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The title compound, C
18H
12N
4O·H
2O, adopts the keto tautomeric form and the azomethine C=N double bond is in the
E configuration. The dihedral angle between the planes of the diazafluorene moiety and the phenyl ring is 11.3 (1)°. In the solid state, the molecules form infinite chain-like structures
via O-H
N hydrogen bonds involving the water molecules and diazafluorene moieties.
Supporting information
CCDC reference: 150353
The synthesis of the compound was carried out by reaction of 4,5-diazafluren-9-one and benzoylhydrazine in ethanol solution under reflux for 5 h. Single crystals were obtained by recrystallization from ethanol.
Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 1990).
4,5-Diaza-9-fluorenone Benzoylhydrazone Monohydrate
top
Crystal data top
C18H12N4O·H2O | F(000) = 664 |
Mr = 318.33 | Dx = 1.375 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
a = 8.4880 (2) Å | Cell parameters from 3585 reflections |
b = 22.7523 (2) Å | θ = 1.8–28.3° |
c = 8.7810 (2) Å | µ = 0.09 mm−1 |
β = 114.929 (1)° | T = 293 K |
V = 1537.80 (5) Å3 | Needle, yellow |
Z = 4 | 0.38 × 0.18 × 0.12 mm |
Data collection top
Siemens SMART CCD area detector diffractometer | 1870 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.078 |
Graphite monochromator | θmax = 28.3°, θmin = 1.8° |
Detector resolution: 8.33 pixels mm-1 | h = −9→11 |
ω scans | k = −29→27 |
10723 measured reflections | l = −11→11 |
3729 independent reflections | |
Refinement top
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)] = 0.061 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.121 | w = 1/[σ2(Fo2) + (0.0695P)2] where P = (Fo2 + 2Fc2)/3 |
S = 0.93 | (Δ/σ)max < 0.001 |
3729 reflections | Δρmax = 0.29 e Å−3 |
226 parameters | Δρmin = −0.28 e Å−3 |
0 restraints | Extinction correction: SHELXTL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.014 (2) |
Crystal data top
C18H12N4O·H2O | V = 1537.80 (5) Å3 |
Mr = 318.33 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 8.4880 (2) Å | µ = 0.09 mm−1 |
b = 22.7523 (2) Å | T = 293 K |
c = 8.7810 (2) Å | 0.38 × 0.18 × 0.12 mm |
β = 114.929 (1)° | |
Data collection top
Siemens SMART CCD area detector diffractometer | 1870 reflections with I > 2σ(I) |
10723 measured reflections | Rint = 0.078 |
3729 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.061 | 0 restraints |
wR(F2) = 0.121 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.93 | Δρmax = 0.29 e Å−3 |
3729 reflections | Δρmin = −0.28 e Å−3 |
226 parameters | |
Special details top
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. The data collection covered over a hemisphere of reciprocal space by a combination of three sets of exposures; each set had a different ϕ angle (0, 88 and 180°) for the crystal and each exposure of 10 s covered 0.3° in ω. The crystal-to-detector distance was 4 cm and the detector swing angle was −35°. Coverage of the unique set is over 99% complete. Crystal decay was monitored by repeating fifty initial frames at the end of data collection and analysing the duplicate reflections, and was found to be negligible. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
