organic compounds
3-(3-Nitrophenylaminocarbonyl)propionic acid: hydrogen-bonded sheets of alternating R22(8) and R66(36) rings
aInstituto de Química, Departamento de Química Inorgânica, Universidade Federal do Rio de Janeiro, 21945-970 Rio de Janeiro, RJ, Brazil, bDepartment of Chemistry, University of Aberdeen, Meston Walk, Old Aberdeen AB24 3UE, Scotland, and cSchool of Chemistry, University of St Andrews, Fife KY16 9ST, Scotland
*Correspondence e-mail: cg@st-andrews.ac.uk
Molecules of the title compound, C10H10N2O5, are linked by a combination of O—H⋯O and N—H⋯O hydrogen bonds into (100) sheets containing alternating R22(8) and R66(36) rings.
Comment
The reaction of C-substituted anilines, such as nitroanilines, with succinic anhydride yields initially 3-(arylaminocarbonyl)propionic acids, (A) (see scheme), dehydration of which yields the corresponding N-arylsuccinimides, (B). We have recently reported the molecular and supramolecular structures of the three isomeric N-(nitrophenyl)succinimides (B), where R = NO2 (Glidewell et al., 2005). We have now prepared all three isomeric 3-(nitrophenylaminocarbonyl)propionic acids (A), where R = NO2, but unfortunately only the 3-nitro isomer has provided crystals suitable for single-crystal We report here the molecular and supramolecular structures of 3-(3-nitrophenylaminocarbonyl)propionic acid, (I).
The molecules of (I) (Fig. 1) are linked into sheets by a combination of an N—H⋯O=C hydrogen bond, forming the usual amidic C(4) chain, and an O—H⋯O hydrogen bond, forming the usual centrosymmetric R22(8) (Bernstein et al., 1995) motif characteristic of simple (Table 1). Carboxyl atom O43 in the molecule at (x, y, z) acts as a hydrogen-bond donor to atom O44 in the molecule at (1 − x, 1 − y, 1 − z), so that the reference R22(8) dimer is centred at (, , ) (Fig. 2). Amide atoms N1 at (x, y, z) and (1 − x, 1 − y, 1 − z), which form part of the dimer centred at (, , ), act as hydrogen-bond donors to amide atoms O1 at (x, − y, − + z) and (1 − x, + y, − z), respectively, which themselves form parts of the R22(8) dimers centred at (, 0, 0) and (, 1, 1), respectively. Similarly, atoms O1 at (x, y, z) and (1 − x, 1 − y, 1 − z) accept hydrogen bonds from atoms N1 at (x, − y, + z) and (1 − x, + y, − z), which are pairs of the dimers centred, respectively, at (, 0, 1) and (, 1, 0). In this manner, each dimer
is directly linked to four other dimers via the amidic C(4) chains along [001], so forming a (100) sheet in which centrosymmetric R22(8) and R66(36) rings alternate in a chessboard fashion (Fig. 3).Experimental
A solution containing equimolar quantities of succinic anhydride and 3-nitroaniline (2 mmol of each) in 1,2-dichloroethane (20 ml) was heated under reflux for 1 h and then left overnight at room temperature. The solvent was removed under reduced pressure and the resulting solid product was recrystallized from ethanol (m.p. 455–457 K). IR (KBr): 3400–2000 (br), 1706, 1673, 1524, 1556, 1524, 1481, 1434, 1403, 1351, 1257, 1237, 1179, 1089, 1064, 993, 952, 891, 868,847, 819, 806, 737, 684, 670, 606, 540, 421, 498 cm−1.
Crystal data
|
Refinement
|
The P21/c was uniquely assigned from the All H atoms were located from difference maps and then treated as riding atoms, with C—H distances of 0.93 (aromatic) or 0.97 Å (CH2), an N—H distance of 0.89 Å, and an O—H distance of 0.82 Å, and with Uiso(H) = 1.2Ueq(C,N,O).
Data collection: SMART (Bruker, 2000); cell SAINT-Plus (Bruker, 2000); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 and PRPKAPPA (Ferguson, 1999).
