Synthesis, characterization, and crystal structure of 2-(2-azido­phen­yl)-3-oxo-3H-indole 1-oxide

Dhote, P.; Tothadi, S.; Ramana, C.V.

doi:10.1107/S2056989024001440

research communications

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ISSN: 2056-9890

Volume 80| Part 3| March 2024| Pages 310-313

https://doi.org/10.1107/S2056989024001440

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Synthesis, characterization, and crystal structure of 2-(2-azidophenyl)-3-oxo-3H-indole 1-oxide

Pawan Dhote,^a Srinu Tothadi ^b ^* and Chepuri V. Ramana ^a ^*

^aOrganic Chemistry Division, CSIR-National Chemical Laboratory, Pune, 411008, India, and ^bAnalytical and Environmental Sciences Division and Centralized Instrumentation Facility, CSIR-Central Salt and Marine Chemicals Research Institute, Gijubhai Badheka Marg, Bhavnagar, 364002 , India
^*Correspondence e-mail: srinut@csmcri.res.in, vr.chepuri@ncl.res.in

Edited by D. Chopra, Indian Institute of Science Education and Research Bhopal, India (Received 26 October 2023; accepted 13 February 2024; online 20 February 2024)

An attempt to explore the reactivity of the nitro group in the presence of gold catalysis in comparison to the azide group yielded intriguing results. Surprisingly, only the nitro group exhibited reactivity, ultimately giving rise to the formation of the title isatogen, C₁₄H₈N₄O₂. In the crystal structure, weak C—H⋯O hydrogen bonds and π–π stacking interactions link the molecules. The structure exhibits disorder of the molecule.

Keywords: crystal structure; isatogen; reactivity; hydrogen bonding.

CCDC reference: 2303503

1. Chemical context

2,2-Disubstituted indolin-3-ones play a crucial role as fundamental structural motifs in various natural alkaloids and bioactive molecules (Dhote, Patel et al., 2021 ; Ji et al., 2019 ; Gu et al., 2014 ). Thus, substantial research efforts have been dedicated to the synthesis of these essential compounds (Dhote, Patel et al., 2021; Wang et al., 2021 ; Liu & McWhorter, 2003 ; Wetzel & Gagosz, 2011 ; Liu et al., 2003). These synthetic methods can be broadly sorted into three main strategies, viz. oxidative dearomatization of indoles (Wang et al., 2021; Liu et al., 2020 ), cyclization reactions (Dhote, Pund & Ramana, 2021 ; Xie et al., 2021 ; Fu & Song, 2018 ) and nucleophilic additions to 3H-indol-3-ones or indolone-N-oxides (Zhang et al., 2017 ; Liu et al., 2003; Berti et al., 1975 ). Notably, indolone-N-oxides, also known as isatogens, hold substantial importance in medicinal chemistry and serve as intermediates in the synthesis of natural alkaloids and bioactive compounds (Nepveu et al., 2010 ). The literature contains a wide array of techniques for synthesizing isatogens, encompassing both metal-free and metal-catalyzed routes (Dhote & Ramana, 2021 ; Dhote, Halnor et al., 2021 ). These methods have been rigorously explored and well documented, underscoring the adaptability and importance of isatogens in the realms of organic synthesis and medicinal chemistry. Over the past few years, our research group has been deeply involved in this field, particularly focusing on their synthesis through nitroalkyne cycloisomerization (Dhote, Pund & Ramana, 2021; Dhote & Ramana, 2019 ; Kumar & Ramana, 2014 , 2015 ; Patel et al., 2010 ) and we have demonstrated their utility in total synthesis endeavors (Patel et al., 2014 ; Reddy & Ramana, 2013 ; Kumar et al., 2012 ; Patel & Ramana, 2012 ).