N1 | 1.2290 (2) | 0.57696 (9) | −0.1370 (2) | 0.0388 (5) | |
N2 | 1.2709 (2) | 0.52004 (8) | 0.1917 (2) | 0.0379 (5) | |
N3 | 0.7533 (2) | 0.64431 (9) | −0.0334 (2) | 0.0394 (5) | |
N4 | 0.6726 (2) | 0.64123 (9) | 0.0728 (3) | 0.0422 (5) | |
H4A | 0.7005 | 0.6151 | 0.1506 | 0.051* | |
O1 | 0.5059 (2) | 0.71954 (9) | −0.0606 (2) | 0.0633 (6) | |
C1 | 1.1873 (3) | 0.61027 (11) | −0.2742 (3) | 0.0474 (7) | |
H1A | 1.2598 | 0.6086 | −0.3293 | 0.057* | |
C2 | 1.0443 (4) | 0.64703 (12) | −0.3401 (3) | 0.0511 (7) | |
H2A | 1.0233 | 0.6691 | −0.4359 | 0.061* | |
C3 | 0.9327 (3) | 0.65059 (11) | −0.2620 (3) | 0.0444 (6) | |
H3A | 0.8347 | 0.6745 | −0.3039 | 0.053* | |
C4 | 0.9730 (3) | 0.61730 (10) | −0.1199 (3) | 0.0339 (5) | |
C5 | 0.8896 (3) | 0.61279 (10) | −0.0029 (3) | 0.0343 (5) | |
C6 | 1.0022 (3) | 0.57315 (10) | 0.1337 (3) | 0.0318 (5) | |
C7 | 1.0036 (3) | 0.55506 (11) | 0.2851 (3) | 0.0406 (6) | |
H7A | 0.9170 | 0.5665 | 0.3174 | 0.049* | |
C8 | 1.1394 (3) | 0.51917 (11) | 0.3863 (3) | 0.0445 (6) | |
H8A | 1.1458 | 0.5065 | 0.4895 | 0.053* | |
C9 | 1.2649 (3) | 0.50218 (11) | 0.3345 (3) | 0.0434 (6) | |
H9A | 1.3512 | 0.4766 | 0.4032 | 0.052* | |
C10 | 1.1398 (3) | 0.55455 (10) | 0.0955 (3) | 0.0306 (5) | |
C11 | 1.1208 (3) | 0.58223 (10) | −0.0623 (3) | 0.0328 (5) | |
C12 | 0.5447 (3) | 0.68221 (11) | 0.0484 (3) | 0.0420 (6) | |
C13 | 0.4626 (3) | 0.68010 (10) | 0.1692 (3) | 0.0416 (6) | |
C14 | 0.3023 (3) | 0.70743 (11) | 0.1213 (4) | 0.0505 (7) | |
H14A | 0.2461 | 0.7235 | 0.0143 | 0.061* | |
C15 | 0.2264 (4) | 0.71070 (12) | 0.2336 (4) | 0.0612 (8) | |
H15A | 0.1180 | 0.7283 | 0.2007 | 0.073* | |
C16 | 0.3093 (4) | 0.68845 (13) | 0.3912 (5) | 0.0650 (8) | |
H16A | 0.2591 | 0.6922 | 0.4665 | 0.078* | |
C17 | 0.4663 (4) | 0.66050 (13) | 0.4403 (4) | 0.0638 (8) | |
H17A | 0.5206 | 0.6443 | 0.5473 | 0.077* | |
C18 | 0.5440 (3) | 0.65644 (12) | 0.3289 (4) | 0.0529 (7) | |
H18A | 0.6508 | 0.6378 | 0.3620 | 0.063* | |
O1W | 0.6154 (2) | 0.52798 (9) | 0.1980 (2) | 0.0484 (5) | |
H1W1 | 0.636 (4) | 0.4933 (15) | 0.152 (4) | 0.089 (11)* | |
H2W1 | 0.502 (5) | 0.5253 (15) | 0.173 (5) | 0.113 (14)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
N1 | 0.0433 (12) | 0.0411 (12) | 0.0456 (12) | 0.0036 (9) | 0.0320 (10) | 0.0005 (10) |
N2 | 0.0332 (11) | 0.0428 (12) | 0.0416 (11) | 0.0027 (8) | 0.0197 (9) | 0.0055 (10) |
N3 | 0.0401 (11) | 0.0409 (12) | 0.0502 (12) | 0.0060 (9) | 0.0317 (10) | 0.0010 (9) |
N4 | 0.0427 (12) | 0.0445 (13) | 0.0538 (13) | 0.0100 (9) | 0.0342 (11) | 0.0072 (10) |
O1 | 0.0689 (13) | 0.0576 (13) | 0.0865 (14) | 0.0240 (10) | 0.0553 (11) | 0.0231 (11) |
C1 | 0.0580 (17) | 0.0518 (17) | 0.0535 (16) | 0.0043 (13) | 0.0440 (14) | 0.0063 (14) |
C2 | 0.0686 (18) | 0.0507 (17) | 0.0481 (15) | 0.0073 (13) | 0.0384 (14) | 0.0121 (13) |
