2-{(1E)-[(E)-2-(2,6-Di­chloro­benzyl­idene)hydrazin-1-yl­idene]meth­yl}phenol: crystal structure, Hirshfeld surface analysis and computational study

Manawar, R.B.; Gondaliya, M.B.; Shah, M.K.; Jotani, M.M.; Tiekink, E.R.T.

doi:10.1107/S2056989019012349

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ISSN: 2056-9890

Volume 75| Part 10| October 2019| Pages 1423-1428

https://doi.org/10.1107/S2056989019012349

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2-{(1E)-[(E)-2-(2,6-Dichlorobenzylidene)hydrazin-1-ylidene]methyl}phenol: crystal structure, Hirshfeld surface analysis and computational study

Rohit B. Manawar,^a Mitesh B. Gondaliya,^a Manish K. Shah,^a ‡ Mukesh M. Jotani ^b and Edward R. T. Tiekink ^c ^*

^aChemical Research Laboratory, Department of Chemistry, Saurashtra University, Rajkot - 360005, Gujarat, India, ^bDepartment of Physics, Bhavan's Sheth R. A. College of Science, Ahmedabad, Gujarat - 380001, India, and ^cResearch Centre for Crystalline Materials, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
^*Correspondence e-mail: edwardt@sunway.edu.my

Edited by W. T. A. Harrison, University of Aberdeen, Scotland (Received 3 September 2019; accepted 4 September 2019; online 10 September 2019)

The title Schiff base compound, C₁₄H₁₀Cl₂N₂O, features an E configuration about each of the C=N imine bonds. Overall, the molecule is approximately planar with the dihedral angle between the central C₂N₂ residue (r.m.s. deviation = 0.0371 Å) and the peripheral hydroxybenzene and chlorobenzene rings being 4.9 (3) and 7.5 (3)°, respectively. Nevertheless, a small twist is evident about the central N—N bond [the C—N—N—C torsion angle = −172.7 (2)°]. An intramolecular hydroxy-O—H⋯N(imine) hydrogen bond closes an S(6) loop. In the crystal, π–π stacking interactions between hydroxy- and chlorobenzene rings [inter-centroid separation = 3.6939 (13) Å] lead to a helical supramolecular chain propagating along the b-axis direction; the chains pack without directional interactions between them. The calculated Hirshfeld surfaces point to the importance of H⋯H and Cl⋯H/H⋯Cl contacts to the overall surface, each contributing approximately 29% of all contacts. However, of these only Cl⋯H contacts occur at separations less than the sum of the van der Waals radii. The aforementioned π–π stacking interactions contribute 12.0% to the overall surface contacts. The calculation of the interaction energies in the crystal indicates significant contributions from the dispersion term.

Keywords: crystal structure; Schiff base; Hirshfeld surface analysis; computational chemistry.

CCDC reference: 1857868

1. Chemical context

Being deprotonable and readily substituted with various residues, Schiff base molecules are prominent as multidentate ligands for the generation of a wide variety of metal complexes. In our laboratory, a key motivation for studies in this area arises from our interest in the Schiff bases themselves and of their metal complexes, which are well-known to possess a wide spectrum of biological activity against disease-causing microorganisms (Tian et al., 2009 ; 2011 ). Over and beyond biological considerations, Schiff bases are also suitable for the development of non-linear optical materials because of their solvato-chromaticity (Labidi, 2013 ).

As reported recently, the title compound, (I), a potentially multidentate ligand has anti-bacterial and anti-fungal action against a range of microorganisms (Manawar et al., 2019 ). As a part of complementary structural studies on these molecules, the crystal and molecular structures of (I) are described herein together with a detailed analysis of the calculated Hirshfeld surfaces.

2. Structural commentary

The title Schiff base molecule (I), Fig. 1, features two imine bonds, C7=N1 [1.281 (2) Å] and C8=N2 [1.258 (3) Å] with the configuration about each being E. The central N1, N2, C7, C8 chromophore is close to being the planar, exhibiting an r.m.s. deviation of 0.0371 Å, with deviations of 0.0390 (11) and 0.0372 (10) Å above and below the means plane for the N1 and C7 atoms, respectively. There is a small but significant twist about the central N1—N2 bond [1.405 (2) Å] as seen in the value of the C7—N1—N2—C8 torsion angle of −172.7 (2)°. The dihedral angles between the central plane and those through the hydroxybenzene [4.9 (3)°] and chlorobenzene [7.5 (3)°] rings, respectively, and that between the outer rings [4.83 (13)°] indicate that to a first approximation, the entire molecule is planar. An intramolecular hydroxy-O—H⋯N(imine) hydrogen bond is noted, Table 1, which closes an S(6) loop.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1O⋯N1	0.87 (3)	1.87 (3)	2.632 (2)	147 (3)

Figure 1
The molecular structure of (I)

showing the atom-labelling scheme and displacement ellipsoids at the 35% probability level.

