Comment
Tuberculosis is again a worldwide problem, due in part to the advent of multi-drug resistant strains and the association of tuberculosis with human immunodeficiency virus infection in AIDS. A first-line drug used in combination with other drugs
for the treatment of tuberculosis is isoniazid (isonicotinoylhydrazine). As part of a study of new derivatives of isoniazid, we now report the structures of 2,4-difluorobenzaldehyde isonicotinoylhydrazone, (I)
![[link]](../../../../../../logos/arrows/c_arr.gif)
, and 2,3-dichlorobenzaldehyde isonicotinoylhydrazone, (II)
![[link]](../../../../../../logos/arrows/c_arr.gif)
.
The leading torsion angles (Table 1
) indicate that, while the molecules of compound (II)
are nearly planar, in those of compound (I)
not only is the central spacer unit between atoms C14 and C21 non-planar, but each of the rings, particularly the pyridyl ring, is twisted away from the mean plane of the adjacent spacer atoms.
Compound (I)
(Fig. 1
) exhibits orientational disorder of the difluorinated ring, such that one of the F atoms appears to be disordered over sites bonded to C22 and C26. The major conformer, with this F atom occupying the site designated F2, has occupancy 0.760 (3), while the minor conformer, with the disordered F atom occupying the site designated F6, has occupancy 0.240 (3).
The molecules of compound (I)
are linked by a combination of N—H⋯O and C—H⋯O hydrogen bonds (Table 2
) into a chain of rings, and these chains are linked into sheets by a single π–π stacking interaction. Atoms N17 and C27 in the molecule at (x, y, z) both act as hydrogen-bond donors to atom O1 in the molecule at (
+ x,
− y,
+ z), so forming a C(4)C(7)[R21(6)] chain of rings (Bernstein et al., 1995
) running parallel to the [101] direction and generated by the n-glide plane at y =
(Fig. 2
).
The aryl ring in the molecule at (x, y, z) and the pyridyl ring in the molecules at (
+ x,
− y, −
+ z) and (−
+ x,
− y,
+ z) are almost parallel, with a dihedral angle of only 0.6 (2)° between adjacent rings; the corresponding ring–centroid separations are 3.754 (2) Å, with an interplanar spacing of ca 3.394 Å and a ring offset of ca 1.60 Å. This interaction thus forms a chain parallel to the [10
] direction, which links the hydrogen-bonded [101] chains into an (010) sheet lying in the domain −0.01 < y < 0.51 (Fig. 3
). A second such sheet, related to the first by inversion and generated by the n-glide plane at y =
, lies in the domain 0.49 < y < 1.01, but there are no direction-specific interactions between adjacent (010 sheets.
The molecules of compound (II)
(Fig. 4
) are fully ordered, and they are linked into sheets by a combination of N—H⋯N, C—H⋯N and C—H⋯O hydrogen bonds. Atoms N17 and C13 in the molecule at (x, y, z) both act as hydrogen-bond donors to pyridyl atom N11 in the molecule at (1 − x, −
+ y,
− z), so forming a C(4)C(7)[R21(7)] chain of rings running parallel to the [010] direction and generated by the 21 screw axis along (
, y,
) (Fig. 5
). In addition, atom C12 in the molecule at (x, y, z) acts as hydrogen-bond donor to atom O1 in the molecule at (x,
− y, −
+ z), so forming a C(6) chain running parallel to the [001] direction and generated by the c-glide plane at y =
(Fig. 6
). The combination of the [010] and [001] chains then generates a sheet parallel to (100) containing alternating R44(14) and R44(26) rings, where each type of ring is centrosymmetric (Fig. 7
). There are no direction-specific interactions between adjacent sheets.
| Figure 1 The major conformer (see Comment) of compound (I) , showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. |
| Figure 2 Part of the crystal structure of compound (I) , showing the formation of a chain of rings along [101]. For the sake of clarity, only the major conformer is shown, and H atoms not involved in the motif shown have been omitted. Atoms marked with an asterisk (*) or a hash (#) are at the symmetry positions ( + x, − y, + z) and (− + x, − y, − + z), respectively. |
| Figure 3 A stereoview of part of the crystal structure of compound (I) , showing the formation of an (010) sheet of π-stacked [10 ] chains. For the sake of clarity, only the major conformer is shown and H atoms not involved in the motifs shown have been omitted. |
| Figure 4 The molecule of compound (II) , showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. |
| Figure 5 Part of the crystal structure of compound (II) , showing the formation of a chain of rings along [010]. For the sake of clarity, H atoms not involved in the motif shown have been omitted. Atoms marked with an asterisk (*) or a hash (#) are at the symmetry positions (1 − x, − + y, − z) and (1 − x, + y, − z), respectively. |
| Figure 6 Part of the crystal structure of compound (II) , showing the formation of a C(6) chain along [001]. For the sake of clarity, H atoms not involved in the motif shown have been omitted. Atoms marked with an asterisk (*) or a hash (#) are at the symmetry positions (x, − y, − + z) and (x, − y, + z), respectively. |
| Figure 7 A stereoview of part of the crystal structure of compound (II) , showing the formation of a hydrogen-bonded (100) sheet. For the sake of clarity, H atoms not involved in the motifs shown have been omitted. |
Experimental
Equimolar mixtures of isoniazid (2 mmol) and the appropriate dihalobenzaldehyde (2 mmol) in tetrahydrofuran (20 ml) containing a catalytic amount of triethylamine were heated under reflux for 6 h in an atmosphere of dinitrogen. After cooling, the mixtures were concentrated under reduced pressure and the residues were purified by column chromatography on silica gel, eluting with a hexane–ethyl acetate gradient, to give pure samples of compounds (I)
and (II)
. Crystallization from ethanol solutions gave crystals suitable for single-crystal X-ray diffraction. For (I)
, m.p. 501–503 K; for (II)
, m.p. 511–512 K. Spectroscopic analysis, for (I)
: 1H NMR (DMSO-d6): δ 12.43 (1H, s, NH), 8.82 (2H, d, J = 5.5 Hz), 8.67 (1H, s), 8.02 (1H, dd, J = 15.5 and 8.5 Hz), 7.85 (2H, d, J = 5.5 Hz), 7.40 (1H, dd, J = 9.5 and 11.0 Hz), 7.23 (1H, dd, J = 8.5 and 8.5 Hz); 13C NMR (DMSO-d6): δ: 163.4 (dd, J = 13.2 and 250.5 Hz), 161.6, 161.1 (dd, J = 11.1 and 251.4 Hz), 150.4, 140.9, 140.1, 128.0 (d, J = 8.2 Hz), 121.4, 118.4 (d, J = 10.1 Hz), 112.7 (d, J = 21.9 Hz), 104.5 (t, J = 25.5 Hz); for (II)
: 1H NMR (DMSO-d6): δ 12.35 (1H, s, NH), 8.88 (1H, s), 8.79 (2H, d, J = 5.5 Hz), 7.98 (1H, d, J = 8.0 Hz), 7.83 (2H, d, J = 5.5 Hz), 7.71 (1H, d, J = 7.5 Hz), 7.45 (1H, dd, J = 7.5 and 8.0 Hz); 13C NMR (DMSO-d6): δ 161.7, 150.4, 149.6, 144.6, 140.0, 133.7, 132.4, 131.8, 128.5, 125.6, 121.5; IR (KBr, ν, cm−1), for (I)
: 3177 (NH) and 1654 (CO); for (II)
: 3188 (NH) and 1686 (CO).