C3 | 0.0531 (15) | 0.0413 (15) | 0.0479 (15) | 0.0120 (11) | 0.0301 (13) | 0.0091 (12) |
C4 | 0.0375 (13) | 0.0341 (13) | 0.0386 (13) | 0.0032 (10) | 0.0245 (11) | 0.0004 (11) |
C5 | 0.0355 (13) | 0.0349 (13) | 0.0404 (13) | 0.0000 (10) | 0.0237 (11) | −0.0005 (11) |
C6 | 0.0327 (12) | 0.0327 (13) | 0.0365 (12) | −0.0012 (9) | 0.0209 (10) | −0.0020 (10) |
C7 | 0.0383 (13) | 0.0521 (16) | 0.0412 (14) | −0.0023 (11) | 0.0264 (12) | 0.0011 (12) |
C8 | 0.0433 (15) | 0.0568 (17) | 0.0360 (13) | −0.0072 (12) | 0.0193 (12) | 0.0054 (12) |
C9 | 0.0369 (13) | 0.0486 (16) | 0.0434 (14) | 0.0028 (11) | 0.0157 (12) | 0.0110 (12) |
C10 | 0.0311 (12) | 0.0315 (12) | 0.0332 (12) | −0.0007 (9) | 0.0175 (10) | −0.0022 (10) |
C11 | 0.0363 (13) | 0.0324 (13) | 0.0391 (13) | −0.0006 (10) | 0.0252 (11) | −0.0022 (10) |
C12 | 0.0416 (14) | 0.0366 (15) | 0.0598 (17) | 0.0030 (11) | 0.0332 (13) | −0.0007 (13) |
C13 | 0.0378 (13) | 0.0358 (14) | 0.0632 (17) | −0.0030 (10) | 0.0331 (13) | −0.0100 (12) |
C14 | 0.0474 (15) | 0.0357 (15) | 0.083 (2) | 0.0016 (11) | 0.0422 (15) | −0.0045 (13) |
C15 | 0.0539 (17) | 0.0458 (17) | 0.111 (3) | 0.0034 (13) | 0.0617 (19) | −0.0010 (18) |
C16 | 0.076 (2) | 0.0556 (19) | 0.098 (2) | −0.0038 (16) | 0.070 (2) | −0.0063 (18) |
C17 | 0.072 (2) | 0.071 (2) | 0.070 (2) | 0.0039 (16) | 0.0511 (18) | 0.0004 (16) |
C18 | 0.0453 (15) | 0.0640 (19) | 0.0588 (17) | 0.0076 (13) | 0.0312 (14) | −0.0038 (15) |
O1W | 0.0393 (11) | 0.0476 (12) | 0.0678 (13) | 0.0062 (8) | 0.0318 (10) | 0.0010 (10) |
Geometric parameters (Å, º) top
N1—C1 | 1.339 (3) | C7—C8 | 1.386 (3) |
N1—C11 | 1.340 (3) | C7—H7A | 0.9300 |
N2—C10 | 1.332 (3) | C8—C9 | 1.379 (3) |
N2—C9 | 1.339 (3) | C8—H8A | 0.9300 |
N3—C5 | 1.290 (3) | C9—H9A | 0.9300 |
N3—N4 | 1.371 (3) | C10—C11 | 1.467 (3) |
N4—C12 | 1.378 (3) | C12—C13 | 1.496 (3) |
N4—H4A | 0.8600 | C13—C18 | 1.384 (4) |
O1—C12 | 1.216 (3) | C13—C14 | 1.390 (3) |
C1—C2 | 1.384 (4) | C14—C15 | 1.390 (4) |
C1—H1A | 0.9300 | C14—H14A | 0.9300 |
C2—C3 | 1.387 (3) | C15—C16 | 1.358 (4) |
C2—H2A | 0.9300 | C15—H15A | 0.9300 |
C3—C4 | 1.374 (3) | C16—C17 | 1.372 (4) |
C3—H3A | 0.9300 | C16—H16A | 0.9300 |
C4—C11 | 1.390 (3) | C17—C18 | 1.394 (4) |
C4—C5 | 1.476 (3) | C17—H17A | 0.9300 |
C5—C6 | 1.483 (3) | C18—H18A | 0.9300 |
C6—C7 | 1.387 (3) | O1W—H1W1 | 0.94 (4) |
C6—C10 | 1.410 (3) | O1W—H2W1 | 0.90 (4) |
| | | |
C1—N1—C11 | 114.5 (2) | N2—C9—H9A | 117.9 |
C10—N2—C9 | 114.97 (19) | C8—C9—H9A | 117.9 |
C5—N3—N4 | 119.4 (2) | N2—C10—C6 | 125.4 (2) |
N3—N4—C12 | 116.5 (2) | N2—C10—C11 | 125.61 (19) |
N3—N4—H4A | 121.8 | C6—C10—C11 | 108.87 (19) |
C12—N4—H4A | 121.8 | N1—C11—C4 | 125.0 (2) |
N1—C1—C2 | 124.8 (2) | N1—C11—C10 | 126.7 (2) |
N1—C1—H1A | 117.6 | C4—C11—C10 | 108.27 (18) |
C2—C1—H1A | 117.6 | O1—C12—N4 | 122.0 (2) |
C1—C2—C3 | 119.3 (2) | O1—C12—C13 | 121.8 (2) |
C1—C2—H2A | 120.3 | N4—C12—C13 | 116.1 (2) |
C3—C2—H2A | 120.3 | C18—C13—C14 | 119.2 (2) |
C4—C3—C2 | 117.2 (2) | C18—C13—C12 | 123.3 (2) |
