Synthesis, X-ray crystal structure, Hirshfeld surface analysis and DFT studies of (E)-N′-(2-bromo­benzyl­idene)-4-methylbenzohydrazide

Anitha, A.G.; Arunagiri, C.; Subashini, A.

doi:10.1107/S2056989018017978

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ISSN: 2056-9890

Volume 75| Part 2| February 2019| Pages 109-114

https://doi.org/10.1107/S2056989018017978

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Synthesis, X-ray crystal structure, Hirshfeld surface analysis and DFT studies of (E)-N′-(2-bromobenzylidene)-4-methylbenzohydrazide

Azhagan Ganapathi Anitha,^a Chidambaram Arunagiri ^b ^* and Annamalai Subashini ^c

^aPG & Research Department of Physics, Seethalakshmi Ramaswami College, Tiruchirappalli 620 002, Tamil Nadu, India, ^bPG & Research Department of Physics, Periyar E.V.R. College (Autonomous), Tiruchirappalli 620 023, Tamil Nadu, India, and ^cPG & Research Department of Chemistry, Seethalakshmi Ramaswami College, Tiruchirappalli 620 002, Tamil Nadu, India
^*Correspondence e-mail: arunasuba03@gmail.com

Edited by A. J. Lough, University of Toronto, Canada (Received 12 November 2018; accepted 19 December 2018; online 4 January 2019)

The title molecule, C₁₅H₁₃BrN₂O, displays a trans configuration with respect to the C=N double bond. The dihedral angle between the bromo- and methyl-substituted benzene rings is 16.1 (3)°. In the crystal, molecules are connected by N—H⋯O and weak C—H⋯O hydrogen bonds, forming R₂¹(6) ring motifs and generating chains along the a–axis direction. The optimized structure generated theoretically via density functional theory (DFT) using standard B3LYP functional and 6–311 G(d,p) basis-set calculations renders good support to the experimental data. The HOMO–LUMO behaviour was elucidated to determine the energy gap. The intermolecular interactions were quantified and analysed using Hirshfeld surface analysis.

Keywords: crystal structure; hydrogen bonding; DFT; Hirshfeld surface analysis.

CCDC reference: 1580647

1. Chemical_context

Hydrazones are a class of organic compounds that possess an R1R2C=NNH₂ structural motif. They are related to ketones and aldehydes in which oxygen has been replaced with an NNH₂ group (Rollas & Küçükgüzel, 2007 ). Azomethines, –NHN=CH–, constitute an important class of compounds for new drug development. The reaction of a hydrazine or hydrazide with aldehydes and ketones yields hydrazones. Hydrazones are important in drug design as they act as ligands for metal complexes, organocatalysis and the synthesis of organic compounds. The C=N bond of the hydrazone and the terminal nitrogen atom containing a lone pair of electron is responsible for the physical and chemical properties. The C atom in the hydrazone unit has both electrophilic and nucleophilic character and both the N atoms are nucleophilic, although the amino-type nitrogen is more reactive. As a result of these properties, hydrazones are widely used in organic synthesis. Owing to their ease of preparation and diverse pharmacological potential, much work on hydrazones has been carried out by medicinal chemists to develop agents with better activity and low toxicity profiles. Hydrazones are known to possess diverse biological activities such as antimicrobial, anti–inflammatory, anticancer and antimalarial (Yousef et al., 2003 ; Trepanier et al., 1966 ) and have been evaluated for inhibition of PDE10A, a phosphodiesterase responsible for neurological and psychological disorders such as Parkinson's, schizophrenia and Huntington's disease (Gage et al., 2011 ). The anticonvulsant potential of some hydrazone derivatives having long duration and rapid onset of action have been reported (Kaushik et al., 2010 ), as has their anti-depressant activity (de Oliveira et al., 2011 ).

Schiff bases are used widely in the field of coordination chemistry and have interesting properties (Morshedi et al., 2009 ; Zhou et al., 2006 ; Khanmohammadi et al., 2009 ). These compounds are synthesized by condensation of carbonyl compounds with amines (van den Ancker et al., 2006 ; Hamaker et al., 2010 ). In addition, free Schiff base compounds are reported to possess antimicrobial (Aslantas et al., 2009 ) and non-linear optical (Karakaş et al., 2008 ) properties. Our previous work on (E)-4-bromo-N′ -(2,4-dihydroxybenzylidene)benzohydrazide and (E)-4-toluic -N′-(2,4-dihydroxybenzylidene)benzohydrazide have been recently reported (Arunagiri et al., 2018a ,b ). This work has been a guide for the development of the new Schiff base title compound, which possesses electronic and non-linear properties. As part of our interest in the identification of bioactive compounds, we report herein on its crystal structure.