Compound (I)![[link]](../../../../../../logos/arrows/c_arr.gif)
Data collection
Nonius KappaCCD area-detector diffractometer φ and ω scans Absorption correction: multi-scan(SADABS; Sheldrick, 2003 )Tmin = 0.946, Tmax = 0.988 10256 measured reflections 2658 independent reflections 2231 reflections with I > 2σ(I) Rint = 0.031 θmax = 27.5° h = −8 → 8 k = −32 → 30 l = −9 → 9
|
| (I) ![[link]](../../../../../../logos/arrows/c_arr.gif) | (II) ![[link]](../../../../../../logos/arrows/c_arr.gif) | C13—C14—C17—N17 | 39.21 (19) | −1.9 (2) | C14—C17—N17—N27 | 178.39 (12) | −175.12 (12) | C17—N17—N27—C27 | 169.28 (13) | 176.30 (13) | N17—N27—C27—C21 | 176.72 (12) | −178.28 (12) | N27—C27—C21—C22 | 168.76 (14) | −173.32 (13) | | |
D—H⋯A | D—H | H⋯A | D⋯A | D—H⋯A | N17—H17⋯O1i | 0.88 | 1.97 | 2.826 (2) | 164 | C27—H27⋯O1i | 0.95 | 2.49 | 3.261 (2) | 138 | Symmetry code: (i) . | |
Compound (II)![[link]](../../../../../../logos/arrows/c_arr.gif)
Data collection
Nonius KappaCCD area-detector diffractometer φ and ω scans Absorption correction: multi-scan(SADABS; Sheldrick, 2003 )Tmin = 0.861, Tmax = 0.965 18370 measured reflections 2833 independent reflections 2466 reflections with I > 2σ(I) Rint = 0.033 θmax = 27.5° h = −10 → 9 k = −13 → 13 l = −19 → 19
|
D—H⋯A | D—H | H⋯A | D⋯A | D—H⋯A | N17—H17⋯N11i | 0.88 | 2.22 | 3.079 (2) | 164 | C12—H12⋯O1ii | 0.95 | 2.45 | 3.338 (2) | 155 | C13—H13⋯N11i | 0.95 | 2.59 | 3.512 (2) | 164 | Symmetry codes: (i) ; (ii) . | |
The space groups P21/n for (I)
and P21/c for (II)
were uniquely assigned from the systematic absences. All H atoms were located in difference maps and then treated as riding atoms, with distances C—H = 0.95 Å and N—H = 0.88 Å, and with Uiso(H) = 1.2Ueq(C,N). In compound (I)
, the disordered difluorinated ring was modelled using partially occupied hydrogen and fluorine sites adjacent to atoms C22 and C26, with the occupancies of the partially occupied hydrogen and partially occupied fluorine sites each constrained to sum to unity. The site-occupancy factors then refined to 0.760 (3) and 0.240 (3).
For both compounds, data collection: COLLECT (Nonius, 1999
); cell refinement: DENZO (Otwinowski & Minor, 1997
) and COLLECT; data reduction: DENZO and COLLECT; program(s) used to solve structure: OSCAIL (McArdle, 2003
) and SHELXS97 (Sheldrick, 1997
); program(s) used to refine structure: OSCAIL and SHELXL97 (Sheldrick, 1997
); molecular graphics: PLATON (Spek, 2003
); software used to prepare material for publication: SHELXL97 and PRPKAPPA (Ferguson, 1999
).
Supporting information
Equimolar mixtures of isoniazid (2 mmol) and the appropriate dihalobenzaldehyde (2 mmol) in tetrahydrofuran (20 ml) containing a catalytic quantity of triethylamine were heated under reflux for 6 h in an atmosphere of dinitrogen. After cooling, the mixtures were concentrated under reduced pressure and the residues were purified by column chromatography on silica gel, eluting with hexane–ethyl acetate gradient, to give pure samples of compounds (I) and (II). Crystallization from ethanol solutions gave crystals suitable for single-crystal X-ray diffraction. For (I), m.p. 501–503 K; for (II), m.p. 511–512 K. Spectroscopic analysis, for (I): 1H NMR (DMSO-d6, δ, p.p.m.): 12.43 (1H, s, NH), 8.82 (2H, d, J = 5.5 Hz), 8.67 (1H, s), 8.02 (1H, dd, J = 15.5 and 8.5 Hz), 7.85 (2H, d, J = 5.5 Hz), 7.40 (1H, dd, J = 9.5 and 11.0 Hz), 7.23 (1H, dd, J= 8.5 and 8.5 Hz); 13C NMR (DMSO-d6, δ, p.p.m.): 163.4 (dd, J = 13.2 and 250.5 Hz), 161.6, 161.1 (dd, J = 11.1 and 251.4 Hz) 150.4, 140.9, 140.1, 128.0 (d, J = 8.2 Hz), 121.4, 118.4 (d, J = 10.1 Hz), 112.7 (d, J = 21.9 Hz), 104.5 (t, J = 25.5 Hz); for (II): 1H NMR (DMSO-d6, δ, p.p.m.): 12.35 (1H, s, NH), 8.88 (1H, s), 8.79 (2H, d, J = 5.5 Hz), 7.98 (1H, d, J = 8.0 Hz), 7.83 (2H, d, J = 5.5 Hz), 7.71 (1H, d, J = 7.5 Hz), 7.45 (1H, dd, J = 7.5 and 8.0 Hz); 13C NMR (DMSO-d6, δ, p.p.m.): 161.7, 150.4, 149.6, 144.6, 140.0, 133.7, 132.4, 131.8, 128.5, 125.6, 121.5; IR (KBr, ν, cm−1), for (I): 3177 (NH) and 1654 (CO); for (II): 3188 (NH) and 1686 (CO).
