13—C16 | 1.4896 (17) |
C2—C14 | 1.3883 (18) | C14—C15 | 1.4402 (16) |
N3—C9 | 1.3892 (16) | C15—O15 | 1.2486 (15) |
N3—H3 | 0.8800 | C16—H16A | 0.9800 |
C4—C5 | 1.3845 (19) | C16—H16B | 0.9800 |
C4—C9 | 1.3924 (18) | C16—H16C | 0.9800 |
C4—H4 | 0.9500 | C21—C26 | 1.3949 (17) |
C5—C6 | 1.397 (2) | C21—C22 | 1.3969 (18) |
C5—H5 | 0.9500 | C22—C23 | 1.3882 (19) |
C6—C7 | 1.387 (2) | C22—H22 | 0.9500 |
C6—H6 | 0.9500 | C23—C24 | 1.3861 (19) |
C7—C8 | 1.3892 (18) | C23—H23 | 0.9500 |
C7—H7 | 0.9500 | C24—C25 | 1.386 (2) |
C8—C9 | 1.3956 (17) | C24—H24 | 0.9500 |
N11—C15 | 1.3896 (16) | C25—C26 | 1.3921 (18) |
N11—N12 | 1.4034 (14) | C25—H25 | 0.9500 |
N11—C21 | 1.4158 (16) | C26—H26 | 0.9500 |
C2—S1—C8 | 91.25 (6) | C14—C13—C16 | 127.71 (12) |
N3—C2—C14 | 123.68 (11) | C2—C14—C13 | 130.85 (12) |
N3—C2—S1 | 110.81 (9) | C2—C14—C15 | 123.10 (11) |
C14—C2—S1 | 125.50 (10) | C13—C14—C15 | 106.05 (11) |
C2—N3—C9 | 115.43 (10) | O15—C15—N11 | 126.94 (11) |
C2—N3—H3 | 122.3 | O15—C15—C14 | 129.34 (12) |
C9—N3—H3 | 122.3 | N11—C15—C14 | 103.72 (10) |
C5—C4—C9 | 117.76 (12) | C13—C16—H16A | 109.5 |
C5—C4—H4 | 121.1 | C13—C16—H16B | 109.5 |
C9—C4—H4 | 121.1 | H16A—C16—H16B | 109.5 |
C4—C5—C6 | 121.25 (13) | C13—C16—H16C | 109.5 |
C4—C5—H5 | 119.4 | H16A—C16—H16C | 109.5 |
C6—C5—H5 | 119.4 | H16B—C16—H16C | 109.5 |
C7—C6—C5 | 121.13 (13) | C26—C21—C22 | 119.65 (12) |
C7—C6—H6 | 119.4 | C26—C21—N11 | 121.59 (11) |
C5—C6—H6 | 119.4 | C22—C21—N11 | 118.74 (11) |
C6—C7—C8 | 117.66 (13) | C23—C22—C21 | 120.00 (12) |
C6—C7—H7 | 121.2 | C23—C22—H22 | 120.0 |
C8—C7—H7 | 121.2 | C21—C22—H22 | 120.0 |
C7—C8—C9 | 121.27 (12) | C24—C23—C22 | 120.70 (13) |
C7—C8—S1 | 128.27 (11) | C24—C23—H23 | 119.7 |
C9—C8—S1 | 110.45 (10) | C22—C23—H23 | 119.7 |
N3—C9—C4 | 127.02 (12) | C23—C24—C25 | 119.07 (12) |
N3—C9—C8 | 112.04 (11) | C23—C24—H24 | 120.5 |
C4—C9—C8 | 120.93 (12) | C25—C24—H24 | 120.5 |
C15—N11—N12 | 112.38 (10) | C24—C25—C26 | 121.21 (12) |
C15—N11—C21 | 129.86 (10) | C24—C25—H25 | 119.4 |
N12—N11—C21 | 117.51 (10) | C26—C25—H25 | 119.4 |
C13—N12—N11 | 106.02 (10) | C25—C26—C21 | 119.36 (12) |
N12—C13—C14 | 111.83 (11) | C25—C26—H26 | 120.3 |
N12—C13—C16 | 120.47 (11) | C21—C26—H26 | 120.3 |
D—H···A | D—H | H···A | D···A | D—H···A |
N3—H3···O15 | 0.88 | 2.24 | 2.8483 (14) | 126 |
N3—H3···O15i | 0.88 | 2.22 | 2.9161 (13) | 136 |
Symmetry code: (i) −x+2, y, −z+3/2. |
Experimental details
Crystal data | |
Chemical formula | C17H13N3OS |
Mr | 307.36 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 100 |
a, b, c (Å) | 27.0144 (8), 7.4021 (2), 14.0523 (4) |
β (°) | 97.466 (1) |
V (Å3) | 2786.12 (14) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.24 |
Crystal size (mm) | 0.40 × 0.28 × 0.20 |
Data collection | |
Diffractometer | Bruker APEXII with a CCD detector |
Absorption correction | Multi-scan (SADABS; Bruker, 2008) |
Tmin, Tmax | 0.875, 0.956 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 57380, 3359, 2928 |
Rint | 0.041 |
