N′-[(Z)-4-(Dimethyl­amino)benzyl­idene]-4-nitro­benzohydrazide mono­hydrate

Fun, H.-K.; Jebas, S.R.; Sujith, K.V.; Patil, P.S.; Kalluraya, B.

doi:10.1107/S1600536808028328

organic compounds

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ISSN: 2056-9890

Volume 64| Part 10| October 2008| Pages o1907-o1908

doi:10.1107/S1600536808028328

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N′-[(Z)-4-(Dimethylamino)benzylidene]-4-nitrobenzohydrazide monohydrate

Hoong-Kun Fun,^a ^* Samuel Robinson Jebas,^a ‡ K. V. Sujith,^b P. S. Patil ^c § and B. Kalluraya ^b

^aX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia, ^bDepartment of Studies in Chemistry, Mangalore University, Mangalagangotri, Mangalore 574199, India, and ^cDepartment of Physics, K. L. E. Society's K. L. E. Institute of Technology, Gokul Road, Hubli 590 030, India
^*Correspondence e-mail: hkfun@usm.my

(Received 2 September 2008; accepted 4 September 2008; online 13 September 2008)

In the asymmetric unit of the title compound, C₁₆H₁₆N₄O₃·H₂O, there are two symmetry-independent hydrazide molecules with almost identical geometries, and two independent water molecules. The dihedral angles between the two benzene rings in the two hydrazide molecules are 0.11 (5) and 0.77 (5)°. In one molecule, an intramolecular C—H⋯O hydrogen bond generates a ring of graph-set motif S(5). Intermolecular N—H⋯O, O—H⋯O, O—H⋯N and C—H⋯O hydrogen bonds and π–π stacking interactions between the benzene rings [centroid–centroid distances in the range 3.5021 (6)–3.6403 (6) Å] are observed, together with O⋯O [2.7226 (11) Å], O⋯N [2.7072 (10) Å] and N⋯O [2.7072 (10)–2.8582 (12) Å] short contacts. The hydrazine molecules are stacked along the b axis and adjacent molecules are linked by water molecules.

Related literature

For related literature on hydrazones, see: Rollas & Küçükgüzel (2007 ); Singh et al. (1992 ); Ergenç & Günay (1998 ); Durgun et al. (1993 ). For a related structure, see: Fun et al. (2008 ). For bond-length data, see: Allen et al. (1987 ). For graph-set analysis of hydrogen bonding, see: Bernstein et al. (1995 ).

Experimental

Crystal data

C₁₆H₁₆N₄O₃·H₂O
M_r = 330.34
Triclinic, $[P \overline 1]$
a = 6.5866 (2) Å
b = 7.1337 (2) Å
c = 34.4059 (12) Å
α = 92.113 (2)°
β = 90.918 (2)°
γ = 107.816 (1)°
V = 1537.42 (8) Å³
Z = 4
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 100.0 (1) K
0.41 × 0.13 × 0.10 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ) T_min = 0.959, T_max = 0.990
52996 measured reflections
11039 independent reflections
8656 reflections with I > 2σ(I)
R_int = 0.028

Refinement

R[F² > 2σ(F²)] = 0.048
wR(F²) = 0.155
S = 1.07
11039 reflections
461 parameters
8 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.45 e Å⁻³
Δρ_min = −0.36 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1A—H1NA⋯O1Wⁱ	0.850 (9)	2.024 (10)	2.8582 (11)	166.8 (16)
O2W—H2W2⋯O1Wⁱⁱ	0.839 (8)	2.066 (9)	2.8892 (12)	166.9 (16)
O2W—H1W2⋯N2Bⁱⁱⁱ	0.838 (8)	2.435 (11)	3.1989 (12)	151.8 (16)
O2W—H1W2⋯O1Bⁱⁱⁱ	0.838 (8)	2.453 (13)	3.1535 (11)	141.6 (15)
O1W—H2W1⋯O1A^iv	0.848 (9)	1.907 (10)	2.7227 (10)	160.9 (18)
O1W—H2W1⋯N2A^iv	0.848 (9)	2.550 (16)	3.1072 (11)	124.2 (14)
N1B—H1NB⋯O2W^v	0.859 (9)	2.073 (9)	2.9260 (12)	171.5 (16)
O1W—H1W1⋯O1Bⁱⁱⁱ	0.842 (9)	1.997 (9)	2.8304 (12)	170.2 (17)
C1A—H1AA⋯O1Wⁱ	0.93	2.49	3.3025 (13)	146
C8A—H8AA⋯O1Wⁱ	0.93	2.51	3.2886 (13)	141
C1B—H1BA⋯O2W^v	0.93	2.41	3.3276 (13)	169
C5B—H5BA⋯O1B	0.93	2.42	2.7555 (13)	101
C8B—H8BA⋯O2W^v	0.93	2.48	3.2977 (14)	147
C15A—H15C⋯O2B^vi	0.96	2.58	3.4738 (15)	156
C15B—H15F⋯O2A^vii	0.96	2.58	3.4773 (15)	156
Symmetry codes: (i) x+1, y-1, z; (ii) x, y-1, z; (iii) -x+1, -y+1, -z+1; (iv) x, y+1, z; (v) -x+2, -y+1, -z+1; (vi) x-1, y, z-1; (vii) x-1, y+1, z.