2. Structural commentary

The molecular structure of the title compound is shown in Fig. 1(a). The molecule adopts an (E) configuration across the C=N bond, joining the hydrazide group and the benzene ring. In the crystal, the dihedral angle between the bromo- and methyl-substituted benzene rings is 16.1 (3)°. The structure was optimized with the Gaussian09W software (Frisch et al., 2009 ) using the DFT–B3LYP/6–311G(d,p) method, providing information about the geometry of the molecule. The optimized structure is shown in Fig. 1(b). The geometrical parameters (Table 1) are mostly within normal ranges, the slight deviations of the theoretical values from those determined experimentally are due to the fact that the optimization is performed in isolated conditions, whereas the crystal environment and hydrogen-bonding interactions affect the results of the X-ray structure (Zainuri et al., 2017 ).

Table 1
Selected geometric parameters (Å,°) for the experimental and DFT structures

	XRD	DFT
Br1—C11	1.891 (6)	1.925
O1—C8	1.225 (6)	1.219
N1—N2	1.379 (5)	1.364
N1—C8	1.351 (6)	1.383
N2—C9	1.270 (6)	1.285
N1—H1	0.837 (19)	1.006
C1—C8	1.485 (6)	1.501
C9—C10	1.470 (8)	1.470
C9—H9	0.930	1.082

N2—N1—C8	119.2 (4)	120.00
C8—N1—H1	123 (4)	117.84
N2—N1—H1	117 (4)	111.31
N1—C8—C1	116.6 (4)	114.46
O1—C8—C1	121.6 (4)	122.20
O1—C8—N1	121.7 (4)	123.33
N2—C9—C10	120.1 (4)	118.62
N2—C9—H9	120.00	122.79

C8—N1—N2—C9	−173.3 (5)	−179.68
N2—N1—C8—O1	−3.5 (7)	2.54
N2—N1—C8—C1	174.64)	−178.45
C2—C1—C8—O1	24.6 (7)	22.94
C2—C1—C8—N1	−153.6 (5)	−156.06
N2—C9—C10—C11	161.4 (5)	−179.93
N2—C9—C10—C15	−19.2 (7)	−0.14
C6—C1—C8—N1	26.3 (7)	25.79

Figure 1
(a) The molecular structure of the title compound, with displacement ellipsoids drawn at the 50% probability level. (b) The optimized structure of the title compound.

The hydrazide unit (N1/N2/C1/C8–C10) is essentially planar, with a maximum deviation from the least-squares plane of 0.099 (4) Å for atom C10. The O1=C8 bond length [1.225 (6) and 1.219 Å for XRD and B3LYP, respectively] indicates single-bond character. The N1—N2 bond length [1.379 (5) Å for XRD and 1.364 Å for B3LYP] is in good agreement with other experimental values (Sivajeyanthi et al., 2017 ). The C—N bond lengths range from a typical single bond [C8—N1 = 1.351 (6) Å] to a double bond [C9=N2 = 1.270 (6) Å (Sivajeyanthi et al., 2017; Arunagiri et al., 2018a,b).

3. Supramolecular features

In the crystal, N1—H1⋯O1ⁱ and C9—H9⋯O1ⁱ hydrogen bonds (Table 2) connect symmetry-related molecules through classical N—H⋯O and weak C—H⋯O hydrogen bonds, forming $[R_{2}^{1}]$ (6) ring motifs and generating [100] chains (Fig. 2).

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O1ⁱ	0.84 (3)	1.96 (3)	2.785 (5)	167 (5)
C9—H9⋯O1ⁱ	0.93	2.38	3.166 (6)	142
Symmetry code: (i) $[x-{\script{1\over 2}}, -y+{\script{1\over 2}}, z]$ .

Figure 2
Part of the crystal structure with hydrogen bonds shown as dashed lines.