3. Supramolecular features

The most prominent supramolecular association in the crystal of (I) are π–π stacking interactions. These occur between the hydroxy- and chlorobenzene rings with an inter-centroid separation = 3.6939 (13) Å and angle of inclination = 4.32 (11)° [symmetry operation $[{3\over 2}]$ − x, $[{1\over 2}]$ + y, $[{1\over 2}]$ − z]. As these interactions occur at both ends of the molecule and are propagated by screw-symmetry (2₁), the topology of the resultant chain is helical, Fig. 2(a). According to the criteria incorporated in PLATON (Spek, 2009 ), there are no directional interactions connecting chains; a view of the unit-cell contents is shown in Fig. 2(b). The presence of other, weaker points of contact between atoms and between residues are noted – these are discussed in more detail in Hirshfeld surface analysis.

Figure 2
Molecular packing in the crystal of (I)

: (a) supramolecular chain sustained by π(hydroxybenzene)–π(chlorobenzene) interactions shown as purple dashed lines and (b) a view of the unit-cell contents in a projection down the b axis.

4. Hirshfeld surface analysis

The Hirshfeld surface calculations for (I) were performed employing Crystal Explorer 17 (Turner et al., 2017 ) and recently published protocols (Tan et al., 2019 ). On the Hirshfeld surface mapped over d_norm in Fig. 3, the short interatomic contact between the hydroxyphenyl-C2 and chlorophenyl-C12 atoms (Table 2) is characterized as small red spots near them. The Cl1 and Cl2 atoms form short intra-layer Cl⋯H contacts with the H4 and H6 atoms of the hydroxyphenyl ring (Table 2) and are represented in Fig. 4, showing a reference molecule within the Hirshfeld surface mapped over the electrostatic potential. The Hirshfeld surface mapped with curvedness is shown in Fig. 5, which highlights the influence of the short interatomic C⋯C contacts in the packing (Table 2) consistent with the edge-to-edge π–π stacking between symmetry related molecules.

Table 2
Summary of short interatomic contacts (Å) in (I)^a

Contact	Distance	Symmetry operation
Cl1⋯H6	2.86	− $[{1\over 2}]$ + x, $[{1\over 2}]$ − y, − $[{1\over 2}]$ + z
Cl2⋯H4	2.85	$[{1\over 2}]$ + x, $[{1\over 2}]$ − y, $[{1\over 2}]$ + z
O1⋯H7	2.68	$[{1\over 2}]$ + x, $[{1\over 2}]$ − y, $[{1\over 2}]$ + z
C2⋯C12	3.399 (3)	1 − x, − y, 1 − z
Note: (a) The interatomic distances were calculated using Crystal Explorer 17 (Turner et al., 2017) whereby the X—H bond lengths are adjusted to their neutron values.

Figure 3
A view of the Hirshfeld surface for (I)

mapped over d_norm in the range −0.001 to + 1.301 (arbitrary units), highlighting diminutive red spots near the C2 and C12 atoms owing to their participation in C⋯C contacts.

Figure 4
A view of the Hirshfeld surface mapped over the electrostatic potential (the red and blue regions represent negative and positive electrostatic potentials, respectively) in the range −0.065 to + 0.039 atomic units, with short interatomic Cl⋯H and O⋯H contacts highlighted with red and black dashed dashed lines, respectively.

Figure 5
A view of Hirshfeld surface mapped with curvedness showing edge-to-edge π–π overlap through black dashed lines.