Supporting information
10.1107/S0108270105040229/sk1893sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S0108270105040229/sk1893Isup2.hkl
A solution containing equimolar quantities of succinic anhydride and 3-nitroaniline (2 mmol of each) in 1,2-dichloroethane (20 ml) was heated under reflux for 1 h and then left overnight at room temperature. The solvent was removed under reduced presure and the resulting solid product was recrystallized from ethanol (m.p. 455–457 K). IR (KBr): 3400–2000 (br), 1706, 1673, 1524, 1556, 1524, 1481, 1434, 1403, 1351, 1257, 1237, 1179, 1089, 1064, 993, 952, 891, 868,847, 819, 806, 737, 684, 670, 606, 540, 421, 498 cm-1.
The
P21/c was uniquely assigned from the All H atoms were located from difference maps, and then treated as riding atoms, with distances C—H 0.93 Å (aromatic) or 0.97 Å (CH2), N—H 0.89 Å, and O—H 0.82 Å, and with Uiso(H) = 1.2Ueq(C,N,O).The reaction of C-substituted anilines, such as nitroanilines, with succinic anhydride yields initially 3-(arylaminocarbonyl)propionic acids, (A) (see scheme), dehydration of which yields the corresponding N-arylsuccinimides, (B). We have recently reported the molecular and supramolecular structures of the three isomeric N-(nitrophenyl)succinimides [(B), where R = NO2; Glidewell et al., 2005]. We have now prepared all three isomeric 3-(nitrophenylaminocarbonyl)propionic acids [(A), where R = NO2], but unfortunately only the 3-nitro isomer has provided crystals suitable for single-crystal
We report here the molecular and supramolecular structures of 3-(3-nitrophenylaminocarbonyl)propionic acid, (I).The molecules of (I) (Fig. 1) are linked into sheets by a combination of an N—H···O═C hydrogen bond, forming the usual amidic C(4) chain, and an O—H···O hydrogen bond, forming the usual centrosymmetric R22(8) (Bernstein et al., 1995) motif characteristic of simple (Table 1). Carboxyl atom O43 in the molecule at (x, y, z) acts as a hydrogen-bond donor to atom O44 in the molecule at (1 - x, 1 - y, 1 - z), so that the reference R22(8) dimer is centred at (1/2, 1/2, 1/2) (Fig. 2). Amide atoms N1 at (x, y, z) and (1 - x, 1 - y, 1 - z), which form part of the dimer centred at (1/2, 1/2, 1/2), acts as a hydrogen-bond donor to amide atoms O1 at (x, 1/2 - y, -1/2 + z) and (1 - x, 1/2 + y, 1.5 - z), respectively, which themselves form parts of the R22(8) dimers centred at (1/2, 0, 0) and (1/2, 1, 1), respectively. Similarly, atoms O1 at (x, y, z) and (1 - x, 1 - y, 1 - z) accept hydrogen bonds from atoms N1 at (x, 1/2 - y, 1/2 + z) and (1 - x, 1/2 + y, 1/2 - z), which are pairs of the dimers centred respectively at (1/2, 0, 1) and (1/2, 1, 0). In this manner each dimer is directly linked to four other dimers via the amidic C(4) chains along [001], so forming a (100) sheet in which centrosymmetric R22(8) and R66(36) rings alternate in chessboard fashion (Fig. 3).
