Crystal structure, DFT and Hirshfeld surface analysis of N-acetyl-t-3-methyl-r-2,c-6-di­phenyl­piperidine

Periyannan, P.; Beemarao, M.; Karthik, K. .; Ponnuswamy, S.; Ravichandran, K.

doi:10.1107/S2056989022000275

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Volume 78| Part 2| February 2022| Pages 179-183

https://doi.org/10.1107/S2056989022000275

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Crystal structure, DFT and Hirshfeld surface analysis of N-acetyl-t-3-methyl-r-2,c-6-diphenylpiperidine

P. Periyannan,^a M. Beemarao,^a K . Karthik,^b S. Ponnuswamy ^b and K. Ravichandran ^a ^*

^aDepartment of Physics, Kandaswami Kandar's College, Velur, Namakkal 638 182, India, and ^bPG and Research` Department of Chemistry, Government Arts College (Autonomous), Coimbatore–641018., Tamil Nadu, India
^*Correspondence e-mail: kravichandran05@gmail.com

Edited by J. Reibenspies, Texas A & M University, USA (Received 19 November 2021; accepted 7 January 2022; online 14 January 2022)

In the title compound [systematic name: 1-(3-methyl-2,6-diphenylpiperidin-1-yl)ethanone], C₂₀H₂₃NO, the piperidine ring adopts a distorted boat conformation, while the phenyl rings subtend a dihedral angle 65.1 (2)°. In the crystal, molecules are linked by C—H⋯O hydrogen bonds into chains extending along the b-axis direction. The DFT/B3LYP/6–311 G(d,p) method was used to determine the HOMO–LUMO energy levels. A Hirshfeld surface analysis was conducted to verify the contributions of the different intermolecular interactions, indicating that the important contributions to the crystal packing are from H⋯H (73.2%), C⋯H (18.4%) and O⋯H (8.4%) interactions.

Keywords: crystal structure; 2,6-substituted piperidine; hydrogen bonds; DFT.

CCDC reference: 2133146

1. Chemical context

The structures of a wide array of heterocyclic derivatives have been analysed for their pharma-potentiality over the past three decades (Katritzky, 2010 ). Among these, derivatives of the six-membered heterocyclic base piperidine have proven to be successful pharmacophores. 2,6-Substituted piperidine derivatives have been found to be useful as tranquilizers and possess a wide range of biological activities such as anti-tumor (Vinaya et al., 2009 ), antiviral, antimalarial, antibacterial and antifungal activities (Aridoss et al., 2009 ; Mobio et al., 1989 ). These have spurred considerable awareness of the synthetic arena based on their structure, reactivity, synthesis and biological properties. We report herein the crystal structure, Hirshfeld surface analysis and DFT computational calculations of the title compound.

2. Structural commentary

The methyl-substituted piperidine title compound crystallizes in the monoclinic space group P2₁. A perspective view of the molecule is shown in Fig. 1. The bond lengths and angles are well within the expected limits (Roques et al., 1981 ), and agree with values observed in related structures (Sekar et al., 1990 ).

Figure 1
The molecular structure of the title compound, showing the atomic numbering and displacement ellipsoids drawn at the 30% probability level.

The piperidine ring adopts a distorted boat conformation with puckering parameters (Cremer & Pople, 1975 ) and asymmetry parameters (Nardelli, 1983 ): q₂ = 0.720 (2) Å, q₃ = −0.004 (3) Å, Φ(2) = 108.5 (2)°, ΔCs(C3) and ΔCs(C6) = 14.5 (2)°, and with maximum deviations of 0.406 (3) and 0.409 (2) Å, respectively, for atoms C3 and C6 from the best plane of the piperidine ring. The title molecule contains three chiral centres viz., C2, C5 and C6. The absolute configuration of the chiral centres is assigned as C2 (R), C5 (S) and C6 (S). The parent molecule itself is chiral and the configuration cannot be changed during the substitution of acetyl group at the nitrogen.

The sum of the bond angles (358.2°) at atom N1 of the piperidine ring is in accordance with the sp² hybridization state (Beddoes et al., 1986 ). The phenyl rings at the 2 and 6-positions of the piperidine ring occupy equatorial and axial orientations. The corresponding torsion angles are C4—C3—C2—C13 = −178.8 (2)° and C4—C5—C6—C7 = −74.5 (3)°.

