Synthesis, structural studies and Hirshfeld surface analysis of 2-[(4-phenyl-1H-1,2,3-triazol-1-yl)methyl]pyridin-1-ium hexa­kis­(nitrato-κ2O,O′)thorate(IV)

Rangarajan, S.; Sheokand, S.; Blair, V.L.; Deacon, G.B.; Balakrishna, M.S.

doi:10.1107/S2056989024006352

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Volume 80| Part 8| August 2024|

https://doi.org/10.1107/S2056989024006352

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Synthesis, structural studies and Hirshfeld surface analysis of 2-[(4-phenyl-1H-1,2,3-triazol-1-yl)methyl]pyridin-1-ium hexakis(nitrato-κ²O,O′)thorate(IV)

Shalini Rangarajan,^a,^b Sonu Sheokand,^b Victoria L. Blair,^c Glen B. Deacon ^c and Maravanji S. Balakrishna ^b ^*

^aIITB-Monash Research Academy, Indian Institute of Technology Bombay, Mumbai 400076, India, ^bPhosphorus Laboratory, Department of Chemistry, Indian Institute of Technology, Bombay, Mumbai 400076, India, and ^cSchool of Chemistry, Monash University, Melbourne Clayton, Victoria 3800, Australia
^*Correspondence e-mail: krishna@chem.iitb.ac.in

Edited by J. M. Delgado, Universidad de Los Andes, Venezuela (Received 13 February 2024; accepted 28 June 2024; online 5 July 2024)

Reaction of thorium(IV) nitrate with 2-[(4-phenyl-1H-1,2,3-triazol-1-yl)methyl]pyridine (L) yielded (LH)₂[Th(NO₃)₆] or (C₁₄H₁₃N₄)₂[Th(NO₃)₆] (1), instead of the expected mixed-ligand complex [Th(NO₃)₄L₂], which was detected in the mass spectrum of 1. In the structure, the [Th(NO₃)₆]²⁻ anions display an icosahedral coordination geometry and are connected by LH⁺ cations through C—H⋯O hydrogen bonds. The LH⁺ cations interact via N—H⋯N hydrogen bonds. Hirshfeld surface analysis indicates that the most important interactions are O⋯H/H⋯O hydrogen-bonding interactions, which represent a 55.2% contribution.

Keywords: crystal structure; thorium complex; triazole framework; Hirshfeld surface analysis.

CCDC reference: 2366367

1. Chemical context

The nitrate ion with its small chelate or bite angle has a low steric footprint and is able to stabilize high coordination numbers. Thus 12-coordinate [Th(NO₃)₆]²⁻ has been isolated and structurally characterized with a variety of counter-cations such as: phen₂H⁺ (phen = 1,10-phenanthroline; Amani & Tayebee, 2013 ), bpyH₂²⁺ (bpy = 4,4′-bipyridine; Rammo et al., 1994 ) and NH₄⁺ (Spirlet et al., 1992 ), acetylpyridinium(thiosemicarbazone) (Abram et al., 1999 ), 2,2′-bipyridinium (Kumar & Tuck, 1984 ), [5,10,15,20-tetrakis(pyridinium-4-yl)porphyrin] (Mishra et al., 2019 ), 1-ethyl-3-methyl-1H-imidazol-3-ium (Kelley et al., 2020 ), among others (see Database survey section). Other interesting complexes are bis(oxonium dicyclohexano-18-crown-6) hexakis(nitrato-O,O′)-thorium(IV) where the counter-cation is H₃O⁺ (Wang et al., 1988 ) and bis[trinitrato-tetrakis(trimethylphosphine oxide)thorium(IV)] hexanitratothorium(IV) (Alcock et al., 1978 ) where both the anion and the cation are Th^IV complex ions.

Hexanitratothorate [Th(NO₃)₆]²⁻ and its analogous species are important in the speciation and separation of actinoid complexes in nitric acid (Zhang et al., 2017 ; Surbella et al., 2018 ; Takao et al., 2019 , 2020 ; Reilly et al., 2012 ; Matonic et al., 2002 ; Crawford et al., 2009 ; Rebizant et al., 1988 ).