Data collection: SMART (Bruker, 2000); cell
SAINT-Plus (Bruker, 2000); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 and PRPKAPPA (Ferguson, 1999).C10H10N2O5 | F(000) = 496 |
Mr = 238.20 | Dx = 1.441 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 2525 reflections |
a = 6.6765 (4) Å | θ = 2.1–27.6° |
b = 19.7961 (13) Å | µ = 0.12 mm−1 |
c = 9.0675 (5) Å | T = 293 K |
β = 113.595 (4)° | Plate, colourless |
V = 1098.25 (11) Å3 | 0.38 × 0.17 × 0.04 mm |
Z = 4 |
Bruker SMART 1000 CCD area-detector diffractometer | 2525 independent reflections |
Radiation source: fine-focus sealed X-ray tube | 1537 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.038 |
ω scans | θmax = 27.6°, θmin = 2.1° |
Absorption correction: multi-scan (SADABS; Bruker, 2000) | h = −8→8 |
Tmin = 0.967, Tmax = 0.995 | k = −25→25 |
9375 measured reflections | l = −11→9 |
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)] = 0.044 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.115 | H-atom parameters constrained |
S = 0.91 | w = 1/[σ2(Fo2) + (0.0652P)2] where P = (Fo2 + 2Fc2)/3 |
2525 reflections | (Δ/σ)max < 0.001 |
162 parameters | Δρmax = 0.15 e Å−3 |
0 restraints | Δρmin = −0.22 e Å−3 |
C10H10N2O5 | V = 1098.25 (11) Å3 |
Mr = 238.20 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 6.6765 (4) Å | µ = 0.12 mm−1 |
b = 19.7961 (13) Å | T = 293 K |
c = 9.0675 (5) Å | 0.38 × 0.17 × 0.04 mm |
β = 113.595 (4)° |
Bruker SMART 1000 CCD area-detector diffractometer | 2525 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2000) | 1537 reflections with I > 2σ(I) |
Tmin = 0.967, Tmax = 0.995 | Rint = 0.038 |
9375 measured reflections |
R[F2 > 2σ(F2)] = 0.044 | 0 restraints |
wR(F2) = 0.115 | H-atom parameters constrained |
S = 0.91 | Δρmax = 0.15 e Å−3 |
2525 reflections | Δρmin = −0.22 e Å−3 |
162 parameters |
x | y | z | Uiso*/Ueq | ||
O1 | 0.6360 (2) | 0.29810 (6) | 0.56794 (13) | 0.0575 (3) | |
O31 | 0.0969 (3) | 0.19919 (8) | 0.6589 (2) | 0.0904 (5) | |
O32 | −0.0117 (2) | 0.09628 (8) | 0.6223 (2) | 0.0893 (5) | |
O43 | 0.7815 (2) | 0.47720 (7) | 0.61217 (16) | 0.0787 (4) | |
O44 | 0.5264 (2) | 0.43856 (6) | 0.38524 (15) | 0.0678 (4) | |
N1 | 0.5794 (2) | 0.22718 (7) | 0.35833 (16) | 0.0483 (4) | |
N13 | 0.0921 (2) | 0.14318 (8) | 0.60141 (19) | 0.0603 (4) | |
C1 | 0.6608 (3) | 0.28337 (8) | 0.44555 (19) | 0.0435 (4) | |
C2 | 0.7889 (3) | 0.32755 (8) | 0.3793 (2) | 0.0522 (4) | |
C3 | 0.8823 (3) | 0.38893 (9) | 0.4831 (2) | 0.0591 (5) | |
C4 | 0.7125 (3) | 0.43650 (8) | 0.4891 (2) | 0.0532 (4) | |
C11 | 0.4565 (3) | 0.17529 (8) | 0.39002 (18) | 0.0427 (4) | |
C12 | 0.3293 (2) | 0.18641 (8) | 0.47620 (19) | 0.0441 (4) | |
C13 | 0.2191 (2) | 0.13195 (8) | 0.50369 (19) | 0.0464 (4) | |
C14 | 0.2248 (3) | 0.06807 (9) | 0.4459 (2) | 0.0569 (5) | |