The piperidine ring [N1/C2–C6] makes dihedral angles of 82.0 (1) and 58.4 (1)°, respectively, with the C13–C18 and C7–C12 phenyl rings, and confirms the fact that the moieties are in axial and equatorial orientations. It is to be noted that there is a possibility of resonance between atoms N1, C19 and O1 as a result of the delocalization of the hetero π electrons of the carbonyl group, which is also confirmed by the torsion angles C2—N1—C19—O1 = 177.7 (2)° and C6—N1—C19—O1 = 13.0 (3)°.

The methyl group substituted at the 5-position of the piperidine ring is axially oriented, as confirmed by the torsion angles N1—C6—C5—C21 = −68.0 (3)° and C3—C4—C5—C21 = 112.4 (3)°, whereas the methyl group substituted at C19 is oriented equatorially with torsion angle C20—C19—N1—C6 = −166.3 (2)° and C20—C19—N1—C2 = −1.7 (3)°.

3. Supramolecular features

The crystal packing features C—H⋯O interactions (Table 1). Atom C20 of the molecule at (x, y, z) donates a proton to atom O1 of the molecule at (−x + 1, y + $[{1\over 2}]$ , −z + 1), forming a C4 zigzag chain (Bernstein et al., 1995 ) running along the b-axis direction as shown in Fig. 2. The overall packing is shown in Fig. 3.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C20—H20B⋯O1ⁱ	0.96	2.44	3.292 (3)	148
Symmetry code: (i) $[-x+1, y+{\script{1\over 2}}, -z+1]$ .

Figure 2
A partial view along the b axis of the crystal packing of the title compound, showing the formation of a molecular chain by C—H⋯O interactions (dotted lines).

Figure 3
The overall crystal packing of the title compound, viewed along the b axis. Hydrogen bonds are shown as dashed lines, and only the H atoms involved in hydrogen bonding have been included.

4. Density functional theory (DFT) study

The optimized molecular structure and frontier molecular orbitals (FMOs) (Figs. 4 and 5, respectively) were calculated using the DFT/B3LYP/6-311G(d,p) basis set implemented in the GAUSSIAN09 program package (Frisch et al., 2009 ). The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) are called frontier molecular orbitals (FMOs) as they lie at the outermost boundaries of the electrons of the molecule. The electron distribution (ED) of the HOMO−1, HOMO, LUMO and LUMO+1 energy levels and the energy values are shown in Fig. 5. The positive and negative phases are represented in green and red, respectively.

Figure 4
The optimized molecular structure of the title compound.

Figure 5
The frontier molecular orbitals (FMOs) of the title compound.

The HOMO of the title molecule is localized on one aromatic ring and the C=O group, while the LUMO is located over the whole molecule with the exception of the CH₃ group and some carbon and hydrogen atoms in the piperidine ring. Thus the HOMO/LUMO implies an ED transfer to the C=O group from the ring. The energy band gap (ΔE = E_HOMO − E_LUMO) of the molecule is 3.165 eV and the calculated frontier molecular orbital energies, E_HOMO and E_LUMO, are −5.212 and −2.047 eV, respectively. The title compound has a small frontier orbital gap, hence the molecule has high chemical reactivity and low kinetic stability. The electron affinity (A) and ionization potential (I) of the molecule were calculated using the DFT/B3LYP/6- 311++G(d,p) basis set. The values of the hardness (η), softness (σ), electronegativity (χ) and electrophilicity index (ω) for the title compound are given in Table 2.

Table 2
Physico-chemical properties

Parameter	Value
E_HOMO (eV)	−5.212
E_LUMO (eV)	−2.047
E_HOMO − E_LUMO energy gap (eV)	3.165
E_HOMO−1 (eV)	−5.851
E_LUMO+1 (eV)	−2.248
E_HOMO−1 − E_LUMO+1 energy gap (eV)	3.603
Ionization potential I (eV)	5.212
Electron affinity (A)	2.047
Electrophilicity Index (ω)	4.163
Chemical Potential (μ)	3.629
Electro negativity (χ)	−3.630
Hardness (η)	1.583
Softness (σ)	0.316

5. Hirshfeld surface analysis

In order to visualize the intermolecular interactions in the crystal of the title compound, a Hirshfeld surface (HS) analysis (Spackman & Jayatilaka, 2009 ) was carried out and the associated two-dimensional fingerprint plots (McKinnon et al., 2007 ) were generated using CrystalExplorer17 (Turner et al., 2017 ). The Hirshfeld surface mapped over d_norm using a standard surface resolution with a fixed colour scale of −0.2 (red) to 1.3 (blue) a.u. is shown in Fig. 6a. The shorter and longer contacts are indicated as red and blue spots, respectively, on the Hirshfeld surfaces, and contacts with distances approximately equal to the sum of the van der Waals radii are represented as white spots. The most important red spots on the d_norm surface represent C—H⋯O interactions.