Reaction of Th(NO₃)₄·5H₂O with 2-[(4-phenyl-1H-1,2,3-triazol-1-yl)methyl]pyridine (L) resulted in the formation of the nitrato complex (LH)₂[Th(NO₃)₆] (1), instead of [Th(NO₃)₄L₂], analogous to complexes of functionalized chelating pyridine-based ligands (Gephart et al., 2009 ; Xiao et al., 2014 ). The structure of complex 1 was established by X-ray crystallography, IR and mass spectroscopic data.

2. Structural commentary

Compound 1 crystallized in the monoclinic P2₁/n space group as a dianionic complex with two LH⁺ pyridinium counter-cations, as shown in Fig. 1. The thorium atom is located on an inversion centre and is coordinated by six chelating nitrate ions to assume a distorted icosahedral stereochemistry (Fig. 1c), similar to other reported hexanitratothorate(IV) complexes (Abram et al., 1999; Amani & Tayebee, 2013; Rammo et al., 1994; Spirlet et al., 1992). The Th—O bond lengths [2.5444 (13)–2.5830 (13) Å; Table 1] are similar to those reported, for example, for (H₂ATPSC)₂²⁺[Th(NO₃)₆]²⁻·4MeOH [2.553 (3)–2.580 (3) Å; HATPSC = 2-acetylpyridine thiosemicarbazone; Abram et al., 1999], (phen₂H⁺)₂²⁺[Th(NO₃)₆]²⁻·2H₂O [2.555 (7)–2.572 (6) Å; Amani & Tayebee, 2013], bpyH₂²⁺[Th(NO₃)₆]²⁻·2H₂O [2.567 (17)–2.599 (16) Å; Rammo et al., 1994] and (NH₄)₂²⁺[Th(NO₃)₆]²⁻ [2.545 (6)–2.608 (5) Å; Spirlet et al., 1992]. The pyridine nitrogen atom of the ligand is protonated. The pyridine N—C bond lengths in 1 are N4—C8 = 1.351 (2) Å and N4—C4 = 1.340 (3) Å [1.342 (5) Å and 1.340 (5) Å in L; Urankar et al., 2010 ] and the N4—H4 (pyridinium salt) bond distance is 0.862 (16) Å. In the triazole ring, the N—C distances are N1—C1 = 1.369 (2) Å and N3—C2 = 1.346 (2) Å [1.338 (5) and 1.353 (5) in L].

Table 1
Selected geometric parameters (Å, °)

Th1—O1	2.5830 (13)	N1—N2	1.314 (2)
Th1—O2	2.5621 (14)	N3—N2	1.343 (2)
Th1—O4	2.5583 (13)	N3—C2	1.346 (2)
Th1—O5	2.5547 (14)	N3—C3	1.461 (2)
Th1—O7	2.5444 (13)	N4—C4	1.340 (3)
Th1—O9	2.5827 (12)	N4—C8	1.351 (2)
N1—C1	1.369 (2)	N4—H4	0.862 (16)

O7—Th1—O4ⁱ	113.48 (4)	O9ⁱ—Th1—O1ⁱ	66.86 (4)
O7—Th1—O4	66.52 (4)	O2ⁱ—Th1—O9ⁱ	112.31 (4)
O7ⁱ—Th1—O9	130.23 (4)	O2ⁱ—Th1—O1ⁱ	49.70 (4)
O7—Th1—O9	49.77 (4)	O2ⁱ—Th1—O1	130.30 (4)
O7ⁱ—Th1—O1ⁱ	65.87 (4)	O2—Th1—O1	49.70 (4)
O7—Th1—O2ⁱ	69.99 (4)	O5ⁱ—Th1—O4	130.01 (4)
O7ⁱ—Th1—O5ⁱ	67.80 (4)	O5—Th1—O4	49.99 (4)
O4ⁱ—Th1—O9ⁱ	110.18 (4)	O5ⁱ—Th1—O9	66.29 (4)
O4ⁱ—Th1—O1ⁱ	112.94 (4)	O5ⁱ—Th1—O9ⁱ	113.71 (4)
O4ⁱ—Th1—O2ⁱ	113.64 (4)	O5ⁱ—Th1—O1ⁱ	69.63 (4)
O9—Th1—O9ⁱ	180.0	O5ⁱ—Th1—O2ⁱ	67.02 (4)
Symmetry code: (i) .