The space groups P21/n for (I) and P21/c for (II) were uniquely assigned from the systematic absences. All H atoms were located in difference maps and then treated as riding atoms, with distances C—H = 0.95 Å and N—H = 0.88 Å, and with Uiso(H) = 1.2Ueq(C,N). In compound (I), the disordered difluorinated ring was modelled using partially occupied H and F sites adjacent to atoms C22 and C26, with the occupancies of the partially occupied H and partially occupied F sites each constrained to sum to unity. The site-occupancy factors then refined to 0.760 (3) and 0.240 (3).
For both compounds, data collection: COLLECT (Nonius, 1999); cell refinement: DENZO (Otwinowski & Minor, 1997) and COLLECT; data reduction: DENZO and COLLECT; program(s) used to solve structure: OSCAIL (McArdle, 2003) and SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: OSCAIL and SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 and PRPKAPPA (Ferguson, 1999).
(I) 2,4-difluorobenzaldehyde isonicotinoylhydrazone
top Crystal data top C13H9F2N3O | F(000) = 536 |
Mr = 261.23 | Dx = 1.476 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 2658 reflections |
a = 6.8859 (3) Å | θ = 3.2–27.5° |
b = 24.7258 (12) Å | µ = 0.12 mm−1 |
c = 7.2582 (2) Å | T = 120 K |
β = 107.953 (2)° | Block, colourless |
V = 1175.61 (8) Å3 | 0.60 × 0.35 × 0.10 mm |
Z = 4 | |
Data collection top Nonius KappaCCD area-detector diffractometer | 2658 independent reflections |
Radiation source: Bruker-Nonius FR91 rotating anode | 2231 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.031 |
Detector resolution: 9.091 pixels mm-1 | θmax = 27.5°, θmin = 3.2° |
ϕ and ω scans | h = −8→8 |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | k = −32→30 |
Tmin = 0.946, Tmax = 0.988 | l = −9→9 |
10256 measured reflections | |
Refinement top 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)] = 0.041 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.101 | H-atom parameters constrained |
S = 1.07 | w = 1/[σ2(Fo2) + (0.035P)2 + 0.6726P] where P = (Fo2 + 2Fc2)/3 |
2658 reflections | (Δ/σ)max = 0.001 |
178 parameters | Δρmax = 0.25 e Å−3 |
0 restraints | Δρmin = −0.28 e Å−3 |
Crystal data top C13H9F2N3O | V = 1175.61 (8) Å3 |
Mr = 261.23 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 6.8859 (3) Å | µ = 0.12 mm−1 |
b = 24.7258 (12) Å | T = 120 K |
c = 7.2582 (2) Å | 0.60 × 0.35 × 0.10 mm |
β = 107.953 (2)° | |
Data collection top Nonius KappaCCD area-detector diffractometer | 2658 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | 2231 reflections with I > 2σ(I) |
Tmin = 0.946, Tmax = 0.988 | Rint = 0.031 |
10256 measured reflections | |
Refinement top R[F2 > 2σ(F2)] = 0.041 | 0 restraints |
wR(F2) = 0.101 | H-atom parameters constrained |
S = 1.07 | Δρmax = 0.25 e Å−3 |
2658 reflections | Δρmin = −0.28 e Å−3 |
178 parameters | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
F2 | 0.8073 (2) | 0.45076 (5) | 0.56591 (17) | 0.0346 (4) | 0.760 (3) |
F4 | 0.72835 (17) | 0.50298 (4) | −0.07066 (15) | 0.0403 (3) | |
F6 | 0.6083 (6) | 0.32559 (14) | 0.0544 (5) | 0.0317 (13) | 0.240 (3) |
O1 | 0.51293 (16) | 0.19391 (4) | 0.41215 (14) | 0.0219 (2) | |
N11 | 0.7884 (2) | 0.10916 (5) | 1.06980 (18) | 0.0258 (3) | |
N17 | 0.72223 (19) | 0.25953 (5) | 0.58717 (16) | 0.0192 (3) | |
N27 | 0.68464 (18) | 0.29395 (5) | 0.42872 (17) | 0.0189 (3) | |
C12 | 0.7607 (2) | 0.16247 (6) | 1.0840 (2) | 0.0238 (3) | |
C13 | 0.7125 (2) | 0.19749 (6) | 0.9274 (2) | 0.0198 (3) | |
C14 | 0.6889 (2) | 0.17639 (6) | 0.74432 (19) | 0.0169 (3) | |
C15 | 0.7128 (2) | 0.12117 (6) | 0.7257 (2) | 0.0187 (3) | |
C16 | 0.7642 (2) | 0.08966 (6) | 0.8920 (2) | 0.0235 (3) | |
C17 | 0.6327 (2) | 0.21063 (5) | 0.56489 (19) | 0.0180 (4) | |
C21 | 0.7347 (2) | 0.38328 (6) | 0.3252 (2) | 0.0174 (3) | |
C22 | 0.7742 (2) | 0.43710 (6) | 0.3791 (2) | 0.0236 (3) | |
C23 | 0.7718 (3) | 0.47825 (6) | 0.2506 (2) | 0.0286 (4) | |
