Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536805030783/wn6384sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536805030783/wn6384Isup2.hkl |
CCDC reference: 287751
Key indicators
- Single-crystal X-ray study
- T = 273 K
- Mean (C-C) = 0.002 Å
- R factor = 0.030
- wR factor = 0.088
- Data-to-parameter ratio = 31.2
checkCIF/PLATON results
No syntax errors found
Alert level C ABSTM02_ALERT_3_C The ratio of expected to reported Tmax/Tmin(RR) is > 1.10 Tmin and Tmax reported: 0.324 0.640 Tmin and Tmax expected: 0.248 0.612 RR = 1.252 Please check that your absorption correction is appropriate. PLAT060_ALERT_3_C Ratio Tmax/Tmin (Exp-to-Rep) (too) Large ....... 1.22 PLAT062_ALERT_4_C Rescale T(min) & T(max) by ..................... 0.96 PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density .... 2.72 PLAT731_ALERT_1_C Bond Calc 0.89(2), Rep 0.893(9) ...... 2.22 su-Rat N1 -H1A 1.555 1.555
Alert level G REFLT03_ALERT_1_G ALERT: Expected hkl max differ from CIF values From the CIF: _diffrn_reflns_theta_max 38.16 From the CIF: _reflns_number_total 5338 From the CIF: _diffrn_reflns_limit_ max hkl 13. 8. 27. From the CIF: _diffrn_reflns_limit_ min hkl -13. -7. -27. TEST1: Expected hkl limits for theta max Calculated maximum hkl 13. 8. 29. Calculated minimum hkl -13. -8. -29. REFLT03_ALERT_4_G WARNING: Large fraction of Friedel related reflns may be needed to determine absolute structure From the CIF: _diffrn_reflns_theta_max 38.16 From the CIF: _reflns_number_total 5338 Count of symmetry unique reflns 3762 Completeness (_total/calc) 141.89% TEST3: Check Friedels for noncentro structure Estimate of Friedel pairs measured 1576 Fraction of Friedel pairs measured 0.419 Are heavy atom types Z>Si present yes
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 5 ALERT level C = Check and explain 2 ALERT level G = General alerts; check 2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 1 ALERT type 2 Indicator that the structure model may be wrong or deficient 2 ALERT type 3 Indicator that the structure quality may be low 2 ALERT type 4 Improvement, methodology, query or suggestion
checkCIF publication errors
Alert level A PUBL023_ALERT_1_A There is a mismatched ^ on line 379 Refinement of F2^ against ALL reflections. The weighted R-factor wR and If you require a ^ then it should be escaped with a \, i.e. \^ Otherwise there must be a matching closing ~, e.g. ^12^C PUBL023_ALERT_1_A There is a mismatched ^ on line 380 goodness of fit S are based on F2^, conventional R-factors R are based If you require a ^ then it should be escaped with a \, i.e. \^ Otherwise there must be a matching closing ~, e.g. ^12^C PUBL023_ALERT_1_A There is a mismatched ^ on line 381 on F, with F set to zero for negative F2^. The threshold expression of If you require a ^ then it should be escaped with a \, i.e. \^ Otherwise there must be a matching closing ~, e.g. ^12^C PUBL023_ALERT_1_A There is a mismatched ^ on line 384 on F2^ are statistically about twice as large as those based on F, and R- If you require a ^ then it should be escaped with a \, i.e. \^ Otherwise there must be a matching closing ~, e.g. ^12^C
4 ALERT level A = Data missing that is essential or data in wrong format 0 ALERT level G = General alerts. Data that may be required is missing
Compound (I) was obtained by the Claisen–Schmidt condensation of 4-aminoacetophenone (5.4 g, 0.04 mol) and 3-bromobenzaldehyde (7.4 g, 0.04 mol) in a 20% solution of NaOH and ethanol at 273 K over a period of 24 h. The product was isolated by neutralizing the reaction mixture with dilute hydrochloric acid. The crude product was recrystallized from ethanol.
Amino H atoms were located in a difference Fourier map and both positional and isotropic displacement parameters were refined, with an N—H distance restraint of 0.90 (1) Å. The C-bound H atoms were placed in calculated positions and constrained to ride on their parent atoms, with C—H = 0.93 Å and Uiso(H) = 1.2Ueq(C). The highest residual electron-density peak is located 0.76 Å from atom Br1.
Data collection: APEX2 (Bruker, 2005); cell refinement: APEX2; data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 1998); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003).