4. Hirshfeld surface analysis

Hirshfeld surface analysis (McKinnon et al., 2007 ; Spackman & Jayatilaka, 2009 ) along with decomposed 2D fingerprint plots (Spackman & McKinnon, 2002 ; McKinnon et al., 2004 , 2007) mapped over d_norm, shape-index and curvedness were used to visualize and quantify the intermolecular interactions. The Hirshfeld surface (HS) and fingerprint plots were generated based on the d_i and d_e distances using Crystal Explorer3.1 (Wolff et al., 2012 ) where d_i is the distance from the nearest atom inside the surface, while d_e is the distance from the HS to the nearest atom outside the surface. In the d_norm surfaces, large circular depressions (deep red) are the indicators of hydrogen-bonding contacts whereas other visible spots are due to H⋯H contacts. The dominant H⋯O interaction in the title compound is evident as a bright-red area in Fig. 3 while the light-red spots are due to N—H⋯O and C—H⋯O interactions. The shape-index surface [Fig. 4(a)] conveys information about each donor–acceptor pair and while the curvedness surface [Fig. 4(b)] is effectively divided into sets of patches, respectively. The tiny extent of area and light colour on the surface indicates weaker and longer contacts other than hydrogen bonds. The 2D fingerprint plots in Fig. 5 shows the relative contributions from the various intermolecular contacts (O⋯H, H⋯H, C⋯H, C⋯C, N⋯H, N⋯N, O.·Br and C.·Br) in the crystal structure. The H⋯H contacts (36%) make the largest contribution, followed by C⋯H/H⋯C (28.2%), O⋯H/H⋯O (10.2%) and N⋯H/H⋯N (7.5%), the latter interactions being represented by blue spikes on both sides at the bottom of the plot.

Figure 3
The three-dimensional d_norm surface of the title compound. add contouring levels

Figure 4
Hirshfeld surfaces mapped over (a) shape-index and (b) curvedness for the title compound.

Figure 5
Two-dimensional fingerprint plots with the relative contributions of the various interactions.

5. Frontier molecular orbitals and Molecular electrostatic potential analysis

The highest-occupied molecular orbital (HOMO), which acts as an electron donor, and the lowest-unoccupied molecular orbital (LUMO), which acts as an electron acceptor, are very important parameters for quantum chemistry. If the energy gap is small, then the molecule is highly polarizable and has high chemical reactivity. The energy levels were computed by the DFTB3LYP/6-311G(d,p) method (Becke et al., 1993 ) as implemented in GAUSSIAN09W (Frisch et al., 2009). The electron transition from the HOMO to the LUMO energy level is shown in Fig. 6. The molecular orbital of HOMO contain both σ and π electron-density character, whereas the LUMO is mainly composed of π-orbital density. The energy band gap (ΔE) of the molecule is about 4.42 eV.

Figure 6
The energy band gap of the compound.

The Gauss-Sum2.2 program (O'Boyle et al., 2008 ) was used to calculate group contributions to the molecular orbitals (HOMO and LUMO) and prepare the density of states (DOS) spectrum shown in Fig. 7. The DOS spectrum was formed by convoluting the molecular orbital information with GAUSSIAN curves of unit height. The green and red lines in the DOS spectrum indicate the HOMO and LUMO levels. The DOS spectrum supports the energy gap calculated by HOMO–LUMO analysis. A molecule with a large energy gap is described as hard while one having a small energy gap is known as a soft molecule. Hard molecules are not more polarizable than the soft ones because they require immense excitation energy (Karabacak & Yilan, 2012 ).

Figure 7
The density of states (DOS) spectrum of the compound.

The molecular electrostatic potential is related to the electron density and molecular electrostatic potential (MESP) maps are very useful descriptors for understanding reactive sites for electrophilic and nucleophilic reactions as well as hydrogen-bonding interactions (Sebastian & Sundaraganesan, 2010 ; Luque et al., 2000 ). Different values of the electrostatic potential are represented by different colours: red represents regions of the most electronegative electrostatic potential, blue represents regions of the most positive electrostatic potential and green represents regions of zero potential. The potential increases in the following order: red < orange < yellow < green < blue. Herein, MEP was calculated at the DFT–B3LYP/6–311(d,p) level of theory that was used for optimization. The MESP map for the title molecule is shown in Fig. 8 with a colour range from −0.053 (red) to 0.053 a.u. (blue). The most electrostatically positive region (blue colour) is located in the molecular plane (N–bonded hydrogen atoms of toluic hydrazide), thus explaining N1—H1⋯O1ⁱ hydrogen bond observed in the crystal structure. The map clearly shows that the electron-rich (red) region is spread around the carbonyl oxygen atom whereas the hydrogen atom attached to nitrogen is positively charged (blue).