As part of our efforts to demonstrate the reactivity of the nitro group compared to the azide group (Dhote & Ramana, 2022 ; Dhote, Halner et al., 2021), we designed a substrate that incorporates both a nitro group and an azide group positioned ortho to an alkyne functionality. Interestingly, when we subjected this substrate to treatment with either Au^III or Au^I, we obtained isatogen 2 with the azide moiety intact in relatively good yield (see reaction scheme below). The structural characterization of 2-(2-azidophenyl)-3-oxo-3H-indole 1-oxide, 2, was achieved through spectral and analytical data analysis. In the ¹H NMR spectra of 2, the protons were observed to be overlapping, posing challenges in confirming the precise structure. Subsequently, the ¹³C NMR spectrum indicated the absence of the alkyne carbon signal, suggesting a modification at the alkyne functionality (see Figs. S1 and S2 in the supporting information). Additionally, signals corresponding to the carbonyl and the newly formed quaternary center were observed at δ = 185.2 and 140.2 ppm, respectively. The molecular composition of compound 2 was further verified as C₁₄H₉N₄O₂ through high-resolution mass spectrometry ([M + H]⁺ found as 265.0771). Moreover, the structure of 2 was conclusively confirmed through single-crystal X-ray diffraction analysis.

2. Structural commentary and supramolecular features

The title compound crystallizes in space group P-1 with one molecule in the asymmetric unit (Fig. 1). Molecules are further connected via C—H⋯O (Table 1) weak hydrogen bonds (Desiraju et al., 1999 ) along the b-axis direction (Fig. 2). Moreover, π–π stacking [3.354 (2) Å; Chipot et al., 1996 ; Chen et al., 2018 ) is observed along the a-axis direction (Fig. 3). However, there are no classical hydrogen bonds present in the crystal packing.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C5—H5⋯O2ⁱ	0.95	2.43	3.1077 (16)	128
C11—H11⋯O1ⁱⁱ	0.95	2.57	3.2327 (17)	127
Symmetry codes: (i) ; (ii) .

Figure 1
ORTEP diagram of 2 with 50% probability displacement ellipsoids. Only one molecule is present in the asymmetric unit.

Figure 2
The packing of molecules via C—H⋯O hydrogen bonds along the b-axis direction. The blue lines depict the intermolecular interactions.

Figure 3
The single-crystal structure of 2. π–π stacking [centroid–centroid distance = 3.354 (2) Å] can be seen along the a-axis direction.

In general, C=O bond lengths (1.22 Å) are always shorter than N⁺—O⁻ (1.26 Å). However, in the current scenario, the C=O and N⁺—O⁻ bond lengths are almost equal (Table 2). We therefore analyzed the bond lengths in similar structures found in the Cambridge Structural Database (Conquest 2023.3.0; CSD version 5.45, update of November 2023; Groom et al., 2016 ), among which seven show N/C disorder and two have similar bond lengths to those in the title compound. We analyzed the bond lengths of similar molecules in the CSD database and further modeled the disorder in the current molecule. After modeling the disorder, the R factor reduced to 4.22%. Predominantly, if the atoms of molecules are disordered, the bond distance are averaged out and shows the mean distance of bonds. The N (N1A and N17A) and C (C1B and C17) atoms of isatogen are disordered over two positions with equal (0.5) site occupancy. As the molecule exhibits disorder, the bond distances were averaged out, giving N17A—O1/C17=O1 = 1.252 (1) Å and C1B=O2/N1A—O2 = 1.248 (1) Å.

Table 2
Covalent C=O/N⁺—O⁻ bond lengths (Å) in 2 and related structures

Compound	C=O/N⁺—O⁻	N⁺—O⁻/C=O
SAWYAR	1.240 (4)	1.241 (4)
SAZQIU	1.253 (2)	1.243 (4)
2	1.252 (1)	1.248 (1)

3. Hirshfeld surface analysis

A Hirshfeld surface analysis of compound 2 was undertaken with CrystalExplorer 21.5 (Spackman et al., 2021 ) to investigate the intermolecular interactions. The overall 2D fingerprint plot is shown in Fig. 4a and those delineated into H⋯H (19.4%), H⋯C/C⋯H (14.9%), H⋯N/N⋯H (22.1%), and H⋯O/O⋯H (23.1%) interactions are shown in Fig. 4b–e. Interactions such as N⋯O/O⋯N O⋯C/C⋯O and N⋯C/ C⋯N contribute very little to the overall surface and hence those contacts are not shown. The Hirshfeld surface mapped with d_norm is shown in Fig. 4f (d_norm is the normalized sum of d_e and d_i where d_e is the distance from the Hirshfeld surface to the nearest atom i internal to the surface and d_i is distance from Hirshfeld surface to the nearest atom e external to the surface).