Figure 6
Hirshfeld surfaces mapped over (a) d_norm, (b) shape-index, (c) curvedness and (d) fragment patches.

The HS mapped over curvedness and shape-index, introduced by Koendrink (Koenderink, 1990 ; Koenderink & van Doorn, 1992 ), give further chemical insight into molecular packing. A surface with low curvedness designates a flat region and may be indicative of π–π stacking in the crystal. A surface with high curvedness is highlighted as dark blue edges, and is indicative of the absence of π–π stacking (Fig. 6). The nearest neighbour coordination environment of a molecule is identified from the colour patches on the Hirshfeld surface, depending on their closeness to adjacent molecules (Mohamooda Sumaya et al., 2017 ).

The two-dimensional fingerprint plots of (d_i, d_e) points of all the contacts contributing to the Hirshfeld surface analysis in normal mode for all the atoms are shown in Fig. 7. The most important intermolecular interactions are H⋯H contacts, contributing 73.2% to the overall crystal packing. Other interactions and their respective contributions are C⋯H/H⋯C (18.4%) and O⋯H/H⋯O (8.4%), respectively.

Figure 7
Two-dimensional fingerprint plot for the title compound showing the contributions of individual types of interactions (all intermolecular contacts, H⋯H contacts, C⋯H/H⋯C contacts and O⋯H/H⋯O contacts).

The Hirshfeld surface analysis confirms the importance of H-atom contacts in establishing the packing. The large number of H⋯H and C⋯H/H⋯C interactions suggest that van der Waals interactions and hydrogen bonding play the major roles in the crystal packing (Hathwar et al., 2015 ).

6. Database survey

A search of the Cambridge Structural Database (CSD, version 5.39, update August 2018 ; Groom et al., 2016) for the 3-methyl-2,6-diphenylpiperidine skeleton yielded two hits, methyl 4-oxo-r-2,c-6-diphenylpiperidine-3-carboxylate (BIHZEY; Sampath et al., 2004 ) and r-2,c-6-diphenylpiperidine (NIKYEN; Maheshwaran et al., 2013 ). The piperidine ring has a boat-shaped conformation in both compounds, as in the title compound. The benzene ring and the mean plane of the piperidine ring are inclined to each other by dihedral angles ranging from 19.95 to 29.16°, compared to 22.05 (6)° in the title compound.

7. Synthesis and crystallization

The compound t-3-methyl-r-2,c-6-diphenylpiperidin-4-one was reduced to the corresponding piperidine using the Wolf–Kishner reduction (Ravindran & Jeyaraman, 1992 ). The piperidine-4-one (10 mmol) was treated with diethylene glycol (40 ml), hydrazine hydrate (10 mmol) and KOH pellets (10 mmol) to give t-3-methyl-r-2,c-6-diphenylpiperidine. N-Acetyl piperidine was synthesized by the acetylation of the above piperidine. To t-3-methyl-r-2,c-6-diphenylpiperidine (5 mmol) dissolved in benzene (50 ml) were added triethylamine (20 mmol) and acetyl chloride (20 mmol) to give N-acetyl-t-3-methyl-r-2,c-6-diphenylpiperidine, which was crystallized by slow evaporation from a benzene and petroleum ether solution.

8. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3. H atoms were positioned geometrically (N—H = 0.88–0.90 Å and C—H = 0.93–0.98 Å) and allowed to ride on their parent atoms, with U_iso(H) = 1.5U_eq(C) for methyl H and 1.2U_eq(C) for other H atoms.