Figure 8
The molecular electrostatic potential map for the title compound.

6. Database survey

A search of the Cambridge Structural Database (Version 5.39, last update November 2018; Groom et al., 2016 ) revealed closely related compounds that differ in the donor substituents: N′-(4-chlorobenzylidene)-2-hydroxybenzohydrazide (Zhang et al., 2009 ), (E)-N′-[(pyridin-2-yl)methylene]benzohydrazide (Ramesh Babu et al., 2014 ), (E)-N′-(4-methoxybenzylidene)pyridine-3-carbohydrazide dihydrate (Govindarasu et al., 2015 ), (E)-4-bromo-N′-(4-methoxybenzylidene)benzohydrazide(Balasubramani et al., 2018 ), (E)-3-(1H-indol-2-yl)-1-(4-nitrophenyl)prop-2-en-1-one hemihydrate (Zaini et al., 2018 ); (E)-4-bromo-N′-(2,4-dihydroxybenzylidene)benzohydrazide and (E)-4-toluic-N′-(2,4-dihydroxybenzylidene)benzohydrazide (Arunagiri et al., 2018a,b). In our studies of analagous hydrazide dervatives (with Cl or Br replacing the methyl group of the title compound, we have observed similar types of Intramolecular S(6) and intermolecular N—H⋯O hydrogen bonds (between the amide hydrogen and the carbonyl oxygen atoms).

7. Synthesis and crystallization

The title compound was synthesized by the condensation of 4-toluic hydrazide and 2-bromobenzaldehyde (Fig. 9). An ethanol solution (10ml) of 4-toluic hydrazide (0.25 mol) was mixed with ethanol solution of 2-bromobenzaldehyde (10 ml, 0.25 mol) and the reaction mixture was heated at 323 K for half an hour with constant stirring before being was filtered and kept for crystallization. After a period of one week, brown block-shaped crystals of the title compound were obtained.

Figure 9
Reaction scheme.

8. X-ray crystallography and refinement

Crystal data, data collection and structure refinement details are summarized in Table 3. The hydrogen atom on N1 (H1) was located in a difference-Fourier map and freely refined. C-bound hydrogen atoms were placed in calculated positions (C—H = 0.93–0.96 Å) and refined as riding with U_iso(H) =1.2U_eq(C) or 1.5U_eq(C-methyl).

Table 3
Experimental details

Crystal data
Chemical formula	C₁₅H₁₃BrN₂O
M_r	317.18
Crystal system, space group	Orthorhombic, Pna2₁
Temperature (K)	296
a, b, c (Å)	9.6002 (10), 11.5584 (13), 12.5823 (12)
V (Å³)	1396.2 (3)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	2.94
Crystal size (mm)	0.30 × 0.25 × 0.20

Data collection
Diffractometer	Bruker Kappa APEXII CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2004 )
T_min, T_max	0.473, 0.591
No. of measured, independent and observed [I > 2σ(I)] reflections	17816, 2744, 1837
R_int	0.035
(sin θ/λ)_max (Å⁻¹)	0.617

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.037, 0.097, 1.10
No. of reflections	2744
No. of parameters	176
No. of restraints	2
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.42, −0.47
Computer programs: APEX2, SAINT and XPREP (Bruker, 2004), SIR97 (Altomare et al., 1999 ), SHELXL014 (Sheldrick, 2015 ) and ORTEP-3 for Windows (Farrugia, 2012 ).

Supporting information

CCDC reference: 1580647

Crystal structure: contains datablocks global, I, 80R. DOI: https://doi.org/10.1107/S2056989018017978/lh5887sup1.cif

Supporting information file. DOI: https://doi.org/10.1107/S2056989018017978/lh5887Isup2.cml

checkCIF report

Computing details top

Data collection: APEX2 (Bruker, 2004); cell refinement: APEX2 and SAINT (Bruker, 2004); data reduction: SAINT and XPREP (Bruker, 2004); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL014 (Sheldrick, 2015); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: SHELXL2014 (Sheldrick, 2015).