C24 | 0.7276 (2) | 0.46374 (6) | 0.0597 (2) | 0.0261 (3) | |
C25 | 0.6819 (2) | 0.41167 (7) | −0.0066 (2) | 0.0266 (3) | |
C26 | 0.6863 (2) | 0.37187 (6) | 0.1282 (2) | 0.0226 (3) | |
C27 | 0.7506 (2) | 0.34208 (6) | 0.4739 (2) | 0.0181 (3) | |
H12 | 0.7751 | 0.1771 | 1.2086 | 0.029* | |
H13 | 0.6958 | 0.2351 | 0.9447 | 0.024* | |
H15 | 0.6944 | 0.1053 | 0.6023 | 0.022* | |
H16 | 0.7835 | 0.0520 | 0.8790 | 0.028* | |
H17 | 0.8159 | 0.2677 | 0.6969 | 0.023* | |
H27 | 0.8111 | 0.3512 | 0.6064 | 0.022* | |
H22 | 0.8046 | 0.4460 | 0.5124 | 0.028* | 0.240 (3) |
H23 | 0.7993 | 0.5147 | 0.2919 | 0.034* | |
H25 | 0.6485 | 0.4034 | −0.1406 | 0.032* | |
H26 | 0.6555 | 0.3356 | 0.0855 | 0.038* | 0.760 (3) |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
F2 | 0.0587 (9) | 0.0227 (6) | 0.0207 (7) | −0.0062 (6) | 0.0096 (6) | −0.0055 (5) |
F4 | 0.0542 (7) | 0.0306 (5) | 0.0370 (6) | 0.0013 (5) | 0.0155 (5) | 0.0180 (4) |
F6 | 0.053 (3) | 0.0194 (19) | 0.023 (2) | −0.0074 (17) | 0.0115 (18) | −0.0032 (15) |
O1 | 0.0240 (6) | 0.0197 (5) | 0.0173 (5) | −0.0013 (4) | −0.0005 (4) | −0.0002 (4) |
N11 | 0.0278 (7) | 0.0274 (7) | 0.0213 (6) | 0.0004 (5) | 0.0061 (5) | 0.0057 (5) |
N17 | 0.0215 (6) | 0.0182 (6) | 0.0143 (6) | −0.0023 (5) | 0.0001 (5) | 0.0024 (4) |
N27 | 0.0192 (6) | 0.0190 (6) | 0.0175 (6) | 0.0002 (5) | 0.0041 (5) | 0.0042 (5) |
C12 | 0.0249 (8) | 0.0293 (8) | 0.0172 (7) | −0.0025 (6) | 0.0065 (6) | −0.0008 (6) |
C13 | 0.0198 (7) | 0.0194 (7) | 0.0201 (7) | −0.0011 (5) | 0.0060 (6) | −0.0022 (5) |
C14 | 0.0130 (7) | 0.0192 (7) | 0.0176 (7) | −0.0011 (5) | 0.0034 (5) | 0.0013 (5) |
C15 | 0.0182 (7) | 0.0189 (7) | 0.0183 (7) | −0.0011 (5) | 0.0048 (5) | −0.0018 (5) |
C16 | 0.0246 (8) | 0.0193 (7) | 0.0262 (8) | 0.0006 (6) | 0.0073 (6) | 0.0023 (6) |
C17 | 0.0159 (9) | 0.0202 (9) | 0.0164 (9) | 0.0005 (7) | 0.0029 (7) | 0.0004 (7) |
C21 | 0.0139 (6) | 0.0186 (7) | 0.0194 (7) | 0.0005 (5) | 0.0048 (5) | 0.0016 (5) |
C22 | 0.0276 (8) | 0.0228 (7) | 0.0205 (7) | −0.0017 (6) | 0.0073 (6) | −0.0026 (6) |
C23 | 0.0351 (9) | 0.0180 (7) | 0.0335 (9) | −0.0016 (6) | 0.0120 (7) | 0.0010 (6) |
C24 | 0.0264 (8) | 0.0234 (7) | 0.0285 (8) | 0.0027 (6) | 0.0086 (7) | 0.0112 (6) |
C25 | 0.0295 (8) | 0.0311 (8) | 0.0186 (7) | −0.0004 (7) | 0.0064 (6) | 0.0031 (6) |
C26 | 0.0240 (8) | 0.0206 (7) | 0.0227 (7) | −0.0038 (6) | 0.0064 (6) | −0.0016 (6) |
C27 | 0.0163 (7) | 0.0204 (7) | 0.0164 (7) | 0.0004 (5) | 0.0034 (5) | 0.0002 (5) |
Geometric parameters (Å, º) top N11—C16 | 1.339 (2) | C27—C21 | 1.4631 (19) |
N11—C12 | 1.340 (2) | C27—H27 | 0.95 |
C12—C13 | 1.386 (2) | C21—C22 | 1.390 (2) |
C12—H12 | 0.95 | C21—C26 | 1.393 (2) |
C13—C14 | 1.3895 (19) | C22—F2 | 1.3465 (19) |
C13—H13 | 0.95 | C22—C23 | 1.377 (2) |
C14—C15 | 1.387 (2) | C22—H22 | 0.95 |
C14—C17 | 1.5006 (19) | C23—C24 | 1.372 (2) |
C15—C16 | 1.388 (2) | C23—H23 | 0.95 |
C15—H15 | 0.95 | C24—F4 | 1.3564 (17) |
C16—H16 | 0.95 | C24—C25 | 1.377 (2) |
C17—O1 | 1.2315 (17) | C25—C26 | 1.382 (2) |
C17—N17 | 1.3442 (18) | C25—H25 | 0.95 |
N17—N27 | 1.3894 (16) | C26—F6 | 1.307 (4) |
N17—H17 | 0.88 | C26—H26 | 0.95 |
N27—C27 | 1.2799 (18) | | |
| | | |
C16—N11—C12 | 116.74 (13) | N27—C27—H27 | 119.4 |
N11—C12—C13 | 123.73 (14) | C21—C27—H27 | 119.4 |
N11—C12—H12 | 118.1 | C22—C21—C26 | 116.53 (13) |
C13—C12—H12 | 118.1 | C22—C21—C27 | 119.69 (13) |
C12—C13—C14 | 118.54 (14) | C26—C21—C27 | 123.76 (13) |
C12—C13—H13 | 120.7 | F2—C22—C23 | 117.36 (14) |
C14—C13—H13 | 120.7 | F2—C22—C21 | 118.76 (14) |
C15—C14—C13 | 118.70 (13) | C23—C22—C21 | 123.80 (14) |
C15—C14—C17 | 118.54 (12) | C23—C22—H22 | 118.1 |
C13—C14—C17 | 122.74 (13) | C21—C22—H22 | 118.1 |
C14—C15—C16 | 118.32 (13) | C24—C23—C22 | 116.34 (14) |
C14—C15—H15 | 120.8 | C24—C23—H23 | 121.8 |
C16—C15—H15 | 120.8 | C22—C23—H23 | 121.8 |
N11—C16—C15 | 123.96 (14) | F4—C24—C23 | 118.06 (14) |