Table 3
Experimental details

Crystal data
Chemical formula	C₂₀H₂₃NO
M_r	293.39
Crystal system, space group	Monoclinic, P2₁
Temperature (K)	296
a, b, c (Å)	8.3063 (4), 7.5842 (4), 13.8410 (7)
β (°)	104.174 (2)
V (Å³)	845.39 (7)
Z	2
Radiation type	Mo Kα
μ (mm⁻¹)	0.07
Crystal size (mm)	0.30 × 0.25 × 0.25

Data collection
Diffractometer	Bruker SMART APEXII CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2016 )
T_min, T_max	0.697, 0.745
No. of measured, independent and observed [I > 2σ(I)] reflections	15383, 3447, 2821
R_int	0.024
(sin θ/λ)_max (Å⁻¹)	0.626

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.037, 0.101, 1.03
No. of reflections	3447
No. of parameters	201
No. of restraints	1
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.22, −0.13
Absolute structure	Flack x determined using 1136 quotients [(I⁺)−(I⁻)]/[(I⁺)+(I⁻)] (Parsons et al., 2013 )
Absolute structure parameter	0.0 (5)
Computer programs: APEX2 and SAINT (Bruker, 2016), SHELXS97 and SHELXL97 (Sheldrick, 2008 ), SHELXL2018/3 (Sheldrick, 2015 ), ORTEP-3 for Windows (Farrugia, 2012 ) and PLATON (Spek, 2020 ).

Supporting information

CCDC reference: 2133146

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2056989022000275/jy2013sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989022000275/jy2013Isup2.hkl

checkCIF report

Computing details top

Data collection: APEX2 (Bruker, 2016); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL-2018/3 (Sheldrick, 2015); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2020).

1-(3-Methyl-2,6-diphenylpiperidin-1-yl)ethanone top

Crystal data top

C₂₀H₂₃NO	F(000) = 316
M_r = 293.39	D_x = 1.153 Mg m⁻³
Monoclinic, P2₁	Mo Kα radiation, λ = 0.71073 Å
a = 8.3063 (4) Å	Cell parameters from 2821 reflections
b = 7.5842 (4) Å	θ = 2.6–26.4°
c = 13.8410 (7) Å	µ = 0.07 mm⁻¹
β = 104.174 (2)°	T = 296 K
V = 845.39 (7) Å³	Block, white
Z = 2	0.30 × 0.25 × 0.25 mm

Data collection top

Bruker SMART APEXII CCD diffractometer	2821 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.024
ω and φ scans	θ_max = 26.4°, θ_min = 2.6°
Absorption correction: multi-scan (SADABS; Bruker, 2016)	h = −10→9
T_min = 0.697, T_max = 0.745	k = −9→9
15383 measured reflections	l = −17→17
3447 independent reflections

Refinement top

Refinement on F²	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F² > 2σ(F²)] = 0.037	w = 1/[σ²(F_o²) + (0.0534P)² + 0.0626P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.101	(Δ/σ)_max < 0.001
S = 1.03	Δρ_max = 0.22 e Å⁻³
3447 reflections	Δρ_min = −0.13 e Å⁻³
201 parameters	Absolute structure: Flack x determined using 1136 quotients [(I⁺)-(I^-)]/[(I⁺)+(I^-)] (Parsons et al., 2013)
1 restraint	Absolute structure parameter: 0.0 (5)
Primary atom site location: difference Fourier map