C15H12BrNO | F(000) = 304 |
Mr = 302.17 | Dx = 1.594 Mg m−3 |
Monoclinic, P21 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2yb | Cell parameters from 6184 reflections |
a = 8.0012 (2) Å | θ = 2.6–37.8° |
b = 4.6257 (1) Å | µ = 3.25 mm−1 |
c = 17.1148 (5) Å | T = 273 K |
β = 96.413 (1)° | Block, colourless |
V = 629.47 (3) Å3 | 0.45 × 0.40 × 0.15 mm |
Z = 2 |
Bruker SMART APEX2 CCD area-detector diffractometer | 5338 independent reflections |
Radiation source: fine-focus sealed tube | 4831 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.023 |
Detector resolution: 8.33 pixels mm-1 | θmax = 38.2°, θmin = 1.2° |
ω scans | h = −13→13 |
Absorption correction: multi-scan (SADABS; Bruker, 2005) | k = −7→8 |
Tmin = 0.324, Tmax = 0.640 | l = −27→27 |
9718 measured reflections |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.030 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.088 | w = 1/[σ2(Fo2) + (0.0546P)2] where P = (Fo2 + 2Fc2)/3 |
S = 1.09 | (Δ/σ)max = 0.001 |
5338 reflections | Δρmax = 1.36 e Å−3 |
171 parameters | Δρmin = −0.50 e Å−3 |
3 restraints | Absolute structure: Flack (1983), 1968 Friedel pairs |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: 0.008 (6) |
C15H12BrNO | V = 629.47 (3) Å3 |
Mr = 302.17 | Z = 2 |
Monoclinic, P21 | Mo Kα radiation |
a = 8.0012 (2) Å | µ = 3.25 mm−1 |
b = 4.6257 (1) Å | T = 273 K |
c = 17.1148 (5) Å | 0.45 × 0.40 × 0.15 mm |
β = 96.413 (1)° |
Bruker SMART APEX2 CCD area-detector diffractometer | 5338 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2005) | 4831 reflections with I > 2σ(I) |
Tmin = 0.324, Tmax = 0.640 | Rint = 0.023 |
9718 measured reflections |
R[F2 > 2σ(F2)] = 0.030 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.088 | Δρmax = 1.36 e Å−3 |
S = 1.09 | Δρmin = −0.50 e Å−3 |
5338 reflections | Absolute structure: Flack (1983), 1968 Friedel pairs |
171 parameters | Absolute structure parameter: 0.008 (6) |
3 restraints |
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. |
x | y | z | Uiso*/Ueq | ||
Br1 | −0.101835 (19) | −0.32301 (7) | 0.403165 (9) | 0.02839 (5) | |
O1 | 0.28559 (15) | 0.7796 (3) | 0.13955 (8) | 0.0241 (2) | |
N1 | 1.01570 (17) | 1.1488 (4) | 0.06315 (9) | 0.0226 (3) | |
H1A | 1.108 (2) | 1.089 (8) | 0.0931 (12) | 0.036 (10)* | |
H1B | 1.010 (3) | 1.323 (3) | 0.0412 (14) | 0.030 (7)* | |
C1 | 0.12750 (19) | 0.0295 (4) | 0.32979 (10) | 0.0196 (3) | |
H1 | 0.0317 | 0.0941 | 0.2990 | 0.024* | |
C2 | 0.1135 (2) | −0.1747 (4) | 0.38803 (10) | 0.0210 (3) | |
C3 | 0.2535 (2) | −0.2749 (4) | 0.43574 (10) | 0.0243 (4) | |
H3 | 0.2425 | −0.4107 | 0.4749 | 0.029* | |
C4 | 0.4106 (2) | −0.1665 (4) | 0.42336 (11) | 0.0234 (3) | |
H4 | 0.5057 | −0.2316 | 0.4547 | 0.028* | |
C5 | 0.4282 (2) | 0.0370 (4) | 0.36519 (10) | 0.0213 (3) | |
H5 | 0.5344 | 0.1063 | 0.3578 | 0.026* | |
C6 | 0.28545 (18) | 0.1388 (3) | 0.31727 (9) | 0.0181 (3) | |
C7 | 0.2948 (2) | 0.3528 (4) | 0.25505 (10) | 0.0190 (3) | |
H7 | 0.1938 | 0.4031 | 0.2259 | 0.023* | |
C8 | 0.4334 (2) | 0.4839 (4) | 0.23566 (10) | 0.0203 (3) | |