Figure 1
Molecular structure of 1: (a) Asymmetric unit of 1 showing the atom-labelling scheme, (b) perspective view of complex 1 and (c) coordination polyhedron around the Th^IV atom in 1. The hydrogen atoms are omitted for clarity except for the pyridinium hydrogen. Displacement ellipsoids are drawn at the 30% probability level.

3. Supramolecular features and Hirshfeld Surface Analysis

In the crystal, N—H⋯N and C—H⋯O hydrogen-bonding interactions are observed (Table 2). The packing also features C—H⋯π(ring) [C3—H3A⋯Cg1( $[{1\over 2}]$ + x, $[{3\over 2}]$ − y, $[{1\over 2}]$ − z) = 3.2029 (1) Å], π(ring)–π(ring) [Cg1⋯Cg2(1 − x, 2 − y, 2 − z) centroid–centroid distance = 3.6130 (11) Å] and O⋯C [N6—O3⋯Cg3( $[{3\over 2}]$ − x, $[{1\over 2}]$ + y, $[{3\over 2}]$ − z) = 3.7492 (18) Å] interactions where Cg1, Cg2 and Cg3 are the centroids of rings C9–C14, N1–N3/C1/C2, and N4/C4–C8, respectively. A C11⋯H3A(− $[{1\over 2}]$ + x, $[{3\over 2}]$ − y, − $[{1\over 2}]$ + z) short contact of 2.69 Å also occurs. Views of the packing of the cations and anions are displayed in Fig. 2a and 2b.

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N4—H4⋯N1ⁱⁱ	0.86 (3)	1.88 (3)	2.738 (3)	170 (3)
C2—H2⋯O8ⁱⁱⁱ	0.95	2.33	3.261 (3)	168
C7—H7⋯O5^iv	0.95	2.46	3.379 (3)	164
C13—H13⋯O4^v	0.95	2.46	3.377 (3)	163
N4—H4⋯N2ⁱⁱ	0.86	2.65 (3)	3.432 (3)	151
C10—H10⋯O8ⁱⁱⁱ	0.95	2.68	3.621 (3)	173
C5—H5⋯O2ⁱ	0.95	2.68	3.191 (2)	114
C7—H7⋯O2ⁱⁱⁱ	0.95	2.67	3.279 (3)	123
C7—H7⋯O9ⁱⁱⁱ	0.95	2.69	3.369 (2)	129
Symmetry codes: (i) ; (ii) ; (iii) $[-x+{\script{3\over 2}}, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (iv) $[x-{\script{1\over 2}}, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (v) $[-x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]$ .

Figure 2
(a) The packing of complex 1 showing the [C₁₄H₁₃N₄]⁺ cations in face-centered positions and [Th(NO₃)₆]²⁻ anions at the corners and in body-centered locations and (b) packing diagram showing intermolecular C—H⋯O hydrogen-bonding interactions (blue dotted lines).

In order to visualize the intermolecular interactions in the structure of 1, a Hirshfeld surface (HS) analysis was carried out (Spackman & Jayatilaka, 2009 ) and the associated two-dimensional fingerprint plots (McKinnon et al., 2007 ) were generated using CrystalExplorer 17.5 (Turner et al., 2017 ). A view of the three-dimensional Hirshfeld surface plotted over d_norm with the red, white and blue regions indicating contacts with distances shorter, equal and longer, respectively, than the van der Waals separations (Fig. 3). Interactions between donor and acceptor atoms are seen as red spots on the Hirshfeld surface mapped over d_norm (Fig. 3), corresponding to C2—H2⋯O8, N4—H4⋯N1, C7—H7⋯O5 and C13—H13⋯O4 hydrogen bonds. Fig. 4 shows the overall two-dimensional fingerprint plot and and those delineated into O⋯H/H⋯O (55.2%), H⋯H (11.2%), N⋯H/H⋯N (10.4%), C⋯H/H⋯C (7.5%), C⋯O/O⋯C (6.7%), O⋯O (3.3%), C⋯N/N⋯C (2.2%), C⋯C (1.8%), N⋯N (1.1%) and N⋯O/O⋯N (0.6%) interactions. The large number of O⋯H/H⋯O, N⋯H/H⋯H, C⋯H/H⋯C and H⋯H interactions suggest that hydrogen bonding and van der Waals interactions play a major role in the crystal packing of 1.