Data collection: APEX2 (Bruker, 2005); cell refinement: APEX2; data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808028328/is2331sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808028328/is2331Isup2.hkl

checkCIF report

Comment top

Hydrazones possessing an azometine —NHN═CH— proton constitute an important class of compounds for new drug development. Therefore, many researchers have synthesized these compounds as target structures and evaluated their biological activities. These observations have been the guides for the development of new hydrazones. Hydrazones containing an azometine —NHN═CH— proton are synthesized by heating the appropriate substituted hydrazines/hydrazides with aldehydes and ketones in solvents like ethanol, methanol, tetrahydrofuran, butanol, glacial acetic acid, ethanol-glacial acetic acid. Another synthetic route for the synthesis of hydrazones is the coupling of aryldiazonium salts with active hydrogen compounds (Rollas & Küçükgüzel, 2007). Hydrazide-hydrazones compounds are not only intermediates but they are also very effective organic compounds in their own right. When they are used as intermediates, coupling products can be synthesized by using the active hydrogen component of the —CONHN═CH— azometine group (Singh et al., 1992). N-Alkyl hydrazides can be synthesized by reduction of hydrazones with NaBH₄ (Ergenç & Günay, 1998), substituted 1,3,4-oxadiazolines can be synthesized when hydrazones are heated in the presence of acetic anhydride (Durgun et al., 1993). Prompted by these review and in continuation of our work (Fun et al., 2008), we herein report the crystal structure of the title compound, (I).

There are two independent molecules (A and B) in the asymmetric unit of (I), with similar geometries (Fig. 1.) The bond lengths and angles are found to have normal values (Allen et al., 1987). The dihedral angle formed by the benzene (C1A–C6A) and (C9A–C14A) rings is 0.11 (5)° in molecule A and that between the benzene (C1B–C6B) and (C9B–C14B) rings is 0.77 (5)° in molecule B, indicating that they are coplanar. In molecule B, an intramolecular C—H···O hydrogen bond generates an S(5) ring motif (Bernstein et al., 1995).

The crystal packing is consolidated by N—H···O, O—H···O, O—H···N and C—H···O inter and intramolecular hydrogen bonding (Table 1). Furthermore, the packing is strengthened by π–π stacking interactions involving the benzene (C1A–C6A) (Cg1) and the symmetry related (C9B–C14B) ring (Cg4) [Cg1···Cg4ⁱ = 3.5021 Å; Cg1—Cg4ⁱⁱ = 3.6403 (6) Å; symmetry codes: (i) 2-x, 1-y, 1-z; (ii) 2-x, -y, 1-z] and the benzene (C9A–C14A) ring (Cg2) and the symmetry related (C9B–C14B) ring (Cg3) [Cg2···Cg3ⁱ = 3.6065 (6) Å; Cg2—Cg3ⁱⁱ = 3.5274 (6) Å; symmetry codes: (i) 2-x, 1-y, 1-z; (ii) 2-x, -y, 1-z] together with O···O = 2.7226 (11) Å, O···N = 2.7072 (10) Å and N···O = 2.7072 (10)–2.8582 (12) Å short contacts. In the crystal packing, the molecules are stacked along the b axis and the adjacent molecules are linked by water molecules to form an infinite one dimensional chain along the [010] direction.

Related literature top

For related literature on hydrazones, see: Rollas & Küçükgüzel (2007); Singh et al. (1992); Ergenç & Günay (1998); Durgun et al. (1993). For related literature, see: Fun et al. (2008). For bond-length data, see: Allen et al. (1987). For graph-set analysis of hydrogen bonding, see: Bernstein et al. (1995).

Experimental top

The title compound was obtained by refluxing 4-nitrrophenyl hydrazide (0.01 mol) and 4-(dimethylamino)benzaldehyde (0.01 mol) in ethanol (30 ml) with the addition of 3 drops of concentrated Sulfuric acid for 3 h. Excess ethanol was removed from the reaction mixture under reduced pressure. The solid product obtained was filtered, washed with water and dried. Crystals suitable for X-ray analysis were obtained from ethanol by slow evaporation.

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: APEX2 (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003).

Figures top

	Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atom numbering scheme.
	Fig. 2. The crystal packing of the title compound, viewed down the a axis, showing infinite 1-D chains along the [010] direction.

N'-[(Z)-4-(Dimethylamino)benzylene]-4-nitrobenzohydrazide monohydrate top

Crystal data top

C₁₆H₁₆N₄O₃·H₂O	Z = 4
M_r = 330.34	F(000) = 696
Triclinic, P1	D_x = 1.427 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.5866 (2) Å	Cell parameters from 9891 reflections
b = 7.1337 (2) Å	θ = 2.2–29.2°
c = 34.4059 (12) Å	µ = 0.11 mm⁻¹
α = 92.113 (2)°	T = 100 K
β = 90.918 (2)°	Block, red
γ = 107.816 (1)°	0.41 × 0.13 × 0.10 mm
V = 1537.42 (8) Å³

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	11039 independent reflections
Radiation source: fine-focus sealed tube	8656 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.028
ϕ and ω scans	θ_max = 32.5°, θ_min = 0.6°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −9→9
T_min = 0.959, T_max = 0.990	k = −10→10
52996 measured reflections	l = −51→51

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)] = 0.048	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.155	H atoms treated by a mixture of independent and constrained refinement
S = 1.08	w = 1/[σ²(F_o²) + (0.0736P)² + 0.5006P] where P = (F_o² + 2F_c²)/3
11039 reflections	(Δ/σ)_max = 0.001
461 parameters	Δρ_max = 0.45 e Å⁻³
8 restraints	Δρ_min = −0.36 e Å⁻³

Crystal data top

C₁₆H₁₆N₄O₃·H₂O	γ = 107.816 (1)°
M_r = 330.34	V = 1537.42 (8) Å³
Triclinic, P1	Z = 4
a = 6.5866 (2) Å	Mo Kα radiation
b = 7.1337 (2) Å	µ = 0.11 mm⁻¹
c = 34.4059 (12) Å	T = 100 K
α = 92.113 (2)°	0.41 × 0.13 × 0.10 mm
β = 90.918 (2)°

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	11039 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2005)	8656 reflections with I > 2σ(I)
T_min = 0.959, T_max = 0.990	R_int = 0.028
52996 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.048	8 restraints
wR(F²) = 0.155	H atoms treated by a mixture of independent and constrained refinement
S = 1.08	Δρ_max = 0.45 e Å⁻³
11039 reflections	Δρ_min = −0.36 e Å⁻³
461 parameters

Special details top

Experimental. The data was collected with the Oxford Cyrosystem Cobra low-temperature attachment.