H8 | 0.5372 | 0.4376 | 0.2628 | 0.024* | |
C9 | 0.42462 (17) | 0.7008 (5) | 0.17196 (9) | 0.0183 (3) | |
C10 | 0.58089 (19) | 0.8209 (4) | 0.14734 (9) | 0.0175 (3) | |
C11 | 0.74161 (18) | 0.7208 (4) | 0.17693 (10) | 0.0210 (3) | |
H11 | 0.7514 | 0.5784 | 0.2155 | 0.025* | |
C12 | 0.88468 (19) | 0.8295 (4) | 0.14996 (10) | 0.0204 (3) | |
H12 | 0.9893 | 0.7585 | 0.1703 | 0.024* | |
C13 | 0.87471 (19) | 1.0464 (4) | 0.09210 (9) | 0.0180 (3) | |
C14 | 0.71372 (18) | 1.1462 (4) | 0.06155 (9) | 0.0199 (3) | |
H14 | 0.7037 | 1.2868 | 0.0225 | 0.024* | |
C15 | 0.57144 (19) | 1.0367 (4) | 0.08926 (9) | 0.0190 (3) | |
H15 | 0.4666 | 1.1073 | 0.0690 | 0.023* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Br1 | 0.02547 (7) | 0.02900 (9) | 0.03259 (9) | −0.00492 (8) | 0.01165 (5) | 0.00037 (9) |
O1 | 0.0150 (4) | 0.0279 (6) | 0.0295 (6) | 0.0018 (4) | 0.0021 (4) | 0.0067 (5) |
N1 | 0.0178 (4) | 0.0220 (8) | 0.0284 (6) | 0.0003 (5) | 0.0050 (4) | 0.0048 (6) |
C1 | 0.0187 (6) | 0.0179 (6) | 0.0226 (7) | 0.0000 (5) | 0.0039 (5) | −0.0013 (5) |
C2 | 0.0222 (6) | 0.0195 (7) | 0.0224 (7) | −0.0020 (6) | 0.0070 (5) | −0.0014 (5) |
C3 | 0.0276 (7) | 0.0259 (11) | 0.0198 (7) | −0.0009 (6) | 0.0049 (5) | 0.0018 (5) |
C4 | 0.0246 (7) | 0.0237 (8) | 0.0212 (7) | −0.0005 (6) | 0.0000 (5) | 0.0024 (6) |
C5 | 0.0211 (6) | 0.0195 (7) | 0.0231 (8) | −0.0007 (5) | 0.0011 (5) | 0.0009 (5) |
C6 | 0.0192 (5) | 0.0140 (8) | 0.0214 (6) | 0.0000 (5) | 0.0034 (4) | −0.0003 (5) |
C7 | 0.0186 (6) | 0.0167 (6) | 0.0218 (7) | 0.0004 (5) | 0.0031 (5) | 0.0003 (5) |
C8 | 0.0176 (6) | 0.0203 (7) | 0.0232 (7) | 0.0007 (5) | 0.0029 (5) | 0.0019 (5) |
C9 | 0.0159 (4) | 0.0181 (7) | 0.0209 (6) | 0.0006 (6) | 0.0025 (4) | 0.0008 (6) |
C10 | 0.0157 (5) | 0.0182 (6) | 0.0186 (7) | 0.0004 (5) | 0.0022 (4) | 0.0004 (5) |
C11 | 0.0168 (5) | 0.0235 (10) | 0.0227 (7) | 0.0026 (5) | 0.0020 (4) | 0.0046 (5) |
C12 | 0.0148 (5) | 0.0224 (7) | 0.0239 (7) | 0.0031 (5) | 0.0017 (5) | 0.0040 (5) |
C13 | 0.0169 (5) | 0.0171 (6) | 0.0199 (7) | 0.0004 (5) | 0.0022 (4) | −0.0008 (5) |
C14 | 0.0179 (5) | 0.0188 (8) | 0.0229 (6) | 0.0012 (5) | 0.0016 (4) | 0.0039 (5) |
C15 | 0.0164 (5) | 0.0197 (7) | 0.0206 (7) | 0.0018 (5) | 0.0007 (5) | 0.0018 (5) |
Br1—C2 | 1.8987 (17) | C7—C8 | 1.338 (2) |
O1—C9 | 1.2410 (17) | C7—H7 | 0.93 |
N1—C13 | 1.367 (2) | C8—C9 | 1.477 (3) |
N1—H1A | 0.893 (9) | C8—H8 | 0.93 |
N1—H1B | 0.889 (10) | C9—C10 | 1.472 (2) |
C1—C2 | 1.387 (2) | C10—C15 | 1.405 (2) |
C1—C6 | 1.400 (2) | C10—C11 | 1.407 (2) |
C1—H1 | 0.93 | C11—C12 | 1.376 (2) |
C2—C3 | 1.390 (2) | C11—H11 | 0.93 |
C3—C4 | 1.391 (3) | C12—C13 | 1.406 (2) |
C3—H3 | 0.93 | C12—H12 | 0.93 |
C4—C5 | 1.389 (3) | C13—C14 | 1.413 (2) |
C4—H4 | 0.93 | C14—C15 | 1.378 (2) |
C5—C6 | 1.411 (2) | C14—H14 | 0.93 |
C5—H5 | 0.93 | C15—H15 | 0.93 |
C6—C7 | 1.462 (2) | ||
C13—N1—H1A | 110.3 (19) | C7—C8—C9 | 121.21 (14) |
C13—N1—H1B | 117.4 (19) | C7—C8—H8 | 119.4 |
H1A—N1—H1B | 122 (3) | C9—C8—H8 | 119.4 |
C2—C1—C6 | 120.19 (15) | O1—C9—C10 | 120.59 (17) |
C2—C1—H1 | 119.9 | O1—C9—C8 | 119.71 (15) |