Figure 3
The three-dimensional Hirshfeld surface of the title compound 1, plotted over d_norm in the range. The hydrogen bonds are shown as dashed lines.

Figure 4
Hirshfeld surface of 1 mapped over d_norm (left images of each pair) with the corresponding two-dimensional fingerprint plots (right images of each pair). The d_i and d_e values are the closest internal and external distances (in Å) from given points on the Hirshfeld surface.

4. Database Survey

A search of the Cambridge Structural Database (CSD, Version 5.43, last update November 2022; Groom et al., 2016 ) for a 12-coordinate [Th(NO₃)₆]²⁻ moiety yielded several compounds related to the title compound, viz. CSD refcodes BEQVAU (Abram et al., 1999), FERKOD (Cheng et al., 2005 ), LEWNIM (Amani & Tayebee, 2013), YUWWAO (Rammo et al., 1994), GOBTAS (Wang et al., 1988), JOKRIN (Mishra et al., 2019), LUDMIJ (Kelley et al., 2020), NMPOTH (Alcock et al., 1978), TEQVIX, TEQVUJ, TEQWEU, TEQWIY, TEQWUK, TEQXIZ, TEQXOF and ZIYCER01 (Jin et al., 2017 ), UNAKAV (Goodgame et al., 2003 ) and ZEWBOS (Aparna et al., 1995 ). A search for lanthanide or actinide compounds with the ligand L did not return any hits.

5. Synthesis and crystallization

The ligand 2-[(4-phenyl-1H-1,2,3-triazol-1-yl)methyl]pyridine (L) was prepared as reported (Urankar et al., 2010). Th(NO₃)₄·5H₂O was purchased from a local source. Infrared spectra (4000–450 cm⁻¹) of solid samples were recorded on a Bruker Alpha II instrument using the attenuated total reflection (ATR) measurement mode. The mass spectrum was recorded using a Bruker Maxis Impact LC-q-TOF Mass Spectrometer.

A solution of 2-[(4-phenyl-1H-1,2,3-triazol-1-yl)methyl]pyridine (L) (24 mg, 0.10 mmol) in ethanol (10 ml) was layered over a solution of Th(NO₃)₄·5H₂O (57 mg, 0.10 mmol) in THF (10 ml). The reaction solution was slowly evaporated at room temperature to yield pale pink-coloured blocks of 1. Yield = 42 mg, 78%, dec. 541 K. FT–IR (ATR cm⁻¹) 2361 (s), 2352 (s), 2129 (w), 1632 (s), 1511 (vs, ν_asNO₂), 1472 (s), 1449 (s), 1269 (vs, ν_sNO₂), 1195 (s), 1087 (s), 1030 (vs, νNO), 806 (s), 767 (vs), 743 (vs), 708 (s), 694 (s). HRMS (m/z) calculated for C₂₈H₂₄N₁₁O₉Th [M –(2HNO₃ + NO₃⁻)] 890.2139; found 890.2139. Elemental analysis calculated (%) for C₂₈H₂₆N₁₄O₁₈Th (1078.63): C 31.18, H 2.43, N 18.18; found C 30.86, H 2.40, N 17.98. Owing to the poor solubility of compound 1 in organic solvents (CHCl₃, DMSO and THF), NMR characterization could not be carried out.