The full two-dimensional fingerprint plot for (I), Fig. 6(a), and those decomposed into H⋯H, O⋯H/H⋯O, Cl⋯H/H⋯Cl, C⋯C and C⋯H/H⋯C contacts are illustrated in Fig. 6(b)-(f), respectively. The percentage contributions from the different interatomic contacts to the Hirshfeld surface of (I) are quantitatively summarized in Table 3. It is evident from the fingerprint plot delineated into H⋯H contacts in Fig. 6(b) that their interatomic distances are equal to or greater than the sum of their respective van der Waals radii. The fingerprint plot delineated into O⋯H/H⋯O contacts in Fig. 6(c) indicates the presence of short interatomic O⋯H contacts involving hydroxy-O1 and phenyl-H7 atoms through the pair of forceps-like tips at d_e + d_i < 2.7 Å. The presence of a pair of conical tips at d_e + d_i ∼2.9 Å in the fingerprint plot delineated into Cl⋯H/H⋯Cl contacts in Fig. 6(d) are due to the Cl⋯H contacts listed in Table 2. In the fingerprint plot decomposed into C⋯C contacts in Fig. 6(e), the π–π stacking between symmetry-related hydroxy- and chlorobenzene rings are characterized as the pair of small forceps-like tips at d_e + d_i ∼3.4 Å together with the green points distributed around d_e = d_i ∼1.8 Å. The fingerprint plot delineated into C⋯H/H⋯ C contacts in Fig. 6(f) confirms the absence of significant C—H⋯ π and C⋯H/H⋯C contacts as the points in the respective delineated plot are distributed farther than sum of their respective van der Waals radii. The small contribution from other interatomic contacts to the Hirshfeld surfaces of (I) summarized in Table 3 have a negligible effect on the molecular packing.

Table 3
Percentage contributions of interatomic contacts to the Hirshfeld surface for (I)

Contact	Percentage contribution
H⋯H	29.4
Cl⋯H/H⋯Cl	29.1
O⋯H/H⋯O	7.4
C⋯H/H⋯C	12.0
C⋯C	12.0
N⋯H/H⋯N	4.5
C⋯N/N⋯C	3.9
C⋯Cl/Cl⋯C	0.6
Cl⋯Cl	0.4
Cl⋯N/N⋯Cl	0.4
Cl⋯O/O⋯Cl	0.1
C⋯O/O⋯C	0.1

Figure 6
(a) A comparison of the full two-dimensional fingerprint plot for (I)

and those delineated into (b) H⋯H, (c) O⋯H/H⋯O, (d) Cl⋯H/H⋯Cl, (e) C⋯C and (f) C⋯H/H⋯C contacts.

5. Computational chemistry

In the present analysis, the pairwise interaction energies between the molecules in the crystal were calculated by summing up four different energy components (Turner et al., 2017). These comprise electrostatic (E_ele), polarization (E_pol), dispersion (E_dis) and exchange–repulsion (E_rep), and were obtained using the wave function calculated at the B3LYP/6-31G(d,p) level of theory. From the intermolecular interaction energies collated in Table 4, it is apparent that the dispersion energy component has a major influence in the formation of the supramolecular architecture of (I) as conventional hydrogen bonding is absent. The energy associated with the π–π stacking interaction between symmetry-related hydroxy- and chlorobenzene rings is greater than the energy calculated for the Cl⋯H/H⋯Cl and O⋯H/H⋯O contacts. The magnitudes of intermolecular energies were also represented graphically in Fig. 7 by energy frameworks whereby the cylinders join the centroids of molecular pairs using a red, green and blue colour scheme for the E_ele, E_disp and E_tot components, respectively; the radius of the cylinder is proportional to the magnitude of interaction energy.

Table 4
Summary of interaction energies (kJ mol⁻¹) calculated for (I)

Contact	R (Å)	E_ele	E_pol	E_dis	E_rep	E_tot
C2⋯C12ⁱ	4.00	−13.1	−1.4	−77.2	42.7	−55.8
Cg(C1–C6)⋯Cg(C9–C14)ⁱⁱ	8.58	−5.9	−0.9	−40.1	20.6	−29.2
Cl1⋯H6ⁱⁱⁱ +
Cl2⋯H4^iv +	8.53	−10.4	−1.8	−20.9	19.1	−18.7
O1⋯H7^iv
Symmetry codes: (i) 1 − x, −y, 1 − z; (ii) $[{3\over 2}]$ − x, $[{1\over 2}]$ + y, $[{1\over 2}]$ − z; (iii) − $[{1\over 2}]$ + x, $[{1\over 2}]$ − y, − $[{1\over 2}]$ + z; (iv) $[{1\over 2}]$ + x, $[{1\over 2}]$ − y, $[{1\over 2}]$ + z.