(sin θ/λ)max (Å−1) | 0.661 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.030, 0.082, 1.05 |
No. of reflections | 3359 |
No. of parameters | 203 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.37, −0.26 |
Computer programs: APEX2 (Bruker, 2008), SAINT (Bruker, 2007), SAINT (Bruker, 2008), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 2006), SHELXTL (Sheldrick, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
N3—H3···O15 | 0.88 | 2.24 | 2.8483 (14) | 125.9 |
N3—H3···O15i | 0.88 | 2.22 | 2.9161 (13) | 136.4 |
Symmetry code: (i) −x+2, y, −z+3/2. |
Acknowledgements
We thank the Deutsche Forschungsgemeinschaft and the Government of Lower Saxony for their financial support in the acquisition of the diffractometer.
References
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The chemistry of pyrazole derivatives has been the subject of much interest due to their importance for various applications and their widespread potential and proven biological and pharmacological activities such as anti-inflammatory (Tewari et al., 2001), antimicrobial, antiviral (Harnden et al., 1978), anti-tumor (Hatheway et al., 1978), anti-fungal and pesticidal substances (Londershausen et al., 1996).
The new pyrazole derivative (E)-4-(benzo[d]thiazol-2-(3H)-ylidene)-3-methyl-1- phenyl-1H-pyrazol-5(4H)-one, 3, was synthesised according to reaction scheme 1. The solid state structure of 3 (Fig. 1) shows the typical structural features of its three subunits: a phenyl rest, a pyrazole derivative and a benzothiazole-like fragment.
In the pyrazol moiety the shortening of the bond between N12 and C13 [1.307 (2) Å] corresponds to a double bond in accordance with the formulation of the double bond in scheme 1.
All of the three subunits are for themselves planar, deviations from the least-square planes are small. Within the benzo[d]thiazole the greatest deviations result from the fact that the phenyl ring is planar whereas the remaining atoms of the thiazole ring are out of this plane with a maximum at C2 [-0.055 (2) Å]. Moreover, the complete molecule adopts are slightly curved conformation (Fig. 2). In the case of the 1,3-benzothiazole-pyrazole bond planarity should be result from the double bond [d(C—C) = 1.388 (2) Å] between the two subunits. Nevertheless, the interplanar dihedral angle between both ring systems is 2.22 (5)°. Between the pyrazole and the phenyl fragment the carbon-carbon single bond is shortened [d(C—C) = 1.416 (2) Å] but even longer than a double bond. In this case, the interplanar dihedral angle between both fragments is 7.16 (6)°. Similar values between these two subunits were obsereved earlier (Liu et al. 2004).
In the solid state, 3 forms dimers (Fig. 3) by bifurcated hydrogen bonds between the NH-group [N3] of the 1,3-benzothiazole-rest and O15 of a neighbouring molecule, both related by a twofold rotation axis. The second part of the bifurcated hydrogen bond system combines the NH-group with O15 within the same molecule.