(E)-4-Methyl-N'-(2-bromobenzylidene)benzohydrazide top

Crystal data top

C₁₅H₁₃BrN₂O	F(000) = 640
M_r = 317.18	D_x = 1.509 Mg m⁻³
Orthorhombic, Pna2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2c -2n	Cell parameters from 6594 reflections
a = 9.6002 (10) Å	θ = 2.4–26.0°
b = 11.5584 (13) Å	µ = 2.94 mm⁻¹
c = 12.5823 (12) Å	T = 296 K
V = 1396.2 (3) Å³	Block, brown
Z = 4	0.30 × 0.25 × 0.20 mm

Data collection top

Bruker Kappa APEXII CCD diffractometer	2744 independent reflections
Radiation source: fine-focus sealed tube	1837 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.035
ω and φ scan	θ_max = 26.0°, θ_min = 2.4°
Absorption correction: multi-scan (SADABS; Bruker, 2004)	h = −11→11
T_min = 0.473, T_max = 0.591	k = −14→14
17816 measured reflections	l = −15→15

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)] = 0.037	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.097	H atoms treated by a mixture of independent and constrained refinement
S = 1.10	w = 1/[σ²(F_o²) + (0.0208P)² + 2.2419P] where P = (F_o² + 2F_c²)/3
2744 reflections	(Δ/σ)_max < 0.001
176 parameters	Δρ_max = 0.42 e Å⁻³
2 restraints	Δρ_min = −0.47 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.

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 > 2sigma(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
Br1	0.27412 (5)	0.49846 (5)	0.50267 (12)	0.06555 (18)
O1	0.7807 (3)	0.1961 (4)	0.2048 (3)	0.0633 (11)
N1	0.5643 (4)	0.2641 (4)	0.2337 (3)	0.0430 (10)
N2	0.5965 (5)	0.2925 (4)	0.3373 (3)	0.0464 (11)
C1	0.6174 (5)	0.1750 (4)	0.0649 (3)	0.0390 (10)
C2	0.6886 (5)	0.0846 (4)	0.0191 (5)	0.0529 (14)
H2	0.7632	0.0514	0.0551	0.064*
C3	0.6512 (7)	0.0427 (5)	−0.0791 (5)	0.0632 (15)
H3	0.7000	−0.0193	−0.1080	0.076*
C4	0.5433 (6)	0.0907 (5)	−0.1352 (4)	0.0546 (14)
C5	0.4721 (6)	0.1827 (5)	−0.0902 (4)	0.0526 (13)
H5	0.3987	0.2165	−0.1271	0.063*
C6	0.5085 (4)	0.2251 (4)	0.0089 (5)	0.0446 (10)
H6	0.4599	0.2872	0.0378	0.054*
C7	0.4998 (11)	0.0447 (6)	−0.2424 (6)	0.0834 (19)
H7C	0.4230	0.0894	−0.2689	0.125*
H7A	0.4723	−0.0348	−0.2356	0.125*
H7B	0.5766	0.0503	−0.2910	0.125*
C8	0.6621 (5)	0.2130 (4)	0.1724 (4)	0.0429 (11)
C9	0.4964 (5)	0.3296 (4)	0.3937 (4)	0.0446 (12)
H9	0.4093	0.3413	0.3632	0.053*
C10	0.5182 (5)	0.3543 (3)	0.5071 (5)	0.0435 (10)
C11	0.4290 (6)	0.4236 (4)	0.5651 (4)	0.0530 (13)
C12	0.4514 (8)	0.4419 (5)	0.6726 (4)	0.0726 (19)
H12	0.3908	0.4882	0.7115	0.087*
C13	0.5642 (9)	0.3908 (6)	0.7213 (5)	0.082 (2)
H13	0.5807	0.4039	0.7931	0.098*
C14	0.6504 (9)	0.3224 (6)	0.6660 (5)	0.083 (2)
H14	0.7239	0.2857	0.7004	0.100*
C15	0.6313 (7)	0.3059 (5)	0.5591 (4)	0.0608 (15)
H15	0.6951	0.2617	0.5210	0.073*
H1	0.480 (3)	0.268 (5)	0.217 (4)	0.051 (16)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br1	0.0673 (3)	0.0624 (3)	0.0669 (3)	0.0056 (3)	0.0118 (6)	−0.0006 (3)
O1	0.0301 (18)	0.111 (3)	0.049 (2)	0.006 (2)	−0.0069 (16)	0.001 (2)
N1	0.033 (2)	0.061 (3)	0.035 (2)	−0.001 (2)	−0.0091 (19)	−0.003 (2)
N2	0.045 (3)	0.058 (3)	0.035 (2)	0.000 (2)	−0.009 (2)	−0.002 (2)
C1	0.035 (2)	0.049 (3)	0.033 (2)	−0.004 (2)	0.001 (2)	0.003 (2)
C2	0.046 (3)	0.058 (3)	0.055 (4)	0.011 (2)	0.003 (3)	0.006 (3)
C3	0.067 (4)	0.059 (3)	0.063 (4)	0.002 (3)	0.008 (3)	−0.008 (3)
C4	0.061 (3)	0.062 (3)	0.041 (3)	−0.013 (3)	0.005 (3)	−0.007 (3)
C5	0.052 (3)	0.066 (3)	0.040 (3)	−0.001 (3)	−0.013 (2)	−0.001 (3)
C6	0.038 (2)	0.055 (3)	0.041 (2)	0.0026 (19)	−0.005 (3)	−0.003 (3)
C7	0.097 (4)	0.095 (5)	0.058 (3)	−0.016 (6)	−0.009 (3)	−0.021 (5)
C8	0.029 (2)	0.059 (3)	0.040 (3)	−0.003 (2)	0.000 (2)	0.008 (2)
C9	0.049 (3)	0.046 (3)	0.039 (3)	−0.003 (2)	−0.013 (2)	−0.002 (2)
C10	0.057 (3)	0.041 (2)	0.033 (2)	−0.008 (2)	−0.006 (3)	−0.002 (3)
C11	0.070 (4)	0.045 (3)	0.043 (3)	−0.014 (3)	0.000 (3)	−0.002 (2)
C12	0.116 (6)	0.059 (4)	0.042 (4)	−0.021 (4)	0.016 (4)	−0.006 (3)
C13	0.152 (7)	0.059 (4)	0.034 (3)	−0.030 (4)	−0.021 (4)	−0.003 (3)
C14	0.117 (6)	0.082 (5)	0.050 (4)	−0.001 (5)	−0.043 (4)	0.002 (4)
C15	0.075 (4)	0.054 (3)	0.053 (3)	−0.002 (3)	−0.020 (3)	0.003 (3)