N11—C16—H16 | 118.0 | F4—C24—C25 | 118.32 (14) |
C15—C16—H16 | 118.0 | C23—C24—C25 | 123.61 (14) |
O1—C17—N17 | 124.42 (13) | C24—C25—C26 | 117.74 (14) |
O1—C17—C14 | 120.92 (12) | C24—C25—H25 | 121.1 |
N17—C17—C14 | 114.65 (12) | C26—C25—H25 | 121.1 |
C17—N17—N27 | 119.34 (11) | F6—C26—C25 | 114.62 (19) |
C17—N17—H17 | 119.8 | F6—C26—C21 | 122.42 (19) |
N27—N17—H17 | 120.4 | C25—C26—C21 | 121.94 (14) |
C27—N27—N17 | 113.36 (11) | C25—C26—H26 | 119.1 |
N27—C27—C21 | 121.22 (13) | C21—C26—H26 | 119.0 |
| | | |
C16—N11—C12—C13 | −0.9 (2) | N27—C27—C21—C26 | −13.0 (2) |
N11—C12—C13—C14 | 0.7 (2) | C26—C21—C22—F2 | 175.32 (14) |
C12—C13—C14—C15 | 0.6 (2) | C27—C21—C22—F2 | −6.3 (2) |
C12—C13—C14—C17 | 178.76 (13) | C26—C21—C22—C23 | −1.3 (2) |
C13—C14—C15—C16 | −1.6 (2) | C27—C21—C22—C23 | 177.04 (15) |
C17—C14—C15—C16 | −179.82 (13) | F2—C22—C23—C24 | −176.81 (15) |
C12—N11—C16—C15 | −0.2 (2) | C21—C22—C23—C24 | −0.1 (2) |
C14—C15—C16—N11 | 1.4 (2) | C22—C23—C24—F4 | −178.56 (14) |
C15—C14—C17—O1 | 37.62 (19) | C22—C23—C24—C25 | 1.7 (3) |
C13—C14—C17—O1 | −140.55 (14) | F4—C24—C25—C26 | 178.55 (14) |
C15—C14—C17—N17 | −142.61 (14) | C23—C24—C25—C26 | −1.7 (3) |
C13—C14—C17—N17 | 39.21 (19) | C24—C25—C26—F6 | 168.8 (2) |
O1—C17—N17—N27 | −1.9 (2) | C24—C25—C26—C21 | 0.1 (2) |
C14—C17—N17—N27 | 178.39 (12) | C22—C21—C26—F6 | −166.5 (2) |
C17—N17—N27—C27 | 169.28 (13) | C27—C21—C26—F6 | 15.2 (3) |
N17—N27—C27—C21 | 176.72 (12) | C22—C21—C26—C25 | 1.3 (2) |
N27—C27—C21—C22 | 168.76 (14) | C27—C21—C26—C25 | −176.98 (14) |
Hydrogen-bond geometry (Å, º) top D—H···A | D—H | H···A | D···A | D—H···A |
N17—H17···O1i | 0.88 | 1.97 | 2.826 (2) | 164 |
C27—H27···O1i | 0.95 | 2.49 | 3.261 (2) | 138 |
Symmetry code: (i) x+1/2, −y+1/2, z+1/2. |
(II) 2,3-dichlorobenzaldehyde isonicotinoylhydrazone
top Crystal data top C13H9Cl2N3O | F(000) = 600 |
Mr = 294.13 | Dx = 1.572 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 2833 reflections |
a = 7.7369 (2) Å | θ = 3.2–27.5° |
b = 10.7764 (4) Å | µ = 0.52 mm−1 |
c = 14.9091 (5) Å | T = 120 K |
β = 90.2400 (18)° | Plate, colourless |
V = 1243.05 (7) Å3 | 0.30 × 0.10 × 0.07 mm |
Z = 4 | |
Data collection top Nonius KappaCCD area-detector diffractometer | 2833 independent reflections |
Radiation source: Bruker-Nonius FR91 rotating anode | 2466 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.033 |
Detector resolution: 9.091 pixels mm-1 | θmax = 27.5°, θmin = 3.2° |
ϕ and ω scans | h = −10→9 |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | k = −13→13 |
Tmin = 0.861, Tmax = 0.965 | l = −19→19 |
18370 measured reflections | |
Refinement top 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)] = 0.031 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.099 | H-atom parameters constrained |
S = 1.15 | w = 1/[σ2(Fo2) + (0.0574P)2 + 0.238P] where P = (Fo2 + 2Fc2)/3 |
2833 reflections | (Δ/σ)max = 0.001 |
172 parameters | Δρmax = 0.42 e Å−3 |
0 restraints | Δρmin = −0.49 e Å−3 |
Crystal data top C13H9Cl2N3O | V = 1243.05 (7) Å3 |
Mr = 294.13 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 7.7369 (2) Å | µ = 0.52 mm−1 |
b = 10.7764 (4) Å | T = 120 K |
c = 14.9091 (5) Å | 0.30 × 0.10 × 0.07 mm |
β = 90.2400 (18)° | |
Data collection top Nonius KappaCCD area-detector diffractometer | 2833 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | 2466 reflections with I > 2σ(I) |
Tmin = 0.861, Tmax = 0.965 | Rint = 0.033 |
18370 measured reflections | |
Refinement top R[F2 > 2σ(F2)] = 0.031 | 0 restraints |
wR(F2) = 0.099 | H-atom parameters constrained |
S = 1.15 | Δρmax = 0.42 e Å−3 |
2833 reflections | Δρmin = −0.49 e Å−3 |
172 parameters | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
Cl2 | 0.04940 (5) | 0.24580 (4) | 0.42803 (2) | 0.02352 (14) | |
Cl3 | −0.10886 (5) | 0.09016 (3) | 0.58410 (3) | 0.02128 (13) | |
O1 | 0.51413 (15) | 0.78229 (11) | 0.53171 (7) | 0.0230 (3) | |