C15 | 0.3478 (3) | 0.05859 (9) | 0.3576 (2) | 0.0622 (5) | |
C16 | 0.4634 (3) | 0.11115 (9) | 0.3298 (2) | 0.0556 (4) | |
H1 | 0.6095 | 0.2191 | 0.2727 | 0.058* | |
H2A | 0.6943 | 0.3421 | 0.2716 | 0.059 (5)* | |
H2B | 0.9073 | 0.3014 | 0.3716 | 0.068 (5)* | |
H3A | 0.9720 | 0.3741 | 0.5917 | 0.067 (5)* | |
H3B | 0.9763 | 0.4128 | 0.4423 | 0.074 (6)* | |
H12 | 0.3183 | 0.2292 | 0.5146 | 0.050 (4)* | |
H14 | 0.1479 | 0.0326 | 0.4660 | 0.073 (6)* | |
H15 | 0.3534 | 0.0160 | 0.3159 | 0.076 (6)* | |
H16 | 0.5468 | 0.1037 | 0.2702 | 0.069 (6)* | |
H43 | 0.6813 | 0.5022 | 0.6082 | 0.094* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0883 (9) | 0.0563 (7) | 0.0480 (7) | −0.0122 (6) | 0.0483 (7) | −0.0082 (5) |
O31 | 0.1100 (12) | 0.0823 (10) | 0.1222 (13) | −0.0204 (8) | 0.0920 (11) | −0.0257 (9) |
O32 | 0.0977 (10) | 0.0837 (10) | 0.1189 (13) | −0.0270 (8) | 0.0775 (10) | −0.0017 (9) |
O43 | 0.0750 (9) | 0.0744 (9) | 0.0763 (9) | −0.0001 (7) | 0.0191 (7) | −0.0268 (8) |
O44 | 0.0728 (9) | 0.0643 (8) | 0.0584 (8) | 0.0009 (6) | 0.0181 (7) | −0.0069 (6) |
N1 | 0.0629 (8) | 0.0554 (8) | 0.0410 (7) | −0.0074 (6) | 0.0357 (7) | −0.0065 (6) |
N13 | 0.0582 (9) | 0.0686 (10) | 0.0668 (10) | −0.0079 (8) | 0.0383 (8) | −0.0006 (8) |
C1 | 0.0540 (9) | 0.0471 (9) | 0.0378 (8) | 0.0018 (7) | 0.0272 (7) | 0.0029 (7) |
C2 | 0.0637 (10) | 0.0556 (10) | 0.0512 (10) | −0.0067 (8) | 0.0377 (9) | −0.0014 (8) |
C3 | 0.0618 (10) | 0.0627 (11) | 0.0615 (12) | −0.0149 (9) | 0.0338 (9) | −0.0038 (9) |
C4 | 0.0683 (11) | 0.0470 (9) | 0.0509 (10) | −0.0139 (8) | 0.0310 (9) | −0.0015 (8) |
C11 | 0.0500 (8) | 0.0477 (8) | 0.0347 (8) | −0.0018 (7) | 0.0216 (7) | −0.0009 (7) |
C12 | 0.0488 (9) | 0.0454 (9) | 0.0432 (9) | −0.0007 (7) | 0.0238 (7) | −0.0026 (7) |
C13 | 0.0444 (8) | 0.0553 (9) | 0.0431 (9) | −0.0025 (7) | 0.0212 (7) | 0.0024 (7) |
C14 | 0.0643 (11) | 0.0503 (10) | 0.0590 (11) | −0.0109 (8) | 0.0278 (9) | −0.0012 (8) |
C15 | 0.0809 (12) | 0.0473 (10) | 0.0633 (12) | −0.0040 (9) | 0.0342 (10) | −0.0104 (9) |
C16 | 0.0680 (11) | 0.0572 (10) | 0.0525 (10) | −0.0005 (8) | 0.0357 (9) | −0.0093 (8) |
N1—C1 | 1.347 (2) | C14—H14 | 0.93 |
N1—C11 | 1.4145 (19) | C15—C16 | 1.377 (2) |
N1—H1 | 0.89 | C15—H15 | 0.9304 |
C1—O1 | 1.2214 (17) | C16—H16 | 0.93 |
C1—C2 | 1.506 (2) | C2—C3 | 1.511 (2) |
C11—C12 | 1.382 (2) | C2—H2A | 0.97 |
C11—C16 | 1.390 (2) | C2—H2B | 0.97 |
C12—C13 | 1.383 (2) | C3—C4 | 1.491 (3) |
C12—H12 | 0.93 | C3—H3A | 0.97 |
C13—C14 | 1.375 (2) | C3—H3B | 0.97 |
C13—N13 | 1.468 (2) | C4—O44 | 1.223 (2) |
N13—O32 | 1.2180 (18) | C4—O43 | 1.302 (2) |
N13—O31 | 1.2201 (19) | O43—H43 | 0.82 |
C14—C15 | 1.370 (2) | ||
C1—N1—C11 | 127.67 (13) | C14—C15—H15 | 119.5 |
C1—N1—H1 | 118.8 | C16—C15—H15 | 119.6 |
C11—N1—H1 | 113.5 | C15—C16—C11 | 120.61 (16) |