The IR spectrum of 1 showed absorptions due to the nitrate ligands at 1511, 1269 and 1030 cm⁻¹ (see Fig. S3 in the supporting information). The bands appearing at 1511 and 1269 cm⁻¹ correspond to the asymmetric (ν_as) and symmetric (ν_s) NO₂ stretching frequencies, respectively, while the band appearing at 1030 cm⁻¹ is assigned to ν(NO). These values correspond with those of chelating nitrate in [Th(NO₃)₄·tmu] (tmu = trimethylurea) at 1530, 1278 and 1023 cm⁻¹ (Amani & Tayebee, 2013; Nakamoto, 2008b ) and are in contrast with those of ionic nitrates (Na and K salts), which appear at 1405–1370 cm⁻¹ with ν(NO) only Raman active at 1068–1049 cm⁻¹ (Nakamoto, 2008a ). The high-resolution mass spectrum of 1 showed elimination of two molecules of HNO₃ and loss of the NO₃⁻ ion, leading to an m/z value of 820.2139 corresponding to [Th(NO₃)₃(C₁₄H₁₂N₄)₂]⁺, the formal ionization product of the [Th(NO₃)₄L₂] target (see Fig. S4).

6. Refinement

Crystal data, data collection and refinement details are given in Table 3. C-bound hydrogen atoms were placed in calculated positions (C—H = 0.95–0.99 Å) and refined using a riding model with U_iso(H) = 1.2U_eq(C). The N-bound H atom H4 was refined with the distance restraint N—H = 0.89±0.02 Å.

Table 3
Experimental details

Crystal data
Chemical formula	(C₁₄H₁₃N₄)₂[Th(NO₃)₆]
M_r	1078.67
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	150
a, b, c (Å)	14.5386 (3), 9.3464 (2), 15.4213 (4)
β (°)	117.846 (1)
V (Å³)	1852.85 (7)
Z	2
Radiation type	Mo Kα
μ (mm⁻¹)	4.12
Crystal size (mm)	0.09 × 0.07 × 0.06

Data collection
Diffractometer	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Krause et al., 2015 )
T_min, T_max	0.512, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections	27737, 4658, 3944
R_int	0.023
(sin θ/λ)_max (Å⁻¹)	0.673

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.015, 0.035, 1.05
No. of reflections	4658
No. of parameters	281
No. of restraints	1
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.72, −0.33
Computer programs: APEX4 and SAINT (Bruker, 2019 ), SHELXT2014/5 (Sheldrick, 2015a ), SHELXL2019/3 (Sheldrick, 2015b ) and OLEX2 (Dolomanov et al., 2009 ).

Supporting information

CCDC reference: 2366367

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2056989024006352/jw2006sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989024006352/jw2006Isup3.hkl

Spectroscopic data and structural graphics. DOI: https://doi.org/10.1107/S2056989024006352/jw2006sup5.docx

checkCIF report

Computing details top

2-[(4-Phenyl-1H-1,2,3-triazol-1-yl)methyl]pyridin-1-ium hexakis(nitrato-κ²O,O')thorate(IV) top

Crystal data top

(C₁₄H₁₃N₄)₂[Th(NO₃)₆]	F(000) = 1052
M_r = 1078.67	D_x = 1.933 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
a = 14.5386 (3) Å	Cell parameters from 9957 reflections
b = 9.3464 (2) Å	θ = 3.9–28.5°
c = 15.4213 (4) Å	µ = 4.12 mm⁻¹
β = 117.846 (1)°	T = 150 K
V = 1852.85 (7) Å³	Block, yellow
Z = 2	0.09 × 0.07 × 0.06 mm

Data collection top

Bruker APEXII CCD diffractometer	3944 reflections with I > 2σ(I)
φ and ω scans	R_int = 0.023
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	θ_max = 28.6°, θ_min = 2.7°
T_min = 0.512, T_max = 0.746	h = −19→19
27737 measured reflections	k = −12→12
4658 independent reflections	l = −20→20

Refinement top

Refinement on F²	Primary atom site location: dual
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.015	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.035	w = 1/[σ²(F_o²) + (0.0109P)² + 1.5954P] where P = (F_o² + 2F_c²)/3
S = 1.05	(Δ/σ)_max < 0.001
4658 reflections	Δρ_max = 0.72 e Å⁻³
281 parameters	Δρ_min = −0.33 e Å⁻³
1 restraint