Geometric parameters (Å, º) top

Br1—C11	1.891 (6)	C6—H6	0.9300
O1—C8	1.225 (6)	C7—H7C	0.9600
N1—C8	1.351 (6)	C7—H7A	0.9600
N1—N2	1.379 (5)	C7—H7B	0.9600
N1—H1	0.837 (19)	C9—C10	1.470 (8)
N2—C9	1.270 (6)	C9—H9	0.9300
C1—C2	1.375 (7)	C10—C11	1.381 (7)
C1—C6	1.389 (6)	C10—C15	1.386 (7)
C1—C8	1.485 (6)	C11—C12	1.385 (7)
C2—C3	1.375 (8)	C12—C13	1.378 (10)
C2—H2	0.9300	C12—H12	0.9300
C3—C4	1.371 (8)	C13—C14	1.340 (10)
C3—H3	0.9300	C13—H13	0.9300
C4—C5	1.386 (7)	C14—C15	1.370 (8)
C4—C7	1.508 (9)	C14—H14	0.9300
C5—C6	1.384 (8)	C15—H15	0.9300
C5—H5	0.9300

C8—N1—N2	119.2 (4)	H7C—C7—H7B	109.5
C8—N1—H1	123 (4)	H7A—C7—H7B	109.5
N2—N1—H1	117 (4)	O1—C8—N1	121.7 (4)
C9—N2—N1	116.0 (4)	O1—C8—C1	121.6 (4)
C2—C1—C6	118.6 (5)	N1—C8—C1	116.6 (4)
C2—C1—C8	117.6 (4)	N2—C9—C10	120.1 (4)
C6—C1—C8	123.8 (5)	N2—C9—H9	120.0
C1—C2—C3	121.0 (5)	C10—C9—H9	120.0
C1—C2—H2	119.5	C11—C10—C15	118.1 (5)
C3—C2—H2	119.5	C11—C10—C9	122.5 (5)
C4—C3—C2	121.2 (5)	C15—C10—C9	119.4 (5)
C4—C3—H3	119.4	C10—C11—C12	120.5 (6)
C2—C3—H3	119.4	C10—C11—Br1	122.2 (4)
C3—C4—C5	118.2 (5)	C12—C11—Br1	117.2 (5)
C3—C4—C7	121.8 (6)	C13—C12—C11	119.4 (6)
C5—C4—C7	120.0 (6)	C13—C12—H12	120.3
C6—C5—C4	121.1 (5)	C11—C12—H12	120.3
C6—C5—H5	119.5	C14—C13—C12	120.5 (6)
C4—C5—H5	119.5	C14—C13—H13	119.8
C5—C6—C1	120.0 (5)	C12—C13—H13	119.8
C5—C6—H6	120.0	C13—C14—C15	120.6 (7)
C1—C6—H6	120.0	C13—C14—H14	119.7
C4—C7—H7C	109.5	C15—C14—H14	119.7
C4—C7—H7A	109.5	C14—C15—C10	120.8 (6)
H7C—C7—H7A	109.5	C14—C15—H15	119.6
C4—C7—H7B	109.5	C10—C15—H15	119.6