C6—C1—H1 | 119.9 | C10—C9—C8 | 119.70 (12) |
C1—C2—C3 | 121.63 (16) | C15—C10—C11 | 117.61 (15) |
C1—C2—Br1 | 119.45 (13) | C15—C10—C9 | 119.36 (14) |
C3—C2—Br1 | 118.91 (14) | C11—C10—C9 | 122.97 (15) |
C2—C3—C4 | 118.24 (17) | C12—C11—C10 | 121.35 (15) |
C2—C3—H3 | 120.9 | C12—C11—H11 | 119.3 |
C4—C3—H3 | 120.9 | C10—C11—H11 | 119.3 |
C5—C4—C3 | 121.27 (16) | C11—C12—C13 | 120.86 (14) |
C5—C4—H4 | 119.4 | C11—C12—H12 | 119.6 |
C3—C4—H4 | 119.4 | C13—C12—H12 | 119.6 |
C4—C5—C6 | 120.18 (16) | N1—C13—C12 | 121.24 (14) |
C4—C5—H5 | 119.9 | N1—C13—C14 | 120.53 (15) |
C6—C5—H5 | 119.9 | C12—C13—C14 | 118.15 (15) |
C1—C6—C5 | 118.48 (15) | C15—C14—C13 | 120.46 (16) |
C1—C6—C7 | 118.44 (13) | C15—C14—H14 | 119.8 |
C5—C6—C7 | 123.07 (14) | C13—C14—H14 | 119.8 |
C8—C7—C6 | 126.76 (14) | C14—C15—C10 | 121.57 (14) |
C8—C7—H7 | 116.6 | C14—C15—H15 | 119.2 |
C6—C7—H7 | 116.6 | C10—C15—H15 | 119.2 |
C6—C1—C2—C3 | 0.5 (3) | O1—C9—C10—C15 | 3.1 (3) |
C6—C1—C2—Br1 | −179.30 (13) | C8—C9—C10—C15 | −177.10 (17) |
C1—C2—C3—C4 | −0.5 (3) | O1—C9—C10—C11 | −174.06 (18) |
Br1—C2—C3—C4 | 179.30 (14) | C8—C9—C10—C11 | 5.7 (3) |
C2—C3—C4—C5 | 0.2 (3) | C15—C10—C11—C12 | −0.1 (3) |
C3—C4—C5—C6 | 0.2 (3) | C9—C10—C11—C12 | 177.07 (17) |
C2—C1—C6—C5 | −0.2 (2) | C10—C11—C12—C13 | 0.4 (3) |
C2—C1—C6—C7 | 179.75 (15) | C11—C12—C13—N1 | −177.84 (17) |
C4—C5—C6—C1 | −0.2 (3) | C11—C12—C13—C14 | −1.0 (3) |
C4—C5—C6—C7 | 179.93 (17) | N1—C13—C14—C15 | 178.15 (16) |
C1—C6—C7—C8 | 178.77 (17) | C12—C13—C14—C15 | 1.3 (3) |
C5—C6—C7—C8 | −1.3 (3) | C13—C14—C15—C10 | −1.0 (3) |
C6—C7—C8—C9 | −179.00 (17) | C11—C10—C15—C14 | 0.4 (3) |
C7—C8—C9—O1 | 5.4 (3) | C9—C10—C15—C14 | −176.88 (17) |
C7—C8—C9—C10 | −174.40 (17) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···O1i | 0.89 (2) | 2.11 (3) | 2.943 (2) | 155 (3) |
N1—H1B···N1ii | 0.89 (2) | 2.33 (2) | 3.157 (2) | 155 (2) |
C7—H7···O1 | 0.93 | 2.45 | 2.789 (2) | 102 |
C12—H12···O1i | 0.93 | 2.49 | 3.241 (2) | 138 |
Symmetry codes: (i) x+1, y, z; (ii) −x+2, y+1/2, −z. |
Experimental details
Crystal data | |
Chemical formula | C15H12BrNO |
Mr | 302.17 |
Crystal system, space group | Monoclinic, P21 |
Temperature (K) | 273 |
a, b, c (Å) | 8.0012 (2), 4.6257 (1), 17.1148 (5) |
β (°) | 96.413 (1) |
V (Å3) | 629.47 (3) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 3.25 |
Crystal size (mm) | 0.45 × 0.40 × 0.15 |
Data collection | |
Diffractometer | Bruker SMART APEX2 CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 2005) |
Tmin, Tmax | 0.324, 0.640 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 9718, 5338, 4831 |
Rint | 0.023 |
(sin θ/λ)max (Å−1) | 0.869 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.030, 0.088, 1.09 |
No. of reflections | 5338 |
No. of parameters | 171 |
No. of restraints | 3 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 1.36, −0.50 |
Absolute structure | Flack (1983), 1968 Friedel pairs |
Absolute structure parameter | 0.008 (6) |
Computer programs: APEX2 (Bruker, 2005), APEX2, SAINT (Bruker, 2005), SHELXTL (Sheldrick, 1998), SHELXTL and PLATON (Spek, 2003).