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
C2	0.3371 (3)	0.2057 (3)	0.31568 (16)	0.0457 (5)
H2	0.377220	0.270737	0.378151	0.055*
C3	0.1580 (3)	0.2626 (4)	0.2699 (2)	0.0565 (6)
H3A	0.155366	0.388579	0.257504	0.068*
H3B	0.117951	0.203547	0.206358	0.068*
C4	0.0435 (3)	0.2199 (4)	0.3367 (2)	0.0679 (7)
H4A	−0.070712	0.231457	0.298638	0.081*
H4B	0.061680	0.304992	0.390657	0.081*
C5	0.0700 (3)	0.0344 (4)	0.38074 (17)	0.0567 (6)
H5	−0.038621	−0.023553	0.368498	0.068*
C6	0.1821 (3)	−0.0774 (3)	0.33117 (17)	0.0481 (5)
H6	0.209751	−0.182736	0.372930	0.058*
C7	0.1060 (3)	−0.1457 (3)	0.22655 (17)	0.0502 (5)
C8	−0.0600 (3)	−0.1247 (4)	0.1781 (2)	0.0659 (7)
H8	−0.129032	−0.058009	0.207568	0.079*
C9	−0.1240 (5)	−0.2032 (5)	0.0855 (2)	0.0812 (10)
H9	−0.235412	−0.188306	0.053477	0.097*
C10	−0.0235 (6)	−0.3020 (5)	0.0415 (2)	0.0890 (11)
H10	−0.066947	−0.354500	−0.020068	0.107*
C11	0.1404 (5)	−0.3236 (4)	0.0881 (2)	0.0824 (10)
H11	0.208456	−0.390605	0.058133	0.099*
C12	0.2053 (4)	−0.2460 (4)	0.1796 (2)	0.0637 (7)
H12	0.317158	−0.260974	0.210498	0.076*
C13	0.4446 (3)	0.2557 (3)	0.24606 (16)	0.0471 (5)
C14	0.4544 (3)	0.1539 (4)	0.16487 (19)	0.0584 (6)
H14	0.395691	0.048462	0.152879	0.070*
C15	0.5502 (4)	0.2063 (5)	0.1012 (2)	0.0715 (8)
H15	0.555322	0.136101	0.047006	0.086*
C16	0.6372 (4)	0.3607 (5)	0.1175 (2)	0.0783 (9)
H16	0.701865	0.395466	0.074701	0.094*
C17	0.6289 (4)	0.4638 (4)	0.1971 (3)	0.0775 (9)
H17	0.688101	0.568970	0.208368	0.093*
C18	0.5326 (3)	0.4126 (4)	0.2611 (2)	0.0632 (7)
H18	0.526974	0.484386	0.314655	0.076*
C19	0.4825 (3)	−0.0674 (3)	0.39016 (16)	0.0476 (5)
C20	0.6396 (3)	0.0380 (4)	0.41982 (19)	0.0617 (7)
H20A	0.724197	−0.031394	0.462980	0.093*
H20B	0.619811	0.142671	0.454141	0.093*
H20C	0.675456	0.070131	0.361322	0.093*
C21	0.1416 (4)	0.0413 (5)	0.4921 (2)	0.0733 (8)
H21A	0.155370	−0.076398	0.518301	0.110*
H21B	0.067488	0.105297	0.522752	0.110*
H21C	0.247396	0.099569	0.506051	0.110*
N1	0.3411 (2)	0.0152 (2)	0.33954 (13)	0.0433 (4)
O1	0.4827 (2)	−0.2245 (3)	0.41220 (16)	0.0707 (5)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C2	0.0422 (11)	0.0485 (13)	0.0457 (11)	0.0023 (10)	0.0097 (9)	−0.0057 (10)
C3	0.0478 (13)	0.0552 (14)	0.0642 (14)	0.0106 (11)	0.0097 (11)	0.0003 (12)
C4	0.0484 (14)	0.0814 (19)	0.0771 (17)	0.0154 (14)	0.0216 (13)	−0.0054 (15)
C5	0.0388 (12)	0.0813 (18)	0.0536 (13)	−0.0051 (12)	0.0180 (10)	−0.0059 (13)
C6	0.0379 (11)	0.0585 (13)	0.0484 (11)	−0.0038 (10)	0.0117 (9)	0.0029 (11)
C7	0.0493 (13)	0.0504 (12)	0.0509 (12)	−0.0083 (11)	0.0123 (10)	0.0014 (11)
C8	0.0556 (15)	0.0738 (19)	0.0623 (15)	−0.0092 (14)	0.0029 (12)	−0.0028 (14)
C9	0.080 (2)	0.085 (2)	0.0654 (17)	−0.0241 (17)	−0.0076 (16)	0.0078 (16)
C10	0.122 (3)	0.086 (2)	0.0541 (16)	−0.035 (2)	0.0132 (19)	−0.0097 (16)
C11	0.109 (3)	0.071 (2)	0.0726 (19)	−0.0196 (18)	0.0327 (19)	−0.0186 (16)
C12	0.0700 (17)	0.0594 (15)	0.0644 (15)	−0.0064 (13)	0.0217 (13)	−0.0078 (13)
C13	0.0420 (12)	0.0468 (12)	0.0502 (12)	0.0015 (10)	0.0068 (9)	0.0034 (10)
C14	0.0599 (14)	0.0624 (15)	0.0547 (14)	−0.0057 (12)	0.0173 (12)	−0.0007 (11)
C15	0.0708 (17)	0.088 (2)	0.0616 (15)	0.0017 (16)	0.0277 (14)	0.0080 (15)
C16	0.0658 (18)	0.092 (2)	0.083 (2)	−0.0003 (17)	0.0287 (15)	0.0310 (19)
C17	0.0677 (17)	0.0639 (18)	0.102 (2)	−0.0122 (14)	0.0221 (17)	0.0219 (17)
C18	0.0586 (15)	0.0526 (14)	0.0755 (16)	−0.0018 (12)	0.0110 (13)	0.0047 (13)
C19	0.0417 (12)	0.0580 (14)	0.0444 (11)	0.0082 (11)	0.0129 (9)	0.0067 (10)
C20	0.0361 (11)	0.0821 (18)	0.0650 (14)	0.0069 (12)	0.0085 (10)	0.0051 (14)
C21	0.0709 (18)	0.091 (2)	0.0638 (15)	−0.0030 (16)	0.0278 (13)	0.0006 (16)
N1	0.0335 (9)	0.0520 (10)	0.0445 (9)	0.0014 (8)	0.0100 (7)	0.0023 (8)
O1	0.0595 (12)	0.0657 (12)	0.0843 (13)	0.0117 (9)	0.0125 (10)	0.0206 (10)