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
O1A	0.70471 (11)	−0.07582 (12)	0.30351 (2)	0.01918 (16)
O2A	1.23137 (15)	−0.24154 (16)	0.46624 (3)	0.0307 (2)
O3A	1.53442 (13)	−0.13214 (15)	0.43817 (3)	0.02754 (19)
N1A	0.99847 (13)	−0.03980 (13)	0.26697 (2)	0.01355 (15)
N2A	0.89267 (13)	−0.00979 (13)	0.23380 (2)	0.01426 (16)
N3A	1.33845 (15)	−0.17619 (14)	0.43808 (3)	0.01864 (17)
N4A	0.71656 (14)	0.20609 (14)	0.05749 (2)	0.01700 (17)
C1A	1.24033 (15)	−0.04368 (15)	0.33741 (3)	0.01467 (17)
H1AA	1.3181	0.0119	0.3161	0.018*
C2A	1.34633 (15)	−0.06955 (15)	0.37105 (3)	0.01509 (18)
H2AA	1.4945	−0.0333	0.3725	0.018*
C3A	1.22662 (15)	−0.15040 (14)	0.40243 (3)	0.01401 (17)
C4A	1.00511 (16)	−0.20815 (15)	0.40145 (3)	0.01574 (18)
H4AA	0.9283	−0.2628	0.4229	0.019*
C5A	0.90143 (15)	−0.18208 (14)	0.36758 (3)	0.01475 (17)
H5AA	0.7532	−0.2192	0.3663	0.018*
C6A	1.01742 (15)	−0.10065 (14)	0.33537 (3)	0.01233 (16)
C7A	0.89305 (15)	−0.07167 (14)	0.30049 (3)	0.01324 (17)
C8A	1.01208 (15)	0.04600 (14)	0.20449 (3)	0.01353 (17)
H8AA	1.1575	0.0637	0.2074	0.016*
C9A	0.92940 (15)	0.08245 (14)	0.16715 (3)	0.01250 (16)
C10A	0.71074 (15)	0.03692 (14)	0.15792 (3)	0.01435 (17)
H10A	0.6115	−0.0195	0.1764	0.017*
C11A	0.64051 (15)	0.07458 (15)	0.12178 (3)	0.01456 (17)
H11A	0.4948	0.0421	0.1164	0.017*
C12A	0.78608 (15)	0.16157 (14)	0.09285 (3)	0.01284 (17)
C13A	1.00565 (15)	0.20405 (15)	0.10204 (3)	0.01502 (17)
H13A	1.1057	0.2589	0.0836	0.018*
C14A	1.07347 (15)	0.16486 (15)	0.13832 (3)	0.01493 (17)
H14A	1.2190	0.1941	0.1437	0.018*
C15A	0.49080 (18)	0.14199 (19)	0.04745 (3)	0.0236 (2)
H15A	0.4164	0.1962	0.0664	0.035*
H15B	0.4376	0.0007	0.0471	0.035*
H15C	0.4687	0.1865	0.0222	0.035*
C16A	0.86549 (18)	0.26143 (18)	0.02608 (3)	0.0225 (2)
H16A	0.9824	0.3745	0.0344	0.034*
H16B	0.7939	0.2927	0.0039	0.034*
H16C	0.9185	0.1537	0.0192	0.034*
O1B	0.70699 (12)	0.38412 (13)	0.80186 (2)	0.02177 (17)
O2B	1.25253 (15)	0.27622 (16)	0.96674 (3)	0.0316 (2)
O3B	1.55367 (13)	0.37835 (15)	0.93778 (3)	0.02784 (19)
N1B	1.01061 (13)	0.49010 (12)	0.76799 (2)	0.01420 (16)
N2B	0.89598 (14)	0.51210 (12)	0.73516 (3)	0.01539 (16)
N3B	1.35800 (15)	0.33755 (14)	0.93811 (3)	0.01923 (18)
N4B	0.70414 (14)	0.70854 (14)	0.55794 (3)	0.01718 (17)
C1B	1.25594 (15)	0.46004 (15)	0.83674 (3)	0.01543 (18)
H1BA	1.3326	0.5104	0.8150	0.019*
C2B	1.36291 (16)	0.43702 (15)	0.87055 (3)	0.01629 (18)
H2BA	1.5110	0.4714	0.8716	0.020*
C3B	1.24511 (16)	0.36207 (14)	0.90255 (3)	0.01464 (17)
C4B	1.02391 (16)	0.30698 (15)	0.90212 (3)	0.01653 (18)
H4BA	0.9482	0.2558	0.9239	0.020*
C5B	0.91904 (16)	0.33052 (15)	0.86818 (3)	0.01572 (18)
H5BA	0.7708	0.2946	0.8672	0.019*
C6B	1.03316 (15)	0.40749 (14)	0.83543 (3)	0.01277 (16)
C7B	0.90385 (15)	0.42761 (14)	0.80052 (3)	0.01407 (17)
C8B	1.01092 (16)	0.56375 (14)	0.70506 (3)	0.01526 (18)
H8BA	1.1568	0.5830	0.7074	0.018*
C9B	0.92289 (15)	0.59328 (14)	0.66764 (3)	0.01363 (17)
C10B	0.70382 (15)	0.54404 (14)	0.65874 (3)	0.01446 (17)
H10B	0.6059	0.4873	0.6774	0.017*
C11B	0.63122 (15)	0.57871 (15)	0.62253 (3)	0.01458 (17)
H11B	0.4852	0.5445	0.6173	0.017*
C12B	0.77534 (15)	0.66547 (14)	0.59329 (3)	0.01311 (17)
C13B	0.99531 (15)	0.70948 (15)	0.60209 (3)	0.01521 (18)
H13B	1.0941	0.7631	0.5834	0.018*
C14B	1.06500 (15)	0.67355 (14)	0.63834 (3)	0.01509 (18)
H14B	1.2108	0.7036	0.6435	0.018*
C15B	0.47861 (18)	0.64283 (19)	0.54800 (3)	0.0242 (2)
H15D	0.4035	0.6948	0.5672	0.036*
H15E	0.4271	0.5014	0.5473	0.036*
H15F	0.4555	0.6886	0.5229	0.036*
C16B	0.85261 (18)	0.76642 (18)	0.52658 (3)	0.0222 (2)
H16D	0.9674	0.8813	0.5349	0.033*
H16E	0.7797	0.7956	0.5043	0.033*
H16F	0.9088	0.6607	0.5198	0.033*
O1W	0.41887 (12)	0.95772 (12)	0.24824 (2)	0.01787 (15)
O2W	0.53340 (12)	0.38228 (13)	0.24783 (2)	0.02204 (17)