Special details top

Experimental. A crystal of 1 suitable for X-ray analysis was mounted on a Cryoloop with a drop of Paratone oil and placed in the cold nitrogen stream of the Kryoflex attachment of the Bruker APEX-II CCD diffractometer. The raw data was reduced with SAINT V8.40A (Bruker, 2019). The absorption correction was done with SADABS2016/2 (Bruker, 2016/2). Structural solutions were obtained with SHELXT (Sheldrick, 2015a) and refined using full matrix least-squares against F² using SHELXL (Sheldrick, 2015b), in conjunction with the Olex2 (Dolomanov et al., 2009) graphical user interface.

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
Th1	0.500000	0.500000	0.500000	0.01543 (3)
O3	0.53542 (12)	0.85963 (17)	0.35224 (11)	0.0364 (3)
O8	0.82701 (10)	0.47216 (19)	0.64969 (12)	0.0398 (4)
O7	0.68122 (10)	0.54650 (15)	0.63986 (10)	0.0233 (3)
O4	0.50279 (10)	0.54161 (15)	0.66518 (10)	0.0258 (3)
O9	0.67896 (10)	0.40835 (15)	0.52678 (10)	0.0246 (3)
O1	0.60450 (10)	0.68989 (15)	0.46103 (10)	0.0252 (3)
O2	0.43750 (10)	0.71724 (15)	0.38557 (10)	0.0249 (3)
O5	0.50941 (10)	0.73336 (15)	0.59005 (10)	0.0257 (3)
N5	0.73268 (11)	0.47576 (17)	0.60683 (12)	0.0224 (3)
N3	0.62635 (11)	0.65844 (17)	1.02726 (11)	0.0214 (3)
N4	0.66816 (12)	0.40969 (17)	0.93013 (12)	0.0222 (3)
N1	0.48011 (12)	0.69191 (17)	1.02356 (12)	0.0223 (3)
N2	0.56554 (12)	0.61513 (17)	1.06624 (12)	0.0237 (3)
C9	0.40384 (13)	0.8878 (2)	0.89961 (13)	0.0203 (4)
N6	0.52628 (12)	0.75963 (17)	0.39768 (11)	0.0225 (3)
N7	0.50393 (13)	0.67864 (19)	0.66342 (12)	0.0273 (4)
C10	0.42192 (14)	0.9932 (2)	0.84549 (14)	0.0241 (4)
H10	0.487167	0.996946	0.845381	0.029*
O6	0.49717 (17)	0.7501 (2)	0.72531 (13)	0.0549 (5)
C2	0.58095 (14)	0.7630 (2)	0.96064 (13)	0.0228 (4)
H2	0.608517	0.811145	0.923638	0.027*
C1	0.48597 (13)	0.7850 (2)	0.95776 (13)	0.0198 (3)
C3	0.72825 (14)	0.5927 (2)	1.05898 (14)	0.0267 (4)
H3A	0.741548	0.523286	1.112040	0.032*
H3B	0.782565	0.667624	1.085923	0.032*
C11	0.34551 (15)	1.0927 (2)	0.79172 (14)	0.0266 (4)
H11	0.359140	1.165092	0.756012	0.032*
C14	0.30661 (15)	0.8835 (2)	0.89773 (15)	0.0272 (4)
H14	0.293076	0.812659	0.934452	0.033*
C4	0.67031 (14)	0.3342 (2)	0.85725 (14)	0.0252 (4)
H4A	0.620849	0.260215	0.826229	0.030*
C8	0.73579 (13)	0.51695 (19)	0.97626 (13)	0.0206 (4)
C5	0.74363 (14)	0.3631 (2)	0.82708 (14)	0.0248 (4)