Geometric parameters (Å, º) top

C2—N1	1.481 (3)	C11—C12	1.381 (4)
C2—C13	1.513 (3)	C11—H11	0.9300
C2—C3	1.530 (3)	C12—H12	0.9300
C2—H2	0.9800	C13—C14	1.382 (4)
C3—C4	1.515 (4)	C13—C18	1.386 (4)
C3—H3A	0.9700	C14—C15	1.382 (4)
C3—H3B	0.9700	C14—H14	0.9300
C4—C5	1.528 (4)	C15—C16	1.366 (5)
C4—H4A	0.9700	C15—H15	0.9300
C4—H4B	0.9700	C16—C17	1.366 (5)
C5—C21	1.511 (4)	C16—H16	0.9300
C5—C6	1.539 (3)	C17—C18	1.386 (4)
C5—H5	0.9800	C17—H17	0.9300
C6—N1	1.475 (3)	C18—H18	0.9300
C6—C7	1.522 (3)	C19—O1	1.230 (3)
C6—H6	0.9800	C19—N1	1.364 (3)
C7—C8	1.387 (3)	C19—C20	1.499 (4)
C7—C12	1.394 (4)	C20—H20A	0.9600
C8—C9	1.395 (4)	C20—H20B	0.9600
C8—H8	0.9300	C20—H20C	0.9600
C9—C10	1.371 (6)	C21—H21A	0.9600
C9—H9	0.9300	C21—H21B	0.9600
C10—C11	1.366 (5)	C21—H21C	0.9600
C10—H10	0.9300

N1—C2—C13	113.69 (18)	C10—C11—C12	120.1 (3)
N1—C2—C3	109.49 (19)	C10—C11—H11	119.9
C13—C2—C3	109.34 (19)	C12—C11—H11	119.9
N1—C2—H2	108.1	C11—C12—C7	121.2 (3)
C13—C2—H2	108.1	C11—C12—H12	119.4
C3—C2—H2	108.1	C7—C12—H12	119.4
C4—C3—C2	112.3 (2)	C14—C13—C18	117.9 (2)
C4—C3—H3A	109.2	C14—C13—C2	122.6 (2)
C2—C3—H3A	109.2	C18—C13—C2	119.4 (2)
C4—C3—H3B	109.2	C15—C14—C13	121.0 (3)
C2—C3—H3B	109.2	C15—C14—H14	119.5
H3A—C3—H3B	107.9	C13—C14—H14	119.5
C3—C4—C5	112.9 (2)	C16—C15—C14	120.4 (3)
C3—C4—H4A	109.0	C16—C15—H15	119.8
C5—C4—H4A	109.0	C14—C15—H15	119.8
C3—C4—H4B	109.0	C17—C16—C15	119.6 (3)
C5—C4—H4B	109.0	C17—C16—H16	120.2
H4A—C4—H4B	107.8	C15—C16—H16	120.2
C21—C5—C4	110.9 (2)	C16—C17—C18	120.4 (3)
C21—C5—C6	110.1 (2)	C16—C17—H17	119.8
C4—C5—C6	111.90 (19)	C18—C17—H17	119.8
C21—C5—H5	107.9	C13—C18—C17	120.7 (3)
C4—C5—H5	107.9	C13—C18—H18	119.7
C6—C5—H5	107.9	C17—C18—H18	119.7
N1—C6—C7	113.10 (17)	O1—C19—N1	121.4 (2)
N1—C6—C5	109.31 (19)	O1—C19—C20	120.0 (2)
C7—C6—C5	117.12 (19)	N1—C19—C20	118.5 (2)
N1—C6—H6	105.4	C19—C20—H20A	109.5
C7—C6—H6	105.4	C19—C20—H20B	109.5
C5—C6—H6	105.4	H20A—C20—H20B	109.5
C8—C7—C12	118.0 (2)	C19—C20—H20C	109.5
C8—C7—C6	123.5 (2)	H20A—C20—H20C	109.5
C12—C7—C6	118.3 (2)	H20B—C20—H20C	109.5
C7—C8—C9	120.3 (3)	C5—C21—H21A	109.5
C7—C8—H8	119.8	C5—C21—H21B	109.5
C9—C8—H8	119.8	H21A—C21—H21B	109.5
C10—C9—C8	120.3 (3)	C5—C21—H21C	109.5
C10—C9—H9	119.8	H21A—C21—H21C	109.5
C8—C9—H9	119.8	H21B—C21—H21C	109.5
C11—C10—C9	120.1 (3)	C19—N1—C6	117.61 (18)
C11—C10—H10	120.0	C19—N1—C2	122.16 (19)
C9—C10—H10	120.0	C6—N1—C2	118.46 (17)