Figure 4
The two-dimensional fingerprint plots for 2, showing interactions: (a) all interactions and delineated into (b) H⋯H contacts; (c) H⋯C/C⋯H contacts; (d) H⋯N/N⋯H contacts and (e) H⋯O/O⋯H contacts; (f) Hirshfeld surface mapped with d_norm.

4. Database survey

There are twenty structures of isatogen present in the Cambridge Structural Database (CSD; Conquest 2023.3.0; CSD version 5.45, update of November 2023; Groom et al., 2016), among which ten show N/C disorder. Bond lengths associated with these atoms are unusual. In most crystal structures, C=O is always less than N⁺—O⁻. In contrast, the C=O and N⁺—O⁻ bond lengths in SAWYAR (Clegg, 2005 ) and SAZQIU (Clegg & Elsegood, 2005 ) are almost equal and are similar to those the title compound (Table 2).

5. Synthesis and crystallization

The reaction was carried out at room temperature and under an argon atmosphere. To a solution of the active gold complex prepared from JohnPhosAuCl (5 mol%) and AgSbF₆ (10 mol%) or AuCl₃ (5 mol%) in 1,2-DCE (1 ml) was added a solution of 1-azido-2-[(2 nitrophenyl)ethynyl]benzene, 1, in 1,2-DCE (0.5 ml) dropwise over 5 minutes. The resulting solution was stirred for a period of 2 h and then concentrated under reduced pressure. The resulting crude product was purified by column chromatography to afford 2-(2-azidophenyl)-3-oxo-3H-indole 1-oxide, 2, as a yellow solid. Next, single crystals were grown by slow evaporation of a solution of compounds (10 mg) in acetonitrile (1 ml) [placed in a long glass vial of 2 ml volume and closed with a cotton plug] at room temperature in a dark place.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3. H atoms were positioned geometrically (C—H = 0.95 Å) and refined as riding with U_iso(H) = 1.2U_eq(C).

Table 3
Experimental details

Crystal data
Chemical formula	C₁₄H₈N₄O₂
M_r	264.24
Crystal system, space group	Triclinic, P $[\overline{1}]$
Temperature (K)	100
a, b, c (Å)	7.166 (2), 7.686 (3), 12.172 (4)
α, β, γ (°)	95.473 (16), 105.226 (12), 113.116 (13)
V (Å³)	579.9 (3)
Z	2
Radiation type	Mo Kα
μ (mm⁻¹)	0.11
Crystal size (mm)	0.12 × 0.06 × 0.05

Data collection
Diffractometer	Bruker D8 VENTURE Kappa Duo PHOTON II CPAD
Absorption correction	Multi-scan (SADABS; Krause et al., 2015 )
T_min, T_max	0.626, 0.745
No. of measured, independent and observed [I > 2σ(I)] reflections	45548, 4818, 3946
R_int	0.049
(sin θ/λ)_max (Å⁻¹)	0.811

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.042, 0.122, 1.05
No. of reflections	4818
No. of parameters	181
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.46, −0.29
Computer programs: APEX2 and SAINT (Bruker, 2015 ), SHELXT2014/5 (Sheldrick, 2015a ), SHELXL (Sheldrick, 2015b ) and OLEX2 (Dolomanov et al., 2009 ).

Supporting information

CCDC reference: 2303503

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2056989024001440/dx2056sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989024001440/dx2056Isup2.hkl

Supporting information. DOI: https://doi.org/10.1107/S2056989024001440/dx2056sup4.docx