Figure 7
The energy frameworks calculated for (I)

showing the (a) electrostatic potential force, (b) dispersion force and (c) total energy. The energy frameworks were adjusted to the same scale factor of 50 with a cut-off value of 5 kJ mol⁻¹ within 4 × 4 × 4 unit cells

6. Database survey

Given the great interest in Schiff bases and their complexation to transition metals and other heavy elements, it is not surprising that there is a wealth of structural data for these compounds in the Cambridge Structural Database (CSD; Groom et al., 2016 ). Indeed, there are over 150 `hits' for the basic framework 2-OH-C₆—C=N—N=C—C₆ featured in (I). This number is significantly reduced when H atoms are added to the imine-carbon atoms and examples where a second hydroxy substituent present in the 2-position of the phenyl ring is excluded. Thus, there are eight molecules in the CSD containing the fragment 2-OH-C₆-C(H)=N—N=C(H)-C₆, excluding two calix(4)arene derivatives. While the formation of the hydroxy-O—H⋯N(imine) bond is common to all molecules, there is a certain degree of conformational flexibility in the molecules as seen in the relevant geometric data collated in Table 5. From the data in Table 5, the molecule reported herein, i.e. (I), exhibits the greatest twist about the central N—N bond, whereas virtually no twist is seen in the central C—N—N—C torsion angle for (V), i.e. −179.8 (2)°. The dihedral angles between the central C₂N₂ residue and the hydroxy-substituted benzene ring span a range 2.27 (9)°, again in (V), to 10.58 (4)°, for (IV). A significantly greater range is noted in the dihedral angles between C₂N₂ and the second benzene ring, i.e. 2.32 (12)° in (VII) to 29.03 (16)° in (II). Accordingly, the greatest deviation from co-planarity among the nine molecules included in Table 5 is found in (II) where the dihedral angle between the outer rings is 31.35 (8)°.

Table 5
Geometric data (°) for related 2-OH—C₆—C(H)=N—N=C(H)—C₆ molecules, i.e. R¹—C(H)=N—N=C(H)—R²

Compound	R¹	R²	C—N—N—C	C₂N₂/R-C₆	C₂N₂/R′-C₆	R-C₆/R′-C₆	REFCODE
(I)	2-OH—C₆H₄	2,6-Cl₂—C₆H₃	−172.7 (2)	4.9 (3)	7.5 (3)	4.83 (13)	–^a
(II)	2-OH—C₆H₄	anthracen-9-yl	179.1 (2)	2.84 (13)	29.03 (16)	31.35 (8)	KOBXAD^b
(III)	2-OH—C₆H₄	2-EtOC(=O)CH₂—C₆H₄	173.32 (14)	7.25 (9)	20.02 (9)	27.26 (5)	LOSJIO^c
(IV)	2,3-(OH)₂-4,6-(t-Bu)₂—C₆H	4-Me₂NC₆H₄	−178.09 (12)	10.58 (4)	4.61 (4)	15.03 (3)	EDIQOA^d
(V)	2-naphthol	4-Me₂N—C₆H₄	−179.8 (2)	2.27 (9)	6.49 (13)	7.84 (6)	EZUYEF^e
(VI)	2-naphthol	4-OH—C₆H₄	179.30 (16)	3.93 (12)	8.44 (12)	11.91 (6)	RUTGEU^f
(VII)	2-naphthol	4-Me₂N—C₆H₄	177.98 (15)	4.90 (10)	2.32 (12)	3.82 (6)	RUTFET^g
(VIII*	2-naphthol	4-OH-3-MeO-C₆H₄	178.73 (14)	5.78 (10)	15.06 (7)	13.14 (5)	POMNIQ^h
			177.74 (15)	6.65 (9)	12.05 (11)	18.46 (6)
(IX)*	2-naphthol	pyren-1-yl	−173 (1)	2.6 (8)	4.4 (7)	6.9 (4)	APACEBⁱ
			173 (1)	5.3 (7)	4.7 (7)	7.9 (4)
* Two independent molecules in the asymmetric unit. References: (a) This work; (b) Patil & Das (2017 ); (c) Akkurt et al. (2015 ); (d) Arsenyev et al. (2016 ); (e) Ghosh, Adhikari et al. (2016 ); (f) Ghosh, Ta et al. (2016 ); (g) Ghosh, Ta et al. (2016); (h) Kumari et al. (2014 ); (i) Ghosh, Ganguly et al. (2016 )

7. Synthesis and crystallization

Compound (I) was prepared as reported in the literature from the condensation reaction of 2,6-dichlorobenzaldehyde and hydrazine hydrate (Manawar et al., 2019). Crystals in the form of light-yellow blocks for the X-ray study were grown by the slow evaporation of its chloroform solution.

8. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 6. Carbon-bound H-atoms were placed in calculated positions (C—H = 0.93 Å) and were included in the refinement in the riding-model approximation, with U_iso(H) set to 1.2U_eq(C). The position of the O-bound H atom was refined with U_iso(H) set to 1.5U_eq(O).

Table 6
Experimental details

Crystal data
Chemical formula	C₁₄H₁₀Cl₂N₂O
M_r	293.14
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	296
a, b, c (Å)	8.5614 (8), 15.6055 (12), 10.0527 (9)
β (°)	95.031 (3)
V (Å³)	1337.9 (2)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	0.48
Crystal size (mm)	0.35 × 0.30 × 0.30

Data collection
Diffractometer	Bruker Kappa APEXII CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2004 )
T_min, T_max	0.846, 0.867
No. of measured, independent and observed [I > 2σ(I)] reflections	10171, 3185, 2244
R_int	0.023
(sin θ/λ)_max (Å⁻¹)	0.666

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.044, 0.138, 1.05
No. of reflections	3185
No. of parameters	175
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.37, −0.28
Computer programs: APEX2 and SAINT (Bruker, 2004), SIR92 (Altomare et al., 1994 ), SHELXL2014 (Sheldrick, 2015 ), ORTEP-3 for Windows (Farrugia, 2012 ), DIAMOND (Brandenburg, 2006 ) and publCIF (Westrip, 2010 ).

Supporting information

CCDC reference: 1857868

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S2056989019012349/hb7852sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989019012349/hb7852Isup2.hkl

checkCIF report

Computing details top

Data collection: APEX2 (Bruker, 2004); cell refinement: APEX2/SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and DIAMOND (Brandenburg, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).

2-{(1E)-[(E)-2-(2,6-Dichlorobenzylidene)hydrazin-1-\ ylidene]methyl}phenol top

Crystal data top

C₁₄H₁₀Cl₂N₂O	F(000) = 600
M_r = 293.14	D_x = 1.455 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
a = 8.5614 (8) Å	Cell parameters from 4447 reflections
b = 15.6055 (12) Å	θ = 4.8–56.3°
c = 10.0527 (9) Å	µ = 0.48 mm⁻¹
β = 95.031 (3)°	T = 296 K
V = 1337.9 (2) Å³	Block, light-yellow
Z = 4	0.35 × 0.30 × 0.30 mm

Data collection top

Bruker Kappa APEXII CCD diffractometer	2244 reflections with I > 2σ(I)
Radiation source: X-ray tube	R_int = 0.023
ω and φ scan	θ_max = 28.3°, θ_min = 2.6°
Absorption correction: multi-scan (SADABS; Bruker, 2004)	h = −11→11
T_min = 0.846, T_max = 0.867	k = −15→20
10171 measured reflections	l = −11→12
3185 independent 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)] = 0.044	Hydrogen site location: mixed
wR(F²) = 0.138	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	w = 1/[σ²(F_o²) + (0.069P)² + 0.4482P] where P = (F_o² + 2F_c²)/3
3185 reflections	(Δ/σ)_max < 0.001
175 parameters	Δρ_max = 0.37 e Å⁻³
0 restraints	Δρ_min = −0.28 e Å⁻³