C4—C3—H3A | 121.4 | C14—C13—C12 | 117.4 (2) |
C2—C3—H3A | 121.4 | C15—C14—C13 | 119.8 (3) |
C3—C4—C11 | 119.2 (2) | C15—C14—H14A | 120.1 |
C3—C4—C5 | 131.4 (2) | C13—C14—H14A | 120.1 |
C11—C4—C5 | 109.31 (19) | C16—C15—C14 | 120.5 (3) |
N3—C5—C4 | 117.9 (2) | C16—C15—H15A | 119.8 |
N3—C5—C6 | 136.2 (2) | C14—C15—H15A | 119.8 |
C4—C5—C6 | 105.69 (18) | C15—C16—C17 | 120.7 (3) |
C7—C6—C10 | 117.8 (2) | C15—C16—H16A | 119.6 |
C7—C6—C5 | 134.2 (2) | C17—C16—H16A | 119.6 |
C10—C6—C5 | 107.83 (19) | C16—C17—C18 | 119.6 (3) |
C8—C7—C6 | 117.2 (2) | C16—C17—H17A | 120.2 |
C8—C7—H7A | 121.4 | C18—C17—H17A | 120.2 |
C6—C7—H7A | 121.4 | C13—C18—C17 | 120.2 (2) |
C9—C8—C7 | 120.2 (2) | C13—C18—H18A | 119.9 |
C9—C8—H8A | 119.9 | C17—C18—H18A | 119.9 |
C7—C8—H8A | 119.9 | H1W1—O1W—H2W1 | 102 (3) |
N2—C9—C8 | 124.3 (2) | | |
| | | |
C5—N3—N4—C12 | 170.4 (2) | C5—C6—C10—C11 | 1.0 (2) |
C11—N1—C1—C2 | −1.0 (4) | C1—N1—C11—C4 | 1.9 (3) |
N1—C1—C2—C3 | −0.2 (4) | C1—N1—C11—C10 | −175.5 (2) |
C1—C2—C3—C4 | 0.8 (4) | C3—C4—C11—N1 | −1.4 (4) |
C2—C3—C4—C11 | −0.1 (4) | C5—C4—C11—N1 | −178.7 (2) |
C2—C3—C4—C5 | 176.6 (2) | C3—C4—C11—C10 | 176.4 (2) |
N4—N3—C5—C4 | −179.95 (19) | C5—C4—C11—C10 | −0.9 (3) |
N4—N3—C5—C6 | −5.5 (4) | N2—C10—C11—N1 | 1.0 (4) |
C3—C4—C5—N3 | 0.6 (4) | C6—C10—C11—N1 | 177.6 (2) |
C11—C4—C5—N3 | 177.5 (2) | N2—C10—C11—C4 | −176.7 (2) |
C3—C4—C5—C6 | −175.4 (2) | C6—C10—C11—C4 | −0.1 (3) |
C11—C4—C5—C6 | 1.5 (3) | N3—N4—C12—O1 | −0.6 (3) |
N3—C5—C6—C7 | −0.7 (5) | N3—N4—C12—C13 | −177.6 (2) |
C4—C5—C6—C7 | 174.2 (2) | O1—C12—C13—C18 | −153.0 (3) |
N3—C5—C6—C10 | −176.4 (3) | N4—C12—C13—C18 | 24.0 (4) |
C4—C5—C6—C10 | −1.5 (2) | O1—C12—C13—C14 | 22.0 (4) |
C10—C6—C7—C8 | −1.0 (3) | N4—C12—C13—C14 | −161.0 (2) |
C5—C6—C7—C8 | −176.4 (2) | C18—C13—C14—C15 | 0.1 (4) |
C6—C7—C8—C9 | −0.8 (4) | C12—C13—C14—C15 | −175.1 (2) |
C10—N2—C9—C8 | −2.7 (3) | C13—C14—C15—C16 | 1.4 (4) |
C7—C8—C9—N2 | 2.9 (4) | C14—C15—C16—C17 | −2.4 (4) |
C9—N2—C10—C6 | 0.7 (3) | C15—C16—C17—C18 | 1.9 (5) |
C9—N2—C10—C11 | 176.8 (2) | C14—C13—C18—C17 | −0.5 (4) |
C7—C6—C10—N2 | 1.1 (3) | C12—C13—C18—C17 | 174.4 (3) |
C5—C6—C10—N2 | 177.6 (2) | C16—C17—C18—C13 | −0.5 (4) |
C7—C6—C10—C11 | −175.5 (2) | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N4—H4A···O1W | 0.86 | 2.21 | 2.921 (3) | 140 |
O1W—H1W1···N1i | 0.94 (3) | 2.00 (4) | 2.886 (3) | 157 (3) |
O1W—H2W1···N2ii | 0.89 (5) | 2.04 (5) | 2.907 (3) | 163 (4) |
Symmetry codes: (i) −x+2, −y+1, −z; (ii) x−1, y, z. |
Experimental details
Crystal data |
Chemical formula | C18H12N4O·H2O |
Mr | 318.33 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 293 |
a, b, c (Å) | 8.4880 (2), 22.7523 (2), 8.7810 (2) |
β (°) | 114.929 (1) |
V (Å3) | 1537.80 (5) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.38 × 0.18 × 0.12 |
|
Data collection |
Diffractometer | Siemens SMART CCD area detector diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 10723, 3729, 1870 |
Rint | 0.078 |