C8—N1—N2—C9	−173.3 (5)	C6—C1—C8—N1	26.3 (7)
C6—C1—C2—C3	−1.5 (7)	N1—N2—C9—C10	175.7 (4)
C8—C1—C2—C3	178.4 (5)	N2—C9—C10—C11	161.4 (5)
C1—C2—C3—C4	1.0 (8)	N2—C9—C10—C15	−19.2 (7)
C2—C3—C4—C5	−0.2 (8)	C15—C10—C11—C12	−1.2 (7)
C2—C3—C4—C7	−179.2 (6)	C9—C10—C11—C12	178.2 (5)
C3—C4—C5—C6	−0.1 (8)	C15—C10—C11—Br1	178.1 (4)
C7—C4—C5—C6	178.9 (6)	C9—C10—C11—Br1	−2.5 (6)
C4—C5—C6—C1	−0.3 (8)	C10—C11—C12—C13	0.4 (8)
C2—C1—C6—C5	1.1 (7)	Br1—C11—C12—C13	−178.9 (5)
C8—C1—C6—C5	−178.8 (5)	C11—C12—C13—C14	−1.1 (10)
N2—N1—C8—O1	−3.5 (7)	C12—C13—C14—C15	2.8 (11)
N2—N1—C8—C1	174.6 (4)	C13—C14—C15—C10	−3.6 (10)
C2—C1—C8—O1	24.6 (7)	C11—C10—C15—C14	2.8 (8)
C6—C1—C8—O1	−155.5 (5)	C9—C10—C15—C14	−176.6 (6)
C2—C1—C8—N1	−153.6 (5)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1ⁱ	0.84 (3)	1.96 (3)	2.785 (5)	167 (5)
C9—H9···O1ⁱ	0.93	2.38	3.166 (6)	142

Symmetry code: (i) x−1/2, −y+1/2, z.

Selected geometric parameters of XRD and DFT (Å,°) top

	XRD	DFT
Br1—C11	1.891 (6)	1.925
O1—C8	1.225 (6)	1.219
N1—N2	1.379 (5)	1.364
N1—C8	1.351 (6)	1.383
N2—C9	1.270 (6)	1.285
N1—H1	0.837 (19)	1.006
C1—C8	1.485 (6)	1.501
C9—C10	1.470 (8)	1.470
C9—H9	0.930	1.082

N2—N1—C8	119.2 (4)	120.00
C8—N1—H1	123 (4)	117.84
N2—N1—H1	117 (4)	111.31
N1—C8—C1	116.6 (4)	114.46
O1—C8—C1	121.6 (4)	122.20
O1—C8—N1	121.7 (4)	123.33
N2—C9—C10	120.1 (4)	118.62
N2—C9—H9	120.00	122.79

C8—N1—N2—C9	-173.3 (5)	-179.68
N2—N1—C8—O1	-3.5 (7)	2.54
N2—N1—C8—C1	174.64)	-178.45
C2—C1—C8—O1	24.6 (7)	22.94
C2—C1—C8—N1	-153.6 (5)	-156.06
N2—C9—C10—C11	161.4 (5)	-179.93
N2—C9—C10—C15	-19.2 (7)	-0.14
C6—C1—C8—N1	26.3 (7)	25.79

Funding information

AGA thanks the University Grants Commission (UGC), New Delhi, India, for the award of a Research Fellowship under the Faculty Development Programme (FDP).

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