Supporting information file. DOI: https://doi.org/10.1107/S2056989024001440/dx2056Isup4.cml

checkCIF report

Computing details top

2-(2-Azidophenyl)-3-oxo-3H-indole 1-oxide top

Crystal data top

C₁₄H₈N₄O₂	Z = 2
M_r = 264.24	F(000) = 272
Triclinic, P1	D_x = 1.513 Mg m⁻³
a = 7.166 (2) Å	Mo Kα radiation, λ = 0.71073 Å
b = 7.686 (3) Å	Cell parameters from 9975 reflections
c = 12.172 (4) Å	θ = 3.1–34.6°
α = 95.473 (16)°	µ = 0.11 mm⁻¹
β = 105.226 (12)°	T = 100 K
γ = 113.116 (13)°	Block, colourless
V = 579.9 (3) Å³	0.12 × 0.06 × 0.05 mm

Data collection top

Bruker D8 VENTURE Kappa Duo PHOTON II CPAD diffractometer	3946 reflections with I > 2σ(I)
φ and ω scans	R_int = 0.049
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	θ_max = 35.2°, θ_min = 3.0°
T_min = 0.626, T_max = 0.745	h = −11→11
45548 measured reflections	k = −12→12
4818 independent reflections	l = −19→19

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.042	H-atom parameters constrained
wR(F²) = 0.122	w = 1/[σ²(F_o²) + (0.066P)² + 0.1514P] where P = (F_o² + 2F_c²)/3
S = 1.05	(Δ/σ)_max < 0.001
4818 reflections	Δρ_max = 0.46 e Å⁻³
181 parameters	Δρ_min = −0.29 e Å⁻³
0 restraints

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	Occ. (<1)
O1	0.67828 (11)	−0.03978 (9)	0.35537 (6)	0.01840 (14)
O2	0.33615 (11)	0.29764 (9)	0.15423 (6)	0.01970 (14)
N4	1.05131 (16)	0.87935 (13)	0.27516 (9)	0.02787 (19)
N2	0.81071 (12)	0.56952 (10)	0.28504 (6)	0.01489 (14)
N3	0.93852 (12)	0.73575 (11)	0.28689 (7)	0.01669 (14)
C10	0.77636 (12)	0.53396 (11)	0.39246 (7)	0.01172 (14)
C9	0.64747 (12)	0.34085 (11)	0.39218 (7)	0.01194 (14)
C8	0.54989 (12)	0.18621 (11)	0.28650 (7)	0.01240 (14)
N1A	0.40687 (13)	0.17681 (11)	0.17988 (8)	0.01765 (16)	0.5
C14	0.34033 (13)	−0.00926 (12)	0.09961 (7)	0.01469 (15)
C2	0.20365 (14)	−0.08622 (14)	−0.01379 (8)	0.01915 (17)
H2	0.134768	−0.017372	−0.055149	0.023*
C3	0.17122 (15)	−0.27158 (15)	−0.06522 (8)	0.02109 (18)
H3	0.077902	−0.330058	−0.143374	0.025*
C11	0.86772 (13)	0.67870 (12)	0.49428 (7)	0.01393 (15)
H11	0.955317	0.808707	0.493893	0.017*
C12	0.83019 (14)	0.63213 (13)	0.59624 (7)	0.01570 (15)
H12	0.891796	0.730900	0.665580	0.019*
C13	0.70271 (14)	0.44142 (13)	0.59774 (7)	0.01594 (15)
H13	0.677285	0.410403	0.667753	0.019*
C15	0.61299 (13)	0.29688 (12)	0.49620 (7)	0.01451 (15)
H15	0.527337	0.166823	0.497471	0.017*
C17	0.57040 (12)	0.01171 (11)	0.27811 (7)	0.01585 (15)	0.5
C6	0.44015 (13)	−0.11001 (12)	0.16023 (7)	0.01356 (14)
C5	0.41071 (14)	−0.29159 (12)	0.11154 (8)	0.01623 (15)
H5	0.479954	−0.359268	0.153933	0.019*
C4	0.27263 (15)	−0.37139 (13)	−0.00430 (8)	0.01966 (17)
H4	0.247984	−0.496292	−0.041850	0.024*
C1B	0.40687 (13)	0.17681 (11)	0.17988 (8)	0.01765 (16)	0.5
N17A	0.57040 (12)	0.01171 (11)	0.27811 (7)	0.01585 (15)	0.5