N11 | 0.63516 (16) | 0.99082 (12) | 0.23853 (9) | 0.0196 (3) | |
N17 | 0.39121 (15) | 0.64469 (12) | 0.43497 (8) | 0.0161 (3) | |
N27 | 0.32647 (16) | 0.57712 (11) | 0.50549 (9) | 0.0168 (3) | |
C12 | 0.5589 (2) | 0.88125 (15) | 0.22055 (10) | 0.0199 (3) | |
C13 | 0.5094 (2) | 0.79782 (15) | 0.28652 (10) | 0.0191 (3) | |
C14 | 0.53873 (18) | 0.82704 (14) | 0.37632 (10) | 0.0151 (3) | |
C15 | 0.62092 (19) | 0.93893 (15) | 0.39518 (11) | 0.0185 (3) | |
C16 | 0.6659 (2) | 1.01645 (15) | 0.32536 (11) | 0.0209 (3) | |
C17 | 0.48243 (19) | 0.74973 (13) | 0.45513 (11) | 0.0162 (3) | |
C21 | 0.15624 (18) | 0.40883 (13) | 0.55589 (10) | 0.0150 (3) | |
C22 | 0.06857 (18) | 0.29789 (14) | 0.53716 (10) | 0.0158 (3) | |
C23 | −0.00409 (19) | 0.22879 (14) | 0.60658 (10) | 0.0167 (3) | |
C24 | 0.0077 (2) | 0.26876 (15) | 0.69431 (11) | 0.0220 (3) | |
C25 | 0.0932 (2) | 0.37925 (16) | 0.71337 (11) | 0.0249 (4) | |
C26 | 0.1665 (2) | 0.44816 (15) | 0.64513 (11) | 0.0197 (3) | |
C27 | 0.23389 (18) | 0.48333 (14) | 0.48410 (10) | 0.0163 (3) | |
H12 | 0.5380 | 0.8600 | 0.1596 | 0.024* | |
H13 | 0.4560 | 0.7215 | 0.2706 | 0.023* | |
H15 | 0.6458 | 0.9617 | 0.4554 | 0.022* | |
H16 | 0.7220 | 1.0924 | 0.3395 | 0.025* | |
H17 | 0.3793 | 0.6147 | 0.3804 | 0.019* | |
H24 | −0.0420 | 0.2212 | 0.7413 | 0.026* | |
H25 | 0.1012 | 0.4076 | 0.7736 | 0.030* | |
H26 | 0.2248 | 0.5234 | 0.6591 | 0.024* | |
H27 | 0.2157 | 0.4622 | 0.4229 | 0.020* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Cl2 | 0.0362 (3) | 0.0209 (2) | 0.0135 (2) | −0.00425 (15) | −0.00043 (16) | −0.00294 (14) |
Cl3 | 0.0249 (2) | 0.0160 (2) | 0.0230 (2) | −0.00380 (14) | 0.00022 (15) | 0.00012 (14) |
O1 | 0.0329 (6) | 0.0217 (6) | 0.0143 (6) | −0.0044 (5) | −0.0022 (5) | 0.0003 (5) |
N11 | 0.0241 (7) | 0.0165 (7) | 0.0182 (7) | −0.0001 (5) | 0.0005 (5) | 0.0018 (5) |
N17 | 0.0207 (6) | 0.0152 (6) | 0.0124 (6) | −0.0001 (5) | 0.0011 (5) | 0.0024 (5) |
N27 | 0.0174 (6) | 0.0162 (7) | 0.0167 (7) | 0.0014 (5) | 0.0011 (5) | 0.0032 (5) |
C12 | 0.0260 (8) | 0.0187 (8) | 0.0148 (8) | −0.0005 (6) | −0.0003 (6) | −0.0015 (6) |
C13 | 0.0243 (8) | 0.0159 (8) | 0.0171 (8) | −0.0025 (6) | −0.0009 (6) | −0.0009 (6) |
C14 | 0.0150 (7) | 0.0140 (7) | 0.0163 (8) | 0.0029 (5) | 0.0000 (5) | 0.0016 (6) |
C15 | 0.0220 (7) | 0.0181 (8) | 0.0153 (8) | −0.0004 (6) | −0.0025 (6) | −0.0008 (6) |
C16 | 0.0243 (8) | 0.0187 (8) | 0.0198 (8) | −0.0038 (6) | −0.0017 (6) | −0.0003 (6) |
C17 | 0.0173 (7) | 0.0145 (8) | 0.0168 (8) | 0.0024 (5) | −0.0002 (6) | 0.0014 (6) |
C21 | 0.0154 (7) | 0.0150 (7) | 0.0148 (7) | 0.0036 (5) | 0.0006 (5) | 0.0012 (6) |
C22 | 0.0173 (7) | 0.0171 (8) | 0.0130 (7) | 0.0033 (6) | −0.0019 (5) | −0.0010 (6) |
C23 | 0.0169 (7) | 0.0143 (7) | 0.0187 (8) | 0.0011 (6) | 0.0001 (6) | 0.0003 (6) |
C24 | 0.0264 (8) | 0.0234 (8) | 0.0162 (8) | −0.0026 (6) | 0.0037 (6) | 0.0017 (6) |
C25 | 0.0337 (9) | 0.0265 (9) | 0.0147 (8) | −0.0060 (7) | 0.0013 (7) | −0.0034 (7) |
C26 | 0.0233 (8) | 0.0181 (8) | 0.0175 (8) | −0.0029 (6) | 0.0002 (6) | −0.0023 (6) |
C27 | 0.0176 (7) | 0.0166 (8) | 0.0146 (7) | 0.0032 (6) | 0.0004 (5) | 0.0004 (6) |
Geometric parameters (Å, º) top N11—C16 | 1.344 (2) | N27—C27 | 1.2785 (19) |
N11—C12 | 1.346 (2) | C27—C21 | 1.469 (2) |
C12—C13 | 1.388 (2) | C27—H27 | 0.95 |
C12—H12 | 0.95 | C21—C26 | 1.398 (2) |
C13—C14 | 1.393 (2) | C21—C22 | 1.402 (2) |
C13—H13 | 0.95 | C22—C23 | 1.395 (2) |
C14—C15 | 1.391 (2) | C22—Cl2 | 1.7270 (15) |
C14—C17 | 1.506 (2) | C23—C24 | 1.380 (2) |
C15—C16 | 1.381 (2) | C23—Cl3 | 1.7318 (16) |
C15—H15 | 0.95 | C24—C25 | 1.391 (2) |
C16—H16 | 0.95 | C24—H24 | 0.95 |
C17—O1 | 1.2183 (19) | C25—C26 | 1.383 (2) |
C17—N17 | 1.3667 (19) | C25—H25 | 0.95 |
N17—N27 | 1.3751 (17) | C26—H26 | 0.95 |
N17—H17 | 0.88 | | |
| | | |
C16—N11—C12 | 116.60 (13) | C27—N27—N17 | 115.68 (13) |
N11—C12—C13 | 123.31 (14) | N27—C27—C21 | 118.74 (14) |