H1NA	1.1237 (17)	−0.049 (3)	0.2650 (5)	0.037 (4)*
H2W2	0.485 (2)	0.2591 (12)	0.2452 (5)	0.046 (5)*
H1W2	0.433 (2)	0.429 (2)	0.2445 (5)	0.042 (5)*
H2W1	0.529 (2)	0.962 (3)	0.2618 (4)	0.048 (5)*
H1NB	1.1465 (14)	0.523 (2)	0.7656 (5)	0.037 (4)*
H1W1	0.397 (3)	0.860 (2)	0.2324 (4)	0.045 (5)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1A	0.0129 (3)	0.0311 (4)	0.0149 (3)	0.0085 (3)	−0.0005 (2)	0.0032 (3)
O2A	0.0315 (4)	0.0487 (6)	0.0149 (4)	0.0152 (4)	0.0023 (3)	0.0136 (4)
O3A	0.0207 (4)	0.0431 (5)	0.0213 (4)	0.0132 (4)	−0.0048 (3)	0.0048 (4)
N1A	0.0129 (3)	0.0204 (4)	0.0095 (3)	0.0083 (3)	−0.0012 (3)	0.0024 (3)
N2A	0.0162 (4)	0.0191 (4)	0.0093 (4)	0.0082 (3)	−0.0026 (3)	0.0015 (3)
N3A	0.0226 (4)	0.0238 (4)	0.0122 (4)	0.0109 (3)	−0.0022 (3)	0.0033 (3)
N4A	0.0198 (4)	0.0230 (4)	0.0093 (4)	0.0078 (3)	0.0004 (3)	0.0048 (3)
C1A	0.0142 (4)	0.0188 (4)	0.0115 (4)	0.0056 (3)	0.0002 (3)	0.0019 (3)
C2A	0.0142 (4)	0.0206 (4)	0.0118 (4)	0.0074 (3)	−0.0011 (3)	0.0009 (3)
C3A	0.0176 (4)	0.0157 (4)	0.0104 (4)	0.0077 (3)	−0.0020 (3)	0.0013 (3)
C4A	0.0173 (4)	0.0172 (4)	0.0135 (4)	0.0059 (3)	0.0017 (3)	0.0049 (3)
C5A	0.0140 (4)	0.0169 (4)	0.0134 (4)	0.0045 (3)	0.0003 (3)	0.0036 (3)
C6A	0.0138 (4)	0.0137 (4)	0.0107 (4)	0.0060 (3)	−0.0003 (3)	0.0016 (3)
C7A	0.0135 (4)	0.0147 (4)	0.0118 (4)	0.0048 (3)	−0.0007 (3)	0.0011 (3)
C8A	0.0143 (4)	0.0155 (4)	0.0115 (4)	0.0055 (3)	−0.0010 (3)	0.0015 (3)
C9A	0.0148 (4)	0.0135 (4)	0.0101 (4)	0.0056 (3)	−0.0003 (3)	0.0016 (3)
C10A	0.0146 (4)	0.0181 (4)	0.0106 (4)	0.0051 (3)	0.0007 (3)	0.0032 (3)
C11A	0.0131 (4)	0.0189 (4)	0.0119 (4)	0.0051 (3)	−0.0001 (3)	0.0031 (3)
C12A	0.0160 (4)	0.0140 (4)	0.0095 (4)	0.0058 (3)	0.0006 (3)	0.0017 (3)
C13A	0.0156 (4)	0.0178 (4)	0.0123 (4)	0.0056 (3)	0.0029 (3)	0.0037 (3)
C14A	0.0137 (4)	0.0178 (4)	0.0141 (4)	0.0058 (3)	0.0008 (3)	0.0028 (3)
C15A	0.0214 (5)	0.0349 (6)	0.0157 (5)	0.0103 (4)	−0.0034 (4)	0.0056 (4)
C16A	0.0262 (5)	0.0283 (5)	0.0126 (5)	0.0070 (4)	0.0032 (4)	0.0062 (4)
O1B	0.0149 (3)	0.0334 (4)	0.0173 (4)	0.0079 (3)	−0.0011 (3)	0.0005 (3)
O2B	0.0323 (5)	0.0511 (6)	0.0146 (4)	0.0157 (4)	0.0034 (3)	0.0141 (4)
O3B	0.0214 (4)	0.0426 (5)	0.0212 (4)	0.0120 (4)	−0.0036 (3)	0.0068 (4)
N1B	0.0150 (4)	0.0176 (4)	0.0107 (4)	0.0059 (3)	−0.0023 (3)	0.0025 (3)
N2B	0.0178 (4)	0.0160 (4)	0.0128 (4)	0.0060 (3)	−0.0045 (3)	0.0013 (3)
N3B	0.0235 (4)	0.0235 (4)	0.0130 (4)	0.0104 (3)	−0.0016 (3)	0.0036 (3)
N4B	0.0186 (4)	0.0228 (4)	0.0110 (4)	0.0071 (3)	0.0004 (3)	0.0043 (3)
C1B	0.0156 (4)	0.0191 (4)	0.0121 (4)	0.0056 (3)	0.0006 (3)	0.0035 (3)
C2B	0.0152 (4)	0.0206 (4)	0.0140 (4)	0.0068 (3)	−0.0005 (3)	0.0035 (3)
C3B	0.0193 (4)	0.0158 (4)	0.0104 (4)	0.0077 (3)	−0.0013 (3)	0.0022 (3)
C4B	0.0188 (4)	0.0180 (4)	0.0137 (4)	0.0064 (3)	0.0021 (3)	0.0037 (3)
C5B	0.0154 (4)	0.0178 (4)	0.0141 (4)	0.0050 (3)	0.0010 (3)	0.0028 (3)
C6B	0.0147 (4)	0.0128 (4)	0.0115 (4)	0.0055 (3)	−0.0011 (3)	0.0004 (3)
C7B	0.0158 (4)	0.0147 (4)	0.0121 (4)	0.0055 (3)	−0.0015 (3)	−0.0005 (3)
C8B	0.0173 (4)	0.0155 (4)	0.0135 (4)	0.0060 (3)	−0.0027 (3)	0.0013 (3)
C9B	0.0159 (4)	0.0131 (4)	0.0125 (4)	0.0054 (3)	−0.0014 (3)	0.0009 (3)
C10B	0.0165 (4)	0.0163 (4)	0.0106 (4)	0.0047 (3)	0.0004 (3)	0.0034 (3)
C11B	0.0143 (4)	0.0174 (4)	0.0122 (4)	0.0048 (3)	−0.0004 (3)	0.0025 (3)
C12B	0.0169 (4)	0.0138 (4)	0.0099 (4)	0.0064 (3)	0.0006 (3)	0.0017 (3)
C13B	0.0154 (4)	0.0171 (4)	0.0138 (4)	0.0056 (3)	0.0022 (3)	0.0031 (3)
C14B	0.0147 (4)	0.0162 (4)	0.0150 (4)	0.0055 (3)	−0.0003 (3)	0.0022 (3)
C15B	0.0203 (5)	0.0376 (6)	0.0161 (5)	0.0105 (4)	−0.0025 (4)	0.0065 (4)
C16B	0.0251 (5)	0.0280 (5)	0.0128 (5)	0.0062 (4)	0.0029 (4)	0.0057 (4)
O1W	0.0143 (3)	0.0264 (4)	0.0148 (3)	0.0091 (3)	−0.0012 (3)	0.0013 (3)
O2W	0.0165 (3)	0.0271 (4)	0.0234 (4)	0.0074 (3)	0.0002 (3)	0.0056 (3)