O1—C1—N1 | 124.13 (14) | C15—C16—H16 | 119.7 |
O1—C1—C2 | 121.94 (15) | C11—C16—H16 | 119.7 |
N1—C1—C2 | 113.93 (13) | C1—C2—C3 | 112.19 (13) |
C12—C11—C16 | 119.47 (14) | C1—C2—H2A | 109.2 |
C12—C11—N1 | 122.47 (14) | C3—C2—H2A | 109.2 |
C16—C11—N1 | 118.05 (14) | C1—C2—H2B | 109.1 |
C11—C12—C13 | 117.97 (14) | C3—C2—H2B | 109.2 |
C11—C12—H12 | 121.0 | H2A—C2—H2B | 107.9 |
C13—C12—H12 | 121.0 | C4—C3—C2 | 113.60 (15) |
C14—C13—C12 | 123.39 (15) | C4—C3—H3A | 108.9 |
C14—C13—N13 | 118.69 (14) | C2—C3—H3A | 108.8 |
C12—C13—N13 | 117.91 (15) | C4—C3—H3B | 108.9 |
O32—N13—O31 | 123.06 (16) | C2—C3—H3B | 108.9 |
O32—N13—C13 | 118.72 (16) | H3A—C3—H3B | 107.7 |
O31—N13—C13 | 118.22 (14) | O44—C4—O43 | 122.76 (17) |
C15—C14—C13 | 117.59 (15) | O44—C4—C3 | 123.07 (16) |
C15—C14—H14 | 121.2 | O43—C4—C3 | 114.13 (16) |
C13—C14—H14 | 121.2 | C4—O43—H43 | 109.4 |
C14—C15—C16 | 120.93 (16) | ||
C11—N1—C1—O1 | −1.0 (3) | C12—C13—C14—C15 | 0.5 (3) |
C11—N1—C1—C2 | 178.73 (15) | N13—C13—C14—C15 | −178.77 (15) |
C1—N1—C11—C12 | 26.7 (2) | C13—C14—C15—C16 | 0.8 (3) |
C1—N1—C11—C16 | −154.11 (17) | C14—C15—C16—C11 | −0.5 (3) |
C16—C11—C12—C13 | 2.2 (2) | C12—C11—C16—C15 | −1.0 (3) |
N1—C11—C12—C13 | −178.59 (14) | N1—C11—C16—C15 | 179.69 (16) |
C11—C12—C13—C14 | −1.9 (2) | O1—C1—C2—C3 | 1.3 (2) |
C11—C12—C13—N13 | 177.29 (14) | N1—C1—C2—C3 | −178.43 (15) |
C14—C13—N13—O32 | −3.1 (2) | C1—C2—C3—C4 | −64.9 (2) |
C12—C13—N13—O32 | 177.59 (16) | C2—C3—C4—O44 | −22.3 (2) |
C14—C13—N13—O31 | 176.42 (18) | C2—C3—C4—O43 | 159.71 (15) |
C12—C13—N13—O31 | −2.9 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···O1i | 0.89 | 1.96 | 2.850 (2) | 173 |
O43—H43···O44ii | 0.82 | 1.84 | 2.654 (2) | 175 |
Symmetry codes: (i) x, −y+1/2, z−1/2; (ii) −x+1, −y+1, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C10H10N2O5 |
Mr | 238.20 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 293 |
a, b, c (Å) | 6.6765 (4), 19.7961 (13), 9.0675 (5) |
β (°) | 113.595 (4) |
V (Å3) | 1098.25 (11) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.12 |
Crystal size (mm) | 0.38 × 0.17 × 0.04 |
Data collection | |
Diffractometer | Bruker SMART 1000 CCD area-detector |
Absorption correction | Multi-scan (SADABS; Bruker, 2000) |
Tmin, Tmax | 0.967, 0.995 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 9375, 2525, 1537 |
Rint | 0.038 |
(sin θ/λ)max (Å−1) | 0.651 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.044, 0.115, 0.91 |
No. of reflections | 2525 |
No. of parameters | 162 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.15, −0.22 |
Computer programs: SMART (Bruker, 2000), SAINT-Plus (Bruker, 2000), SAINT-Plus, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), PLATON (Spek, 2003), SHELXL97 and PRPKAPPA (Ferguson, 1999).