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0195 (3)	0.0149 (3)	0.0197 (3)	0.0079 (2)	0.0042 (2)	0.0036 (2)
O2	0.0234 (3)	0.0138 (3)	0.0220 (3)	0.0095 (2)	0.0055 (2)	0.0039 (2)
N4	0.0328 (5)	0.0178 (4)	0.0343 (5)	0.0059 (3)	0.0205 (4)	0.0074 (3)
N2	0.0166 (3)	0.0121 (3)	0.0142 (3)	0.0040 (2)	0.0059 (2)	0.0031 (2)
N3	0.0184 (3)	0.0153 (3)	0.0178 (3)	0.0072 (3)	0.0084 (3)	0.0037 (2)
C10	0.0113 (3)	0.0120 (3)	0.0122 (3)	0.0057 (2)	0.0036 (2)	0.0023 (2)
C9	0.0112 (3)	0.0116 (3)	0.0128 (3)	0.0053 (3)	0.0033 (2)	0.0023 (2)
C8	0.0124 (3)	0.0099 (3)	0.0145 (3)	0.0043 (2)	0.0048 (3)	0.0024 (2)
N1A	0.0196 (4)	0.0103 (3)	0.0231 (4)	0.0038 (3)	0.0121 (3)	0.0015 (3)
C14	0.0162 (3)	0.0110 (3)	0.0183 (4)	0.0053 (3)	0.0088 (3)	0.0031 (3)
C2	0.0170 (4)	0.0261 (4)	0.0194 (4)	0.0118 (3)	0.0078 (3)	0.0116 (3)
C3	0.0172 (4)	0.0269 (4)	0.0129 (3)	0.0052 (3)	0.0033 (3)	0.0012 (3)
C11	0.0134 (3)	0.0120 (3)	0.0145 (3)	0.0053 (3)	0.0028 (3)	0.0004 (3)
C12	0.0165 (3)	0.0178 (4)	0.0130 (3)	0.0096 (3)	0.0028 (3)	0.0008 (3)
C13	0.0175 (4)	0.0202 (4)	0.0130 (3)	0.0104 (3)	0.0056 (3)	0.0044 (3)
C15	0.0148 (3)	0.0152 (3)	0.0153 (3)	0.0074 (3)	0.0057 (3)	0.0050 (3)
C17	0.0135 (3)	0.0138 (3)	0.0155 (3)	0.0015 (3)	0.0058 (3)	−0.0005 (2)
C6	0.0134 (3)	0.0117 (3)	0.0128 (3)	0.0029 (3)	0.0046 (3)	0.0010 (2)
C5	0.0187 (4)	0.0132 (3)	0.0191 (4)	0.0078 (3)	0.0077 (3)	0.0056 (3)
C4	0.0223 (4)	0.0133 (3)	0.0198 (4)	0.0041 (3)	0.0087 (3)	−0.0014 (3)
C1B	0.0196 (4)	0.0103 (3)	0.0231 (4)	0.0038 (3)	0.0121 (3)	0.0015 (3)
N17A	0.0135 (3)	0.0138 (3)	0.0155 (3)	0.0015 (3)	0.0058 (3)	−0.0005 (2)

Geometric parameters (Å, º) top

O1—C17	1.2523 (11)	C14—C1B	1.4767 (12)
O1—N17A	1.2523 (11)	C2—H2	0.9500
O2—N1A	1.2485 (11)	C2—C3	1.4033 (15)
O2—C1B	1.2485 (11)	C3—H3	0.9500
N4—N3	1.1323 (12)	C3—C4	1.3892 (14)
N2—N3	1.2396 (11)	C11—H11	0.9500
N2—C10	1.4245 (11)	C11—C12	1.3876 (12)
C10—C9	1.4061 (12)	C12—H12	0.9500
C10—C11	1.3933 (12)	C12—C13	1.3950 (13)
C9—C8	1.4628 (12)	C13—H13	0.9500
C9—C15	1.3996 (12)	C13—C15	1.3911 (12)
C8—N1A	1.4019 (13)	C15—H15	0.9500
C8—C17	1.4028 (12)	C17—C6	1.4697 (12)
C8—C1B	1.4019 (13)	C6—C5	1.3744 (12)
C8—N17A	1.4028 (12)	C6—N17A	1.4697 (12)
N1A—C14	1.4767 (12)	C5—H5	0.9500
C14—C2	1.3762 (13)	C5—C4	1.4033 (13)
C14—C6	1.3865 (12)	C4—H4	0.9500