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

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

	x	y	z	U_iso*/U_eq
Cl1	0.37913 (8)	−0.06610 (4)	0.23254 (7)	0.0669 (2)
Cl2	0.90894 (8)	−0.10632 (4)	0.57108 (7)	0.0646 (2)
O1	0.8423 (2)	0.25607 (11)	0.52671 (19)	0.0636 (5)
H3O	0.808 (4)	0.206 (2)	0.501 (3)	0.095*
N1	0.66249 (19)	0.14415 (10)	0.39038 (17)	0.0395 (4)
N2	0.6061 (2)	0.06313 (10)	0.34827 (19)	0.0462 (5)
C1	0.7508 (2)	0.31651 (12)	0.4623 (2)	0.0406 (5)
C2	0.6261 (2)	0.29483 (12)	0.36883 (19)	0.0343 (4)
C3	0.5366 (3)	0.36160 (13)	0.3082 (2)	0.0449 (5)
H3	0.4534	0.3486	0.2457	0.054*
C4	0.5688 (3)	0.44563 (15)	0.3390 (2)	0.0555 (6)
H4	0.5073	0.4890	0.2984	0.067*
C5	0.6932 (3)	0.46555 (14)	0.4305 (3)	0.0590 (7)
H5	0.7160	0.5226	0.4505	0.071*
C6	0.7839 (3)	0.40175 (14)	0.4924 (3)	0.0535 (6)
H6	0.8671	0.4158	0.5543	0.064*
C7	0.5859 (2)	0.20707 (12)	0.3350 (2)	0.0378 (4)
H7	0.5026	0.1960	0.2716	0.045*
C8	0.6741 (2)	0.00413 (12)	0.4161 (2)	0.0397 (5)
H8	0.7496	0.0206	0.4834	0.048*
C9	0.6461 (2)	−0.08822 (11)	0.39956 (18)	0.0333 (4)
C10	0.5215 (2)	−0.12658 (13)	0.3210 (2)	0.0389 (5)
C11	0.5039 (3)	−0.21481 (14)	0.3119 (2)	0.0453 (5)
H11	0.4196	−0.2381	0.2594	0.054*
C12	0.6111 (3)	−0.26778 (13)	0.3805 (2)	0.0487 (5)
H12	0.5998	−0.3269	0.3734	0.058*
C13	0.7354 (3)	−0.23366 (13)	0.4599 (2)	0.0459 (5)
H13	0.8080	−0.2694	0.5064	0.055*
C14	0.7504 (2)	−0.14562 (12)	0.4692 (2)	0.0387 (5)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cl1	0.0580 (4)	0.0514 (4)	0.0850 (5)	−0.0036 (3)	−0.0299 (3)	0.0108 (3)
Cl2	0.0631 (4)	0.0443 (3)	0.0800 (5)	0.0068 (3)	−0.0304 (3)	−0.0017 (3)
O1	0.0630 (11)	0.0375 (8)	0.0835 (13)	0.0107 (8)	−0.0322 (9)	−0.0042 (8)
N1	0.0445 (9)	0.0262 (8)	0.0470 (10)	0.0012 (7)	−0.0009 (8)	0.0012 (7)
N2	0.0586 (11)	0.0274 (8)	0.0503 (11)	−0.0011 (8)	−0.0076 (9)	−0.0015 (7)
C1	0.0429 (11)	0.0321 (10)	0.0461 (12)	0.0060 (8)	0.0000 (9)	−0.0012 (8)
C2	0.0393 (10)	0.0284 (9)	0.0356 (10)	0.0048 (8)	0.0047 (8)	0.0015 (8)
C3	0.0543 (12)	0.0381 (11)	0.0414 (11)	0.0098 (9)	−0.0003 (10)	0.0031 (9)
C4	0.0782 (17)	0.0357 (11)	0.0520 (14)	0.0177 (11)	0.0023 (12)	0.0066 (10)
C5	0.0847 (18)	0.0287 (10)	0.0629 (15)	0.0041 (11)	0.0026 (13)	−0.0043 (10)
C6	0.0620 (15)	0.0364 (11)	0.0598 (14)	−0.0004 (10)	−0.0085 (12)	−0.0088 (10)
C7	0.0413 (10)	0.0338 (10)	0.0373 (10)	0.0012 (8)	−0.0020 (8)	0.0001 (8)
C8	0.0389 (10)	0.0315 (9)	0.0478 (12)	−0.0012 (8)	−0.0020 (9)	0.0005 (9)
C9	0.0376 (10)	0.0292 (9)	0.0333 (10)	0.0001 (7)	0.0051 (8)	0.0013 (7)
C10	0.0419 (11)	0.0359 (10)	0.0381 (10)	−0.0009 (8)	−0.0005 (8)	0.0033 (8)
C11	0.0551 (13)	0.0380 (11)	0.0424 (12)	−0.0082 (9)	0.0017 (10)	−0.0042 (9)
C12	0.0688 (15)	0.0285 (10)	0.0496 (13)	−0.0054 (10)	0.0106 (11)	−0.0019 (9)
C13	0.0608 (14)	0.0309 (10)	0.0459 (12)	0.0078 (9)	0.0041 (10)	0.0041 (9)
C14	0.0444 (11)	0.0331 (10)	0.0382 (11)	0.0016 (8)	0.0021 (9)	0.0006 (8)

Geometric parameters (Å, º) top

Cl1—C10	1.725 (2)	C5—C6	1.377 (3)
Cl2—C14	1.739 (2)	C5—H5	0.9300
O1—C1	1.354 (2)	C6—H6	0.9300
O1—H3O	0.87 (3)	C7—H7	0.9300
N1—C7	1.281 (2)	C8—C9	1.468 (3)
N1—N2	1.405 (2)	C8—H8	0.9300
N2—C8	1.258 (3)	C9—C14	1.407 (3)
C1—C6	1.388 (3)	C9—C10	1.405 (3)
C1—C2	1.401 (3)	C10—C11	1.387 (3)
C2—C3	1.401 (3)	C11—C12	1.375 (3)
C2—C7	1.445 (3)	C11—H11	0.9300
C3—C4	1.370 (3)	C12—C13	1.379 (3)
C3—H3	0.9300	C12—H12	0.9300
C4—C5	1.380 (4)	C13—C14	1.382 (3)
C4—H4	0.9300	C13—H13	0.9300