(sin θ/λ)max (Å−1) | 0.667 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.061, 0.121, 0.93 |
No. of reflections | 3729 |
No. of parameters | 226 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.29, −0.28 |
Selected geometric parameters (Å, º) topN1—C1 | 1.339 (3) | N3—C5 | 1.290 (3) |
N1—C11 | 1.340 (3) | N3—N4 | 1.371 (3) |
N2—C10 | 1.332 (3) | N4—C12 | 1.378 (3) |
N2—C9 | 1.339 (3) | O1—C12 | 1.216 (3) |
| | | |
C5—N3—N4 | 119.4 (2) | O1—C12—C13 | 121.8 (2) |
N3—N4—C12 | 116.5 (2) | N4—C12—C13 | 116.1 (2) |
O1—C12—N4 | 122.0 (2) | | |
| | | |
C5—N3—N4—C12 | 170.4 (2) | N3—N4—C12—C13 | −177.6 (2) |
N3—N4—C12—O1 | −0.6 (3) | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N4—H4A···O1W | 0.86 | 2.21 | 2.921 (3) | 140 |
O1W—H1W1···N1i | 0.94 (3) | 2.00 (4) | 2.886 (3) | 157 (3) |
O1W—H2W1···N2ii | 0.89 (5) | 2.04 (5) | 2.907 (3) | 163 (4) |
Symmetry codes: (i) −x+2, −y+1, −z; (ii) x−1, y, z. |
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Aroylhydrazones have continued to attract extensive attention of chemists because of their wide biological activities and their strong abilities to chelate to transition metal ions, lanthanide metal ions and main group metal ions forming metal complexes (Fun et al., 1999; Lu et al., 1999; Sangeetha et al., 1996; Ainscough et al., 1998). On the other hand, 4,5-diazafluoren-9-one and its derivatives are also strong chelating agents and has been used as ligands to form functional ruthenium complexes (Chao et al., 1999). The combination of the two functional group yielding ligands capable of forming polymetallic complexes would therefore be of interest for their potential multi-redox, catalytic, electronic and energy transfer properties. As part of studies on the synthesis and characterization of new aroylhydrazone derivatives, we report here the crystal structure of 4,5-diaza-9-fluorenone benzoylhydrazone monohydrate, (I). \sch
The bond lengths and angles observed in this structure are normal and comparable to those found in the structures of other benzoylhydrazine (Fun et al., 1997) and 4,5-diazafluorene derivatives (Lu et al., 1996). The molecule is in keto tautomeric form. The dihedral angles between the diazafluorene moiety and the phenyl ring is 11.3 (1)°, and the two fragments make 13.2 (1) and 23.2 (1)°, respectively, with the cetral hydrazone moiety. In the solid state, the molecules form infinite chain-like structures via O—H···N hydrogen bonds involving the water molecules and diazafluorene moieties.
We have observed previously that due to the possibility of different charge concentrations between the two pyridinyl N atoms of the diazaflurene moiety, the one with greater charge is involved in the stronger hydrogen bonds, whereas the other may be involved in only a weak interaction (Fun et al., 1995; Lu et al., 1995). But in this structure, both the N atoms are involved in a similar type of O—H···N hydrogen bond with the water molecule. We also note that the aroylhydrazine derivatives crystallize in hydrated forms only.