N1—C2—C3—C4	56.0 (3)	N1—C2—C13—C18	−141.6 (2)
C13—C2—C3—C4	−178.8 (2)	C3—C2—C13—C18	95.7 (3)
C2—C3—C4—C5	−45.0 (3)	C18—C13—C14—C15	0.6 (4)
C3—C4—C5—C21	112.4 (3)	C2—C13—C14—C15	178.1 (2)
C3—C4—C5—C6	−11.0 (3)	C13—C14—C15—C16	0.0 (5)
C21—C5—C6—N1	−68.0 (3)	C14—C15—C16—C17	−0.2 (5)
C4—C5—C6—N1	55.8 (3)	C15—C16—C17—C18	0.0 (5)
C21—C5—C6—C7	161.7 (2)	C14—C13—C18—C17	−0.8 (4)
C4—C5—C6—C7	−74.5 (3)	C2—C13—C18—C17	−178.4 (2)
N1—C6—C7—C8	−133.9 (2)	C16—C17—C18—C13	0.6 (4)
C5—C6—C7—C8	−5.4 (4)	O1—C19—N1—C6	13.1 (3)
N1—C6—C7—C12	51.0 (3)	C20—C19—N1—C6	−166.3 (2)
C5—C6—C7—C12	179.5 (2)	O1—C19—N1—C2	177.7 (2)
C12—C7—C8—C9	0.3 (4)	C20—C19—N1—C2	−1.7 (3)
C6—C7—C8—C9	−174.8 (3)	C7—C6—N1—C19	−108.2 (2)
C7—C8—C9—C10	0.1 (5)	C5—C6—N1—C19	119.4 (2)
C8—C9—C10—C11	−0.3 (5)	C7—C6—N1—C2	86.6 (2)
C9—C10—C11—C12	0.1 (5)	C5—C6—N1—C2	−45.8 (2)
C10—C11—C12—C7	0.4 (5)	C13—C2—N1—C19	64.0 (3)
C8—C7—C12—C11	−0.6 (4)	C3—C2—N1—C19	−173.40 (18)
C6—C7—C12—C11	174.8 (2)	C13—C2—N1—C6	−131.6 (2)
N1—C2—C13—C14	40.9 (3)	C3—C2—N1—C6	−8.9 (3)
C3—C2—C13—C14	−81.8 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C20—H20B···O1ⁱ	0.96	2.44	3.292 (3)	148

Symmetry code: (i) −x+1, y+1/2, −z+1.

Physico-chemical properties top

Parameter	Value
E_HOMO (eV)	-5.212
E_LUMO (eV)	-2.047
E_HOMO - E_LUMO energy gap (eV)	3.165
E_HOMO-1 (eV)	-5.851
E_LUMO+1 (eV)	-2.248
E_HOMO-1 - E_LUMO+1 energy gap (eV)	3.603
Ionization potential I (eV)	5.212
Electron affinity (A)	2.047
Electrophilicity Index (ω)	4.163
Chemical Potential (µ)	3.629
Electro negativity (χ)	-3.630
Hardness (η)	1.583
Softness (σ)	0.316

Acknowledgements

The authors thank the SAIF, IIT Madras, India, for the data collection.

Funding information

KR thanks the UGC, New Delhi, for financial assistance in the form of a Minor Research Project.

References

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