C1—O1—H3O	109 (2)	C2—C7—H7	119.3
C7—N1—N2	114.17 (16)	N2—C8—C9	126.41 (18)
C8—N2—N1	111.38 (17)	N2—C8—H8	116.8
O1—C1—C6	117.72 (19)	C9—C8—H8	116.8
O1—C1—C2	121.84 (17)	C14—C9—C10	115.23 (17)
C6—C1—C2	120.44 (19)	C14—C9—C8	118.56 (17)
C3—C2—C1	117.91 (18)	C10—C9—C8	126.20 (17)
C3—C2—C7	119.52 (18)	C11—C10—C9	122.19 (18)
C1—C2—C7	122.57 (17)	C11—C10—Cl1	116.18 (16)
C4—C3—C2	121.5 (2)	C9—C10—Cl1	121.61 (15)
C4—C3—H3	119.3	C12—C11—C10	120.0 (2)
C2—C3—H3	119.3	C12—C11—H11	120.0
C3—C4—C5	119.6 (2)	C10—C11—H11	120.0
C3—C4—H4	120.2	C13—C12—C11	120.35 (18)
C5—C4—H4	120.2	C13—C12—H12	119.8
C6—C5—C4	120.7 (2)	C11—C12—H12	119.8
C6—C5—H5	119.7	C12—C13—C14	119.0 (2)
C4—C5—H5	119.7	C12—C13—H13	120.5
C5—C6—C1	119.9 (2)	C14—C13—H13	120.5
C5—C6—H6	120.1	C13—C14—C9	123.19 (19)
C1—C6—H6	120.1	C13—C14—Cl2	117.00 (16)
N1—C7—C2	121.47 (18)	C9—C14—Cl2	119.80 (14)
N1—C7—H7	119.3

C7—N1—N2—C8	−172.7 (2)	N2—C8—C9—C14	169.6 (2)
O1—C1—C2—C3	179.3 (2)	N2—C8—C9—C10	−11.4 (4)
C6—C1—C2—C3	−0.3 (3)	C14—C9—C10—C11	−0.6 (3)
O1—C1—C2—C7	0.3 (3)	C8—C9—C10—C11	−179.6 (2)
C6—C1—C2—C7	−179.4 (2)	C14—C9—C10—Cl1	178.08 (15)
C1—C2—C3—C4	−0.2 (3)	C8—C9—C10—Cl1	−0.9 (3)
C7—C2—C3—C4	178.9 (2)	C9—C10—C11—C12	−0.4 (3)
C2—C3—C4—C5	0.8 (4)	Cl1—C10—C11—C12	−179.23 (18)
C3—C4—C5—C6	−0.9 (4)	C10—C11—C12—C13	0.8 (3)
C4—C5—C6—C1	0.3 (4)	C11—C12—C13—C14	0.0 (3)
O1—C1—C6—C5	−179.4 (2)	C12—C13—C14—C9	−1.1 (3)
C2—C1—C6—C5	0.3 (4)	C12—C13—C14—Cl2	179.81 (17)
N2—N1—C7—C2	178.69 (18)	C10—C9—C14—C13	1.4 (3)
C3—C2—C7—N1	−178.4 (2)	C8—C9—C14—C13	−179.5 (2)
C1—C2—C7—N1	0.6 (3)	C10—C9—C14—Cl2	−179.53 (15)
N1—N2—C8—C9	−179.54 (19)	C8—C9—C14—Cl2	−0.5 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1O···N1	0.87 (3)	1.87 (3)	2.632 (2)	147 (3)

Summary of short interatomic contacts (Å) in (I)^a top

Contact	Distance	Symmetry operation
Cl1···H6	2.86	-1/2 + x, 1/2 - y, -1/2 + z
Cl2···H4	2.85	1/2 + x, 1/2 - y, 1/2 + z
O1···H7	2.68	1/2 + x, 1/2 - y, 1/2 + z
C2···C12	3.399 (3)	1 - x, - y, 1 - z

Note: (a) The interatomic distances were calculated using Crystal Explorer 17 (Turner et al., 2017) whereby the X—H bond lengths are adjusted to their neutron values.