Geometric parameters (Å, º) top

O1A—C7A	1.2379 (11)	O3B—N3B	1.2317 (12)
O2A—N3A	1.2278 (12)	N1B—C7B	1.3475 (13)
O3A—N3A	1.2315 (12)	N1B—N2B	1.3888 (11)
N1A—C7A	1.3462 (12)	N1B—H1NB	0.859 (9)
N1A—N2A	1.3846 (11)	N2B—C8B	1.2899 (13)
N1A—H1NA	0.850 (9)	N3B—C3B	1.4650 (13)
N2A—C8A	1.2875 (12)	N4B—C12B	1.3753 (12)
N3A—C3A	1.4667 (12)	N4B—C15B	1.4454 (14)
N4A—C12A	1.3751 (12)	N4B—C16B	1.4527 (14)
N4A—C15A	1.4475 (14)	C1B—C2B	1.3911 (13)
N4A—C16A	1.4540 (13)	C1B—C6B	1.3985 (13)
C1A—C2A	1.3892 (13)	C1B—H1BA	0.9300
C1A—C6A	1.3983 (13)	C2B—C3B	1.3847 (14)
C1A—H1AA	0.9300	C2B—H2BA	0.9300
C2A—C3A	1.3838 (13)	C3B—C4B	1.3878 (14)
C2A—H2AA	0.9300	C4B—C5B	1.3888 (14)
C3A—C4A	1.3889 (13)	C4B—H4BA	0.9300
C4A—C5A	1.3884 (13)	C5B—C6B	1.3988 (13)
C4A—H4AA	0.9300	C5B—H5BA	0.9300
C5A—C6A	1.3972 (13)	C6B—C7B	1.4978 (13)
C5A—H5AA	0.9300	C8B—C9B	1.4524 (13)
C6A—C7A	1.4981 (13)	C8B—H8BA	0.9300
C8A—C9A	1.4505 (13)	C9B—C14B	1.4019 (13)
C8A—H8AA	0.9300	C9B—C10B	1.4025 (13)
C9A—C14A	1.4005 (13)	C10B—C11B	1.3847 (13)
C9A—C10A	1.4043 (13)	C10B—H10B	0.9300
C10A—C11A	1.3835 (13)	C11B—C12B	1.4189 (13)
C10A—H10A	0.9300	C11B—H11B	0.9300
C11A—C12A	1.4167 (13)	C12B—C13B	1.4107 (13)
C11A—H11A	0.9300	C13B—C14B	1.3817 (13)
C12A—C13A	1.4119 (13)	C13B—H13B	0.9300
C13A—C14A	1.3857 (13)	C14B—H14B	0.9300
C13A—H13A	0.9300	C15B—H15D	0.9600
C14A—H14A	0.9300	C15B—H15E	0.9600
C15A—H15A	0.9600	C15B—H15F	0.9600
C15A—H15B	0.9600	C16B—H16D	0.9600
C15A—H15C	0.9600	C16B—H16E	0.9600
C16A—H16A	0.9600	C16B—H16F	0.9600
C16A—H16B	0.9600	O1W—H2W1	0.848 (9)
C16A—H16C	0.9600	O1W—H1W1	0.842 (9)
O1B—C7B	1.2396 (12)	O2W—H2W2	0.839 (8)
O2B—N3B	1.2297 (12)	O2W—H1W2	0.838 (8)