N11—C12—H12 | 118.3 | N27—C27—H27 | 120.6 |
C13—C12—H12 | 118.3 | C21—C27—H27 | 120.6 |
C12—C13—C14 | 119.37 (14) | C26—C21—C22 | 118.26 (14) |
C12—C13—H13 | 120.3 | C26—C21—C27 | 120.40 (14) |
C14—C13—H13 | 120.3 | C22—C21—C27 | 121.33 (13) |
C15—C14—C13 | 117.55 (14) | C23—C22—C21 | 120.23 (14) |
C15—C14—C17 | 117.07 (13) | C23—C22—Cl2 | 119.48 (12) |
C13—C14—C17 | 125.33 (14) | C21—C22—Cl2 | 120.29 (11) |
C16—C15—C14 | 119.25 (14) | C24—C23—C22 | 120.75 (14) |
C16—C15—H15 | 120.4 | C24—C23—Cl3 | 118.81 (12) |
C14—C15—H15 | 120.4 | C22—C23—Cl3 | 120.44 (12) |
N11—C16—C15 | 123.89 (15) | C23—C24—C25 | 119.38 (15) |
N11—C16—H16 | 118.1 | C23—C24—H24 | 120.3 |
C15—C16—H16 | 118.1 | C25—C24—H24 | 120.3 |
O1—C17—N17 | 123.12 (14) | C26—C25—C24 | 120.36 (15) |
O1—C17—C14 | 120.92 (13) | C26—C25—H25 | 119.8 |
N17—C17—C14 | 115.93 (13) | C24—C25—H25 | 119.8 |
C17—N17—N27 | 117.38 (13) | C25—C26—C21 | 121.01 (15) |
C17—N17—H17 | 124.0 | C25—C26—H26 | 119.5 |
N27—N17—H17 | 118.4 | C21—C26—H26 | 119.5 |
| | | |
C16—N11—C12—C13 | 1.4 (2) | N27—C27—C21—C26 | 7.4 (2) |
N11—C12—C13—C14 | 0.0 (2) | N27—C27—C21—C22 | −173.32 (13) |
C12—C13—C14—C15 | −1.4 (2) | C26—C21—C22—C23 | −0.8 (2) |
C12—C13—C14—C17 | 176.01 (14) | C27—C21—C22—C23 | 180.00 (13) |
C13—C14—C15—C16 | 1.4 (2) | C26—C21—C22—Cl2 | 179.17 (11) |
C17—C14—C15—C16 | −176.26 (13) | C27—C21—C22—Cl2 | −0.08 (19) |
C12—N11—C16—C15 | −1.4 (2) | C21—C22—C23—C24 | 0.6 (2) |
C14—C15—C16—N11 | 0.0 (2) | Cl2—C22—C23—C24 | −179.36 (12) |
C15—C14—C17—O1 | −2.8 (2) | C21—C22—C23—Cl3 | −178.73 (11) |
C13—C14—C17—O1 | 179.78 (15) | Cl2—C22—C23—Cl3 | 1.35 (18) |
C15—C14—C17—N17 | 175.51 (13) | C22—C23—C24—C25 | 0.0 (2) |
C13—C14—C17—N17 | −1.9 (2) | Cl3—C23—C24—C25 | 179.32 (13) |
O1—C17—N17—N27 | 3.1 (2) | C23—C24—C25—C26 | −0.4 (3) |
C14—C17—N17—N27 | −175.12 (12) | C24—C25—C26—C21 | 0.2 (2) |
C17—N17—N27—C27 | 176.30 (13) | C22—C21—C26—C25 | 0.4 (2) |
N17—N27—C27—C21 | −178.28 (12) | C27—C21—C26—C25 | 179.65 (14) |
Hydrogen-bond geometry (Å, º) top D—H···A | D—H | H···A | D···A | D—H···A |
N17—H17···N11i | 0.88 | 2.22 | 3.079 (2) | 164 |
C12—H12···O1ii | 0.95 | 2.45 | 3.338 (2) | 155 |
C13—H13···N11i | 0.95 | 2.59 | 3.512 (2) | 164 |
Symmetry codes: (i) −x+1, y−1/2, −z+1/2; (ii) x, −y+3/2, z−1/2. |
Experimental details
| (I) | (II) |
Crystal data |
Chemical formula | C13H9F2N3O | C13H9Cl2N3O |
Mr | 261.23 | 294.13 |
Crystal system, space group | Monoclinic, P21/n | Monoclinic, P21/c |
Temperature (K) | 120 | 120 |
a, b, c (Å) | 6.8859 (3), 24.7258 (12), 7.2582 (2) | 7.7369 (2), 10.7764 (4), 14.9091 (5) |
β (°) | 107.953 (2) | 90.2400 (18) |
V (Å3) | 1175.61 (8) | 1243.05 (7) |
Z | 4 | 4 |
Radiation type | Mo Kα | Mo Kα |
µ (mm−1) | 0.12 | 0.52 |
Crystal size (mm) | 0.60 × 0.35 × 0.10 | 0.30 × 0.10 × 0.07 |
|
Data collection |
Diffractometer | Nonius KappaCCD area-detector diffractometer | Nonius KappaCCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 2003) | Multi-scan (SADABS; Sheldrick, 2003) |
Tmin, Tmax | 0.946, 0.988 | 0.861, 0.965 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 10256, 2658, 2231 | 18370, 2833, 2466 |
Rint | 0.031 | 0.033 |
(sin θ/λ)max (Å−1) | 0.649 | 0.649 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.041, 0.101, 1.07 | 0.031, 0.099, 1.15 |
No. of reflections | 2658 | 2833 |
No. of parameters | 178 | 172 |
H-atom treatment | H-atom parameters constrained | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.25, −0.28 | 0.42, −0.49 |
Hydrogen-bond geometry (Å, º) for (I) top D—H···A | D—H | H···A | D···A | D—H···A |
N17—H17···O1i | 0.88 | 1.97 | 2.826 (2) | 164 |
C27—H27···O1i | 0.95 | 2.49 | 3.261 (2) | 138 |
Symmetry code: (i) x+1/2, −y+1/2, z+1/2. |
Hydrogen-bond geometry (Å, º) for (II) top D—H···A | D—H | H···A | D···A | D—H···A |
N17—H17···N11i | 0.88 | 2.22 | 3.079 (2) | 164 |
C12—H12···O1ii | 0.95 | 2.45 | 3.338 (2) | 155 |