N3—N2—C10	116.77 (7)	C12—C11—H11	120.1
N4—N3—N2	171.89 (9)	C11—C12—H12	119.7
C9—C10—N2	116.31 (7)	C11—C12—C13	120.52 (8)
C11—C10—N2	123.03 (8)	C13—C12—H12	119.7
C11—C10—C9	120.64 (8)	C12—C13—H13	120.2
C10—C9—C8	121.71 (7)	C15—C13—C12	119.67 (8)
C15—C9—C10	118.70 (7)	C15—C13—H13	120.2
C15—C9—C8	119.59 (7)	C9—C15—H15	119.6
N1A—C8—C9	126.97 (7)	C13—C15—C9	120.76 (8)
N1A—C8—C17	107.79 (7)	C13—C15—H15	119.6
C17—C8—C9	125.04 (7)	O1—C17—C8	127.91 (8)
C1B—C8—C9	126.97 (7)	O1—C17—C6	123.29 (8)
C1B—C8—N17A	107.79 (7)	C8—C17—C6	108.80 (7)
N17A—C8—C9	125.04 (7)	C14—C6—C17	107.50 (7)
O2—N1A—C8	127.81 (8)	C14—C6—N17A	107.50 (7)
O2—N1A—C14	123.50 (8)	C5—C6—C14	122.61 (8)
C8—N1A—C14	108.64 (7)	C5—C6—C17	129.89 (8)
C2—C14—N1A	131.01 (8)	C5—C6—N17A	129.89 (8)
C2—C14—C6	121.74 (8)	C6—C5—H5	121.9
C2—C14—C1B	131.01 (8)	C6—C5—C4	116.25 (8)
C6—C14—N1A	107.23 (8)	C4—C5—H5	121.9
C6—C14—C1B	107.23 (8)	C3—C4—C5	121.38 (8)
C14—C2—H2	121.7	C3—C4—H4	119.3
C14—C2—C3	116.59 (8)	C5—C4—H4	119.3
C3—C2—H2	121.7	O2—C1B—C8	127.81 (8)
C2—C3—H3	119.3	O2—C1B—C14	123.50 (8)
C4—C3—C2	121.42 (8)	C8—C1B—C14	108.64 (7)
C4—C3—H3	119.3	O1—N17A—C8	127.91 (8)
C10—C11—H11	120.1	O1—N17A—C6	123.29 (8)
C12—C11—C10	119.71 (8)	C8—N17A—C6	108.80 (7)