C7A—N1A—N2A	118.95 (8)	C7B—N1B—H1NB	125.9 (11)
C7A—N1A—H1NA	122.1 (12)	N2B—N1B—H1NB	115.4 (11)
N2A—N1A—H1NA	118.7 (12)	C8B—N2B—N1B	113.95 (8)
C8A—N2A—N1A	114.85 (8)	O2B—N3B—O3B	123.26 (9)
O2A—N3A—O3A	123.44 (9)	O2B—N3B—C3B	118.35 (9)
O2A—N3A—C3A	118.16 (9)	O3B—N3B—C3B	118.39 (9)
O3A—N3A—C3A	118.40 (9)	C12B—N4B—C15B	119.95 (8)
C12A—N4A—C15A	119.77 (8)	C12B—N4B—C16B	119.70 (9)
C12A—N4A—C16A	119.76 (8)	C15B—N4B—C16B	117.92 (9)
C15A—N4A—C16A	117.83 (9)	C2B—C1B—C6B	120.04 (9)
C2A—C1A—C6A	120.39 (9)	C2B—C1B—H1BA	120.0
C2A—C1A—H1AA	119.8	C6B—C1B—H1BA	120.0
C6A—C1A—H1AA	119.8	C3B—C2B—C1B	118.87 (9)
C3A—C2A—C1A	118.55 (9)	C3B—C2B—H2BA	120.6
C3A—C2A—H2AA	120.7	C1B—C2B—H2BA	120.6
C1A—C2A—H2AA	120.7	C2B—C3B—C4B	122.54 (9)
C2A—C3A—C4A	122.60 (9)	C2B—C3B—N3B	118.80 (9)
C2A—C3A—N3A	118.59 (9)	C4B—C3B—N3B	118.65 (9)
C4A—C3A—N3A	118.82 (9)	C3B—C4B—C5B	118.02 (9)
C5A—C4A—C3A	118.18 (9)	C3B—C4B—H4BA	121.0
C5A—C4A—H4AA	120.9	C5B—C4B—H4BA	121.0
C3A—C4A—H4AA	120.9	C4B—C5B—C6B	120.93 (9)
C4A—C5A—C6A	120.71 (9)	C4B—C5B—H5BA	119.5
C4A—C5A—H5AA	119.6	C6B—C5B—H5BA	119.5
C6A—C5A—H5AA	119.6	C1B—C6B—C5B	119.59 (9)
C5A—C6A—C1A	119.57 (8)	C1B—C6B—C7B	124.01 (9)
C5A—C6A—C7A	117.17 (8)	C5B—C6B—C7B	116.40 (8)
C1A—C6A—C7A	123.22 (8)	O1B—C7B—N1B	122.42 (9)
O1A—C7A—N1A	123.57 (9)	O1B—C7B—C6B	120.50 (9)
O1A—C7A—C6A	120.16 (9)	N1B—C7B—C6B	117.07 (8)
N1A—C7A—C6A	116.26 (8)	N2B—C8B—C9B	122.99 (9)
N2A—C8A—C9A	122.77 (9)	N2B—C8B—H8BA	118.5
N2A—C8A—H8AA	118.6	C9B—C8B—H8BA	118.5
C9A—C8A—H8AA	118.6	C14B—C9B—C10B	117.73 (9)
C14A—C9A—C10A	117.64 (8)	C14B—C9B—C8B	118.20 (9)
C14A—C9A—C8A	118.88 (8)	C10B—C9B—C8B	124.06 (9)
C10A—C9A—C8A	123.48 (8)	C11B—C10B—C9B	120.92 (9)
C11A—C10A—C9A	121.09 (9)	C11B—C10B—H10B	119.5
C11A—C10A—H10A	119.5	C9B—C10B—H10B	119.5
C9A—C10A—H10A	119.5	C10B—C11B—C12B	121.27 (9)
C10A—C11A—C12A	121.35 (9)	C10B—C11B—H11B	119.4
C10A—C11A—H11A	119.3	C12B—C11B—H11B	119.4
C12A—C11A—H11A	119.3	N4B—C12B—C13B	121.07 (9)
N4A—C12A—C13A	121.29 (8)	N4B—C12B—C11B	121.46 (9)
N4A—C12A—C11A	121.36 (8)	C13B—C12B—C11B	117.46 (8)
C13A—C12A—C11A	117.34 (8)	C14B—C13B—C12B	120.49 (9)
C14A—C13A—C12A	120.62 (9)	C14B—C13B—H13B	119.8
C14A—C13A—H13A	119.7	C12B—C13B—H13B	119.8
C12A—C13A—H13A	119.7	C13B—C14B—C9B	122.08 (9)
C13A—C14A—C9A	121.94 (9)	C13B—C14B—H14B	119.0
C13A—C14A—H14A	119.0	C9B—C14B—H14B	119.0
C9A—C14A—H14A	119.0	N4B—C15B—H15D	109.5
N4A—C15A—H15A	109.5	N4B—C15B—H15E	109.5
N4A—C15A—H15B	109.5	H15D—C15B—H15E	109.5
H15A—C15A—H15B	109.5	N4B—C15B—H15F	109.5
N4A—C15A—H15C	109.5	H15D—C15B—H15F	109.5
H15A—C15A—H15C	109.5	H15E—C15B—H15F	109.5
H15B—C15A—H15C	109.5	N4B—C16B—H16D	109.5
N4A—C16A—H16A	109.5	N4B—C16B—H16E	109.5
N4A—C16A—H16B	109.5	H16D—C16B—H16E	109.5
H16A—C16A—H16B	109.5	N4B—C16B—H16F	109.5
N4A—C16A—H16C	109.5	H16D—C16B—H16F	109.5
H16A—C16A—H16C	109.5	H16E—C16B—H16F	109.5
H16B—C16A—H16C	109.5	H2W1—O1W—H1W1	106.7 (12)
C7B—N1B—N2B	118.62 (8)	H2W2—O2W—H1W2	108.6 (12)