C13—H13···N11i | 0.95 | 2.59 | 3.512 (2) | 164 |
Symmetry codes: (i) −x+1, y−1/2, −z+1/2; (ii) x, −y+3/2, z−1/2. |
Selected torsion angles for compounds (I) and (II) (°) topParameter | (I) | (II) |
C13-C14-C17-N17 | 39.21 (19) | -1.9 (2) |
C14-C17-N17-N27 | 178.39 (12) | -175.12 (12) |
C17-N17-N27-C27 | 169.28 (13) | 176.30 (13) |
N17-N27-C27-C21 | 176.72 (12) | -178.28 (12) |
N27-C27-C21-C22 | 168.76 (14) | -173.32 (13) |
Tuberculosis is again a world-wide problem, due in part to the advent of multi-drug resistant strains and the association of tuberculosis with human immunodeficiency virus infection in AIDS. A first-line drug used in combination with other drugs for treatment of tuberculosis is isoniazid (isonitinoylhydrazine). As part of a study of new derivatives of isoniazid, we now report the structures of N-(isonicotinoyl)-2,4-difluorobenzaldehyde hydrazone, (I), and N-(isonicotinoyl)-2,3-dichlorobenzaldehyde hydrazone, (II).
The leading torsion angles (Table 1) indicate that, while the molecules of compound (II) are nearly planar, in those of compound (I) not only is the central spacer unit between atoms C14 and C21 non-planar, but each of the rings, particularly the pyridyl ring, is twisted away from the mean plane of the adjacent spacer atoms.
Compound (I) (Fig. 1) exhibits orientational disorder of the difluorinated ring, such that one of the F atoms appears to be disordered over sites bonded to C22 and C26. The major conformer, with this F atom occupying the site designated F2, has occupancy 0.760 (3), while the minor conformer, with the disordered F atom occupying the site designated F6, has occupancy 0.240 (3).
The molecules of compound (I) are linked by a combination of N—H···O and C—H···O hydrogen bonds (Table 2) into a chain of rings, and these chains are linked into sheets by a single π–π stacking interaction. Atoms N17 and C27 in the molecule at (x, y, z) both act as hydrogen-bond donors to atom O1 in the molecule at (1/2 + x, 1/2 − y, 1/2 + z), so forming a C(4)C(7)[R21(6)] chain of rings (Bernstein et al., 1995) running parallel to the [101] direction and generated by the n-glide plane at y = 1/4 (Fig. 2).
The aryl ring in the molecule at (x, y, z) and the pyridyl ring in the molecules at (1/2 + x, 1/2 − y, −1/2 + z) and (−1/2 + x, 1/2 − y, 1/2 + z) are almost parallel, with a dihedral angle of only 0.6 (2)° between adjacent rings. the corresponding ring–centroid separations are 3.754 (2) Å, with an interplanar spacing of ca 3.394 Å and a ring offset of ca 1.60 Å. This interaction thus forms a chain parallel to the [101] direction, which links the hydrogen-bonded [101] chains into an (010) sheet lying in the domain −0.01 < y < 0.51 (Fig. 3). A second such sheet, related to the first by inversion and generated by the n-glide plane at y = 3/4, lies in the domain 0.49 < y < 1.01, but there are no direction-specific interactions between adjacent (010 sheets.
The molecules of compound (II) (Fig. 4) are fully ordered, and they are linked into sheets by a combination of N—H···N, C—H···N and C—H···O hydrogen bonds. Atoms N17 and C13 in the molecule at (x, y, z) both act as hydrogen-bond donors to the pyridyl atom N11 in the molecule at (1 − x, −1/2 + y, 1/2 − z), so forming a C(4)C(7)[R21(7)] chain of rings running parallel to the [010] direction and generated by the 21 screw axis along (1/2, y, 1/4) (Fig. 5). In addition, atom C12 in the molecule at (x, y, z) acts as hydrogen-bond donor to atom O1 in the molecule at (x, 3/2 − y, −1/2 + z), so forming C(6) chain running parallel to the [001] direction and generated by the c-glide plane at y = 3/4 (Fig. 6). The combination of the [010] and [001] chains then generates a sheet parallel to (100) containing alternating R44(14) and R44(26) rings, where each type of ring is centrosymmetric (Fig. 7). There are no direction-specific interactions between adjacent sheets.