Percentage contributions of interatomic contacts to the Hirshfeld surface for (I) top

Contact	Percentage contribution
H···H	29.4
Cl···H/H···Cl	29.1
O···H/H···O	7.4
C···H/H···C	12.0
C···C	12.0
N···H/H···N	4.5
C···N/N···C	3.9
C···Cl/Cl···C	0.6
Cl···Cl	0.4
Cl···N/N···Cl	0.4
Cl···O/O···Cl	0.1
C···O/O···C	0.1

Summary of interaction energies (kJ mol^-1) calculated for (I) top

Contact	R (Å)	E_ele	E_pol	E_dis	E_rep	E_tot
C2···C12ⁱ	4.00	-13.1	-1.4	-77.2	42.7	-55.8
Cg(C1–C6)···Cg(C9–C14)ⁱⁱ	8.58	-5.9	-0.9	-40.1	20.6	-29.2
Cl1···H6ⁱⁱⁱ +
Cl2···H4^iv +	8.53	-10.4	-1.8	-20.9	19.1	-18.7
O1···H7^iv

Symmetry codes: (i) 1 - x, -y, 1 - z; (ii) 3/2 - x, 1/2 + y, 1/2 - z; (iii) -1/2 + x, 1/2 - y, -1/2 + z; (iv) 1/2 + x, 1/2 - y, 1/2 + z.

Geometric data (°) for related 2-OH-C₆—C(H)═N—N═C(H)—C₆ molecules, i.e. R¹—C(H)═N—N═C(H)—R² top

Compound	R¹	R²	C—N—N—C	C₂N₂/R-C₆	C₂N₂/R'-C₆	R-C₆/R'-C₆	REFCODE
(I)	2-OH-C₆H₄	2,6-Cl₂-C₆H₃	-172.7 (2)	4.9 (3)	7.5 (3)	4.83 (13)	–^a
(II)	2-OH-C₆H₄	anthracen-9-yl	179.1 (2)	2.84 (13)	29.03 (16)	31.35 (8)	KOBXAD^b
(III)	2-OH-C₆H₄	2-EtOC(═O)CH₂-C₆H₄	173.32 (14)	7.25 (9)	20.02 (9)	27.26 (5)	LOSJIO^c
(IV)	2,3-(OH)₂-4,6-(t-Bu)₂-C₆H	4-Me₂NC₆H₄	-178.09 (12)	10.58 (4)	4.61 (4)	15.03 (3)	EDIQOA^d
(V)	2-naphthol	4-Me₂N-C₆H₄	-179.8 (2)	2.27 (9)	6.49 (13)	7.84 (6)	EZUYEF^e
(VI)	2-naphthol	4-OH-C₆H₄	179.30 (16)	3.93 (12)	8.44 (12)	11.91 (6)	RUTGEU^f
(VII)	2-naphthol	4-Me₂N-C₆H₄	177.98 (15)	4.90 (10)	2.32 (12)	3.82 (6)	RUTFET^g
(VIII*	2-naphthol	4-OH-3-MeO-C₆H₄	178.73 (14)	5.78 (10)	15.06 (7)	13.14 (5)	POMNIQ^h
			177.74 (15)	6.65 (9)	12.05 (11)	18.46 (6)
(IX)*	2-naphthol	pyren-1-yl	-173 (1)	2.6 (8)	4.4 (7)	6.9 (4)	APACEBⁱ
			173 (1)	5.3 (7)	4.7 (7)	7.9 (4)

* Two independent molecules in the asymmetric unit. References: (a) This work; (b) Patil & Das (2017); (c) Akkurt et al. (2015); (d) Arsenyev et al. (2016); (e) Ghosh, Adhikari et al. (2016); (f) Ghosh, Ta et al. (2016); (g) Ghosh, Ta et al. (2016); (h) Kumari et al. (2014); (i) Ghosh, Ganguly et al. (2016)

Footnotes

‡Additional correspondence author, email: drmks2000hotmail.com.

Acknowledgements

The authors thank the Department of Chemistry, Saurashtra University, Rajkot, Gujarat, India, for access to the chemical synthesis laboratory and to the Sophisticated Test and Instrumentation Centre (SITC), Kochi, Kerala, India, for providing the X-ray intensity data.

Funding information

Crystallographic research at Sunway University is supported by Sunway University Sdn Bhd (grant No. STR-RCTR-RCCM-001-2019).

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