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···O1i | 0.89 | 1.96 | 2.850 (2) | 173 |
O43—H43···O44ii | 0.82 | 1.84 | 2.654 (2) | 175 |
Symmetry codes: (i) x, −y+1/2, z−1/2; (ii) −x+1, −y+1, −z+1. |
Acknowledgements
The authors thank the University of Aberdeen for funding the purchase of the diffractometer. JLW thanks CNPq and FAPERJ for financial support.
References
Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555–1573. CrossRef CAS Web of Science Google Scholar
Bruker (2000). SMART (Version 5.624), SAINT-Plus (Version 6.02A) and SADABS (Version 2.03). Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Ferguson, G. (1999). PRPKAPPA. University of Guelph, Canada. Google Scholar
Glidewell, C., Low, J. N., Skakle, J. M. S. & Wardell, J. L. (2005). Acta Cryst. C61, o216–o220. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany. Google Scholar
Spek, A. L. (2003). J. Appl. Cryst. 36, 7–13. Web of Science CrossRef CAS IUCr Journals Google Scholar
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The reaction of C-substituted anilines, such as nitroanilines, with succinic anhydride yields initially 3-(arylaminocarbonyl)propionic acids, (A) (see scheme), dehydration of which yields the corresponding N-arylsuccinimides, (B). We have recently reported the molecular and supramolecular structures of the three isomeric N-(nitrophenyl)succinimides [(B), where R = NO2; Glidewell et al., 2005]. We have now prepared all three isomeric 3-(nitrophenylaminocarbonyl)propionic acids [(A), where R = NO2], but unfortunately only the 3-nitro isomer has provided crystals suitable for single-crystal structure determination. We report here the molecular and supramolecular structures of 3-(3-nitrophenylaminocarbonyl)propionic acid, (I).
The molecules of (I) (Fig. 1) are linked into sheets by a combination of an N—H···O═C hydrogen bond, forming the usual amidic C(4) chain, and an O—H···O hydrogen bond, forming the usual centrosymmetric R22(8) (Bernstein et al., 1995) motif characteristic of simple carboxylic acids (Table 1). Carboxyl atom O43 in the molecule at (x, y, z) acts as a hydrogen-bond donor to atom O44 in the molecule at (1 - x, 1 - y, 1 - z), so that the reference R22(8) dimer is centred at (1/2, 1/2, 1/2) (Fig. 2). Amide atoms N1 at (x, y, z) and (1 - x, 1 - y, 1 - z), which form part of the dimer centred at (1/2, 1/2, 1/2), acts as a hydrogen-bond donor to amide atoms O1 at (x, 1/2 - y, -1/2 + z) and (1 - x, 1/2 + y, 1.5 - z), respectively, which themselves form parts of the R22(8) dimers centred at (1/2, 0, 0) and (1/2, 1, 1), respectively. Similarly, atoms O1 at (x, y, z) and (1 - x, 1 - y, 1 - z) accept hydrogen bonds from atoms N1 at (x, 1/2 - y, 1/2 + z) and (1 - x, 1/2 + y, 1/2 - z), which are pairs of the dimers centred respectively at (1/2, 0, 1) and (1/2, 1, 0). In this manner each dimer is directly linked to four other dimers via the amidic C(4) chains along [001], so forming a (100) sheet in which centrosymmetric R22(8) and R66(36) rings alternate in chessboard fashion (Fig. 3).