C7A—N1A—N2A—C8A	170.93 (9)	C7B—N1B—N2B—C8B	−176.98 (9)
C6A—C1A—C2A—C3A	−0.75 (15)	C6B—C1B—C2B—C3B	−0.12 (15)
C1A—C2A—C3A—C4A	0.60 (15)	C1B—C2B—C3B—C4B	0.67 (16)
C1A—C2A—C3A—N3A	−179.48 (9)	C1B—C2B—C3B—N3B	179.87 (9)
O2A—N3A—C3A—C2A	177.47 (10)	O2B—N3B—C3B—C2B	177.95 (10)
O3A—N3A—C3A—C2A	−2.85 (15)	O3B—N3B—C3B—C2B	−2.44 (15)
O2A—N3A—C3A—C4A	−2.60 (15)	O2B—N3B—C3B—C4B	−2.82 (15)
O3A—N3A—C3A—C4A	177.07 (10)	O3B—N3B—C3B—C4B	176.80 (10)
C2A—C3A—C4A—C5A	−0.35 (15)	C2B—C3B—C4B—C5B	−0.61 (16)
N3A—C3A—C4A—C5A	179.73 (9)	N3B—C3B—C4B—C5B	−179.81 (9)
C3A—C4A—C5A—C6A	0.25 (15)	C3B—C4B—C5B—C6B	0.00 (15)
C4A—C5A—C6A—C1A	−0.42 (15)	C2B—C1B—C6B—C5B	−0.46 (15)
C4A—C5A—C6A—C7A	−178.04 (9)	C2B—C1B—C6B—C7B	179.70 (9)
C2A—C1A—C6A—C5A	0.68 (15)	C4B—C5B—C6B—C1B	0.53 (15)
C2A—C1A—C6A—C7A	178.15 (9)	C4B—C5B—C6B—C7B	−179.62 (9)
N2A—N1A—C7A—O1A	−0.01 (15)	N2B—N1B—C7B—O1B	1.99 (15)
N2A—N1A—C7A—C6A	−179.29 (8)	N2B—N1B—C7B—C6B	−179.45 (8)
C5A—C6A—C7A—O1A	16.42 (14)	C1B—C6B—C7B—O1B	−177.60 (10)
C1A—C6A—C7A—O1A	−161.10 (10)	C5B—C6B—C7B—O1B	2.56 (14)
C5A—C6A—C7A—N1A	−164.26 (9)	C1B—C6B—C7B—N1B	3.81 (14)
C1A—C6A—C7A—N1A	18.21 (14)	C5B—C6B—C7B—N1B	−176.03 (9)
N1A—N2A—C8A—C9A	179.26 (8)	N1B—N2B—C8B—C9B	179.47 (9)
N2A—C8A—C9A—C14A	172.55 (9)	N2B—C8B—C9B—C14B	171.95 (9)
N2A—C8A—C9A—C10A	−8.37 (15)	N2B—C8B—C9B—C10B	−8.92 (16)
C14A—C9A—C10A—C11A	−0.81 (15)	C14B—C9B—C10B—C11B	−1.69 (14)
C8A—C9A—C10A—C11A	−179.90 (9)	C8B—C9B—C10B—C11B	179.17 (9)
C9A—C10A—C11A—C12A	−0.44 (15)	C9B—C10B—C11B—C12B	−0.18 (15)
C15A—N4A—C12A—C13A	173.52 (10)	C15B—N4B—C12B—C13B	173.26 (10)
C16A—N4A—C12A—C13A	12.30 (15)	C16B—N4B—C12B—C13B	11.36 (15)
C15A—N4A—C12A—C11A	−7.65 (15)	C15B—N4B—C12B—C11B	−7.93 (15)
C16A—N4A—C12A—C11A	−168.87 (9)	C16B—N4B—C12B—C11B	−169.83 (9)
C10A—C11A—C12A—N4A	−177.42 (9)	C10B—C11B—C12B—N4B	−176.95 (9)
C10A—C11A—C12A—C13A	1.46 (15)	C10B—C11B—C12B—C13B	1.91 (15)
N4A—C12A—C13A—C14A	177.65 (9)	N4B—C12B—C13B—C14B	177.09 (9)
C11A—C12A—C13A—C14A	−1.23 (14)	C11B—C12B—C13B—C14B	−1.76 (14)
C12A—C13A—C14A—C9A	0.00 (15)	C12B—C13B—C14B—C9B	−0.10 (15)
C10A—C9A—C14A—C13A	1.04 (15)	C10B—C9B—C14B—C13B	1.84 (15)
C8A—C9A—C14A—C13A	−179.83 (9)	C8B—C9B—C14B—C13B	−178.97 (9)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1A—H1NA···O1Wⁱ	0.85 (1)	2.02 (1)	2.8582 (11)	167 (2)
O2W—H2W2···O1Wⁱⁱ	0.84 (1)	2.07 (1)	2.8892 (12)	167 (2)
O2W—H1W2···N2Bⁱⁱⁱ	0.84 (1)	2.44 (1)	3.1989 (12)	152 (2)
O2W—H1W2···O1Bⁱⁱⁱ	0.84 (1)	2.45 (1)	3.1535 (11)	142 (2)
O1W—H2W1···O1A^iv	0.85 (1)	1.91 (1)	2.7227 (10)	161 (2)
O1W—H2W1···N2A^iv	0.85 (1)	2.55 (2)	3.1072 (11)	124 (1)
N1B—H1NB···O2W^v	0.86 (1)	2.07 (1)	2.9260 (12)	172 (2)
O1W—H1W1···O1Bⁱⁱⁱ	0.84 (1)	2.00 (1)	2.8304 (12)	170 (2)
C1A—H1AA···O1Wⁱ	0.93	2.49	3.3025 (13)	146
C8A—H8AA···O1Wⁱ	0.93	2.51	3.2886 (13)	141
C1B—H1BA···O2W^v	0.93	2.41	3.3276 (13)	169
C5B—H5BA···O1B	0.93	2.42	2.7555 (13)	101
C8B—H8BA···O2W^v	0.93	2.48	3.2977 (14)	147
C15A—H15C···O2B^vi	0.96	2.58	3.4738 (15)	156
C15B—H15F···O2A^vii	0.96	2.58	3.4773 (15)	156