O1—C17—C6—C14	178.78 (8)	C14—C6—C5—C4	0.01 (12)
O1—C17—C6—C5	−0.58 (14)	C14—C6—N17A—O1	178.78 (8)
O2—N1A—C14—C2	2.51 (14)	C14—C6—N17A—C8	−0.88 (9)
O2—N1A—C14—C6	−176.07 (8)	C2—C14—C6—C17	−179.07 (7)
N2—C10—C9—C8	−1.48 (11)	C2—C14—C6—C5	0.35 (13)
N2—C10—C9—C15	178.39 (7)	C2—C14—C6—N17A	−179.07 (7)
N2—C10—C11—C12	−178.73 (7)	C2—C14—C1B—O2	2.51 (14)
N3—N2—C10—C9	−174.08 (7)	C2—C14—C1B—C8	−179.99 (9)
N3—N2—C10—C11	4.34 (12)	C2—C3—C4—C5	0.43 (14)
C10—C9—C8—N1A	−59.12 (12)	C11—C10—C9—C8	−179.94 (7)
C10—C9—C8—C17	126.65 (9)	C11—C10—C9—C15	−0.08 (11)
C10—C9—C8—C1B	−59.12 (12)	C11—C12—C13—C15	0.14 (13)
C10—C9—C8—N17A	126.65 (9)	C12—C13—C15—C9	−0.61 (12)
C10—C9—C15—C13	0.57 (12)	C15—C9—C8—N1A	121.02 (9)
C10—C11—C12—C13	0.35 (12)	C15—C9—C8—C17	−53.22 (11)
C9—C10—C11—C12	−0.38 (12)	C15—C9—C8—C1B	121.02 (9)
C9—C8—N1A—O2	0.35 (14)	C15—C9—C8—N17A	−53.22 (11)
C9—C8—N1A—C14	−177.02 (7)	C17—C8—N1A—O2	175.39 (8)
C9—C8—C17—O1	−2.70 (13)	C17—C8—N1A—C14	−1.97 (9)
C9—C8—C17—C6	176.94 (7)	C17—C6—C5—C4	179.29 (8)
C9—C8—C1B—O2	0.35 (14)	C6—C14—C2—C3	−0.31 (13)
C9—C8—C1B—C14	−177.02 (7)	C6—C14—C1B—O2	−176.07 (8)
C9—C8—N17A—O1	−2.70 (13)	C6—C14—C1B—C8	1.43 (9)
C9—C8—N17A—C6	176.94 (7)	C6—C5—C4—C3	−0.39 (13)
C8—C9—C15—C13	−179.56 (7)	C5—C6—N17A—O1	−0.58 (14)
C8—N1A—C14—C2	−179.99 (9)	C5—C6—N17A—C8	179.76 (8)
C8—N1A—C14—C6	1.43 (9)	C1B—C8—N17A—O1	−177.87 (8)
C8—C17—C6—C14	−0.88 (9)	C1B—C8—N17A—C6	1.78 (9)
C8—C17—C6—C5	179.76 (8)	C1B—C14—C2—C3	−178.72 (8)
N1A—C8—C17—O1	−177.87 (8)	C1B—C14—C6—C5	179.09 (7)
N1A—C8—C17—C6	1.78 (9)	C1B—C14—C6—N17A	−0.32 (9)
N1A—C14—C2—C3	−178.72 (8)	N17A—C8—C1B—O2	175.39 (8)
N1A—C14—C6—C17	−0.32 (9)	N17A—C8—C1B—C14	−1.97 (9)
N1A—C14—C6—C5	179.09 (7)	N17A—C6—C5—C4	179.29 (8)
C14—C2—C3—C4	−0.07 (13)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C5—H5···O2ⁱ	0.95	2.43	3.1077 (16)	128
C11—H11···O1ⁱⁱ	0.95	2.57	3.2327 (17)	127

Symmetry codes: (i) x, y−1, z; (ii) −x+2, −y+1, −z+1.

Covalent C=O/N⁺-O^- bond lengths (Å) in 2 and related structures top

Compound	C═O/N⁺—O^-	N⁺—O^-/C═O
SAWYAR	1.240 (4)	1.241 (4)
SAZQIU	1.253 (2)	1.243 (4)
2	1.252 (1)	1.248 (1)

Table 2. Weak hydrogen bond table of compound 2 top

No classical hydrogen bonds found. For C—H···acceptor interactions, see: Steiner, Th., (1996), Cryst. Rev., 6, 1-57 H-Bond classification [Jeffrey, G. A., Maluszynska, H. & Mitra, J., (1985), Int J. Biol. Macromol. 7, 336-348]

S.No	D-H···A	H···A (Å)	D···A (Å)	〈D-H···.A (°)
1	C5-H5···O2^(a)	2.43	3.1077 (16)	128
2	C11-H11···O1^(b)	2.57	3.2327 (17)	127

Symmetry codes: (i) x,-1+y,z (ii) 2-x,1-y,1-z .

Acknowledgements

CVR acknowledges SERB (CRG/2021/005729), New Delhi, India for funding this project. PD thanks DST-Inspire for the fellowship. ST thanks SERB for the Start-up Research Grant (SRG/2023/000209) and AESD&CIF (MLP0072), CSIR-CSMCRI for the infrastructure.

Funding information

Funding for this research was provided by: Science and Engineering Research Board (grant No. CRG/2021/005729 to Chepuri V. Ramana); Science and Engineering Research Board (grant No. SRG/2023/000209 to Srinu Tothadi).

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