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···O1i | 0.89 (2) | 2.11 (3) | 2.943 (2) | 155 (3) |
N1—H1B···N1ii | 0.89 (2) | 2.33 (2) | 3.157 (2) | 155 (2) |
C7—H7···O1 | 0.93 | 2.45 | 2.789 (2) | 102 |
C12—H12···O1i | 0.93 | 2.49 | 3.241 (2) | 138 |
Symmetry codes: (i) x+1, y, z; (ii) −x+2, y+1/2, −z. |
Chalcones (1,3-diarylpropen-1-ones) and their heterocyclic analogues possess a number of biological attributes and some of these have been reviewed. The antibacterial, fungistatic and fungicidal properties of these compounds have been reviewed by Opletalova (2000) and Opletalova & Sedivy (1999). The cytotoxic, anticancer, chemopreventative, mutagenic, antimicrobial, antiviral, antiprotozoal and insecticidal activities and enzyme-inhibitory properties of a variety of chalcones have also been reviewed (Dimmock et al., 1999). Photo-cross-linkable polymers containing the chalcone group act as negative photo resist materials used in a wide variety of applications (Balaji et al., 2003). Chalcones are also used in designing effective second-order non-linear optical materials (Zhao et al., 2000). The structure determination of the title compound, (I), was undertaken as part of our study of chalcones.
Bond lengths and angles in (I) are comparable with those reported for related structures (Sathiya Moorthi, Chinnakali, Nanjundan, Radhika et al., 2005; Sathiya Moorthi, Chinnakali, Nanjundan, Selvam et al., 2005; Sathiya Moorthi, Chinnakali, Nanjundan, Unnithan et al., 2005) The short H5···H8 (2.24 Å) contact causes the bond angles C5—C6—C7 [123.07 (14)°] and C6—C7—C8 [126.76 (14)°] to deviate significantly from 120°. Also, the short H8···H11 (2.08 Å) contact results in a slight widening of the C9—C10—C11 angle to 122.97 (15)°. The sum of the angles around atom N1 is 349.7° and the deviation of atom N1 from the C13/H1A/H1B plane is 0.19 (2) Å, indicating its pyramidal nature.
The molecule of (I) (Fig. 1) is approximately planar. The enone fragment of the molecule containing atoms C7, C8, C9 and O1 is planar within ±0.022 (2) Å. This plane makes dihedral angles of 3.1 (1) and 7.1 (1)°, respectively, with the C1–C6 and C10–C15 benzene rings. The dihedral angle between the benzene rings is 9.6 (1)°. The H atoms attached to C7 and C8 are trans to each other.
The weak intramolecular C7—H7···O1 interaction generates an S(5) ring motif. In the crystal structure, the molecules translated by one unit cell along the a-axis direction are linked by N1—H1A···O1i and C12—H12···O1i [symmetry code: (i) 1 + x, y, z] hydrogen-bonding interactions to form a chain (Table 1). These interactions together constitute a pair of bifurcated acceptor bonds, generating an R21(6) motif (Bernstein et al., 1995). The screw-related molecules of adjacent chains are linked via N1—H1B···N1ii [symmetry code: (ii) 2 − x, 1/2 + y, −z] hydrogen bonds into a sheet-like structure parallel to the ab plane (Fig. 2).