Symmetry codes: (i) x+1, y−1, z; (ii) x, y−1, z; (iii) −x+1, −y+1, −z+1; (iv) x, y+1, z; (v) −x+2, −y+1, −z+1; (vi) x−1, y, z−1; (vii) x−1, y+1, z.

Experimental details

Crystal data
Chemical formula	C₁₆H₁₆N₄O₃·H₂O
M_r	330.34
Crystal system, space group	Triclinic, P1
Temperature (K)	100
a, b, c (Å)	6.5866 (2), 7.1337 (2), 34.4059 (12)
α, β, γ (°)	92.113 (2), 90.918 (2), 107.816 (1)
V (Å³)	1537.42 (8)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.11
Crystal size (mm)	0.41 × 0.13 × 0.10

Data collection
Diffractometer	Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2005)
T_min, T_max	0.959, 0.990
No. of measured, independent and observed [I > 2σ(I)] reflections	52996, 11039, 8656
R_int	0.028
(sin θ/λ)_max (Å⁻¹)	0.756

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.048, 0.155, 1.08
No. of reflections	11039
No. of parameters	461
No. of restraints	8
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.45, −0.36

Computer programs: APEX2 (Bruker, 2005), SAINT (Bruker, 2005), SHELXTL (Sheldrick, 2008), SHELXTL and PLATON (Spek, 2003).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1A—H1NA···O1Wⁱ	0.850 (9)	2.024 (10)	2.8582 (11)	166.8 (16)
O2W—H2W2···O1Wⁱⁱ	0.839 (8)	2.066 (9)	2.8892 (12)	166.9 (16)
O2W—H1W2···N2Bⁱⁱⁱ	0.838 (8)	2.435 (11)	3.1989 (12)	151.8 (16)
O2W—H1W2···O1Bⁱⁱⁱ	0.838 (8)	2.453 (13)	3.1535 (11)	141.6 (15)
O1W—H2W1···O1A^iv	0.848 (9)	1.907 (10)	2.7227 (10)	160.9 (18)
O1W—H2W1···N2A^iv	0.848 (9)	2.550 (16)	3.1072 (11)	124.2 (14)
N1B—H1NB···O2W^v	0.859 (9)	2.073 (9)	2.9260 (12)	171.5 (16)
O1W—H1W1···O1Bⁱⁱⁱ	0.842 (9)	1.997 (9)	2.8304 (12)	170.2 (17)
C1A—H1AA···O1Wⁱ	0.93	2.49	3.3025 (13)	146
C8A—H8AA···O1Wⁱ	0.93	2.51	3.2886 (13)	141
C1B—H1BA···O2W^v	0.93	2.41	3.3276 (13)	169
C5B—H5BA···O1B	0.93	2.42	2.7555 (13)	101
C8B—H8BA···O2W^v	0.93	2.48	3.2977 (14)	147
C15A—H15C···O2B^vi	0.96	2.58	3.4738 (15)	156
C15B—H15F···O2A^vii	0.96	2.58	3.4773 (15)	156

Symmetry codes: (i) x+1, y−1, z; (ii) x, y−1, z; (iii) −x+1, −y+1, −z+1; (iv) x, y+1, z; (v) −x+2, −y+1, −z+1; (vi) x−1, y, z−1; (vii) x−1, y+1, z.

Footnotes

‡Permanent address: Department of Physics, Karunya University, Karunya Nagar, Coimbatore 641114, India.

§Department of Studies in Physics, Mangalore University, Mangalagangotri, Mangalore 574199, India.

Acknowledgements

FHK and SRJ thank the Malaysian Government and Universiti Sains Malaysia for the Science Fund grant No. 305/PFIZIK/613312. SRJ thanks Universiti Sains Malaysia for a post-doctoral research fellowship.

References

Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1–S19. CrossRef Web of Science Google Scholar
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 (2005). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Durgun, B. B., Çapan, G., Ergenç, N. & Rollas, S. (1993). Pharmazie, 48, 942–943. CAS PubMed Web of Science Google Scholar
Ergenç, N. & Günay, N. S. (1998). Eur. J. Med. Chem. 33, 143–148. Google Scholar
Fun, H.-K., Patil, P. S., Jebas, S. R., Sujith, K. V. & Kalluraya, B. (2008). Acta Cryst. E64, o1594–o1595. Web of Science CSD CrossRef IUCr Journals Google Scholar
Rollas, S. & Küçükgüzel, S. G. (2007). Molecules, 12, 1910–1939. Web of Science CrossRef PubMed CAS Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Singh, V., Srivastava, V. K., Palit, G. & Shanker, K. (1992). Arzneim. Forsch. Drug. Res. 42, 993–996. CAS Google Scholar
Spek, A. L. (2003). J. Appl. Cryst. 36, 7–13. Web of Science CrossRef CAS IUCr Journals Google Scholar