H5	0.746028	0.308832	0.776090	0.030*
C6	0.81363 (15)	0.4723 (2)	0.87221 (15)	0.0258 (4)
H6	0.864548	0.494561	0.852061	0.031*
C7	0.80955 (14)	0.5499 (2)	0.94722 (15)	0.0238 (4)
H7	0.857548	0.625368	0.978375	0.029*
C12	0.24931 (16)	1.0868 (2)	0.78991 (14)	0.0290 (4)
H12	0.196841	1.154400	0.752611	0.035*
C13	0.23014 (16)	0.9816 (2)	0.84285 (16)	0.0317 (5)
H13	0.164176	0.976926	0.841424	0.038*
H4	0.6240 (17)	0.385 (3)	0.9501 (18)	0.043 (7)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Th1	0.01291 (4)	0.01679 (5)	0.01779 (4)	0.00037 (3)	0.00818 (3)	−0.00091 (4)
O3	0.0397 (8)	0.0323 (8)	0.0397 (8)	−0.0027 (7)	0.0206 (7)	0.0131 (7)
O8	0.0141 (6)	0.0579 (11)	0.0414 (9)	0.0031 (6)	0.0081 (6)	−0.0143 (8)
O7	0.0194 (6)	0.0259 (6)	0.0259 (7)	0.0010 (5)	0.0117 (5)	−0.0021 (6)
O4	0.0256 (7)	0.0276 (7)	0.0273 (7)	−0.0011 (5)	0.0151 (6)	−0.0020 (6)
O9	0.0204 (6)	0.0282 (7)	0.0254 (7)	0.0001 (5)	0.0109 (5)	−0.0041 (6)
O1	0.0202 (6)	0.0271 (7)	0.0280 (7)	−0.0004 (5)	0.0110 (5)	0.0012 (6)
O2	0.0198 (6)	0.0263 (7)	0.0290 (7)	0.0002 (5)	0.0116 (5)	0.0006 (6)
O5	0.0254 (7)	0.0249 (7)	0.0282 (7)	0.0002 (5)	0.0136 (6)	−0.0019 (6)
N5	0.0168 (7)	0.0258 (9)	0.0249 (8)	0.0007 (6)	0.0100 (6)	−0.0013 (6)
N3	0.0196 (7)	0.0250 (8)	0.0217 (7)	−0.0016 (6)	0.0113 (6)	−0.0010 (6)
N4	0.0189 (7)	0.0225 (8)	0.0260 (8)	−0.0010 (6)	0.0110 (6)	0.0054 (6)
N1	0.0233 (7)	0.0200 (8)	0.0274 (8)	−0.0044 (6)	0.0150 (7)	−0.0030 (6)
N2	0.0244 (8)	0.0230 (8)	0.0272 (8)	−0.0040 (6)	0.0149 (7)	−0.0021 (7)
C9	0.0209 (8)	0.0203 (9)	0.0211 (9)	−0.0029 (7)	0.0111 (7)	−0.0059 (7)
N6	0.0237 (7)	0.0220 (8)	0.0236 (8)	−0.0012 (6)	0.0126 (6)	−0.0001 (6)
N7	0.0270 (8)	0.0295 (9)	0.0271 (8)	−0.0018 (7)	0.0141 (7)	−0.0073 (7)
C10	0.0224 (8)	0.0267 (9)	0.0250 (9)	−0.0037 (8)	0.0125 (7)	−0.0042 (8)
O6	0.0897 (14)	0.0446 (10)	0.0450 (10)	−0.0058 (10)	0.0439 (10)	−0.0208 (8)
C2	0.0232 (8)	0.0257 (10)	0.0229 (9)	−0.0022 (7)	0.0136 (7)	0.0002 (7)
C1	0.0213 (8)	0.0189 (9)	0.0215 (8)	−0.0052 (7)	0.0121 (7)	−0.0055 (7)
C3	0.0199 (8)	0.0347 (11)	0.0239 (9)	0.0025 (8)	0.0090 (7)	0.0011 (8)
C11	0.0301 (10)	0.0274 (10)	0.0221 (9)	−0.0016 (8)	0.0120 (8)	−0.0006 (8)
C14	0.0260 (9)	0.0295 (10)	0.0327 (10)	0.0007 (8)	0.0193 (8)	0.0022 (8)
C4	0.0229 (9)	0.0201 (9)	0.0280 (10)	−0.0013 (7)	0.0082 (8)	0.0013 (8)
C8	0.0182 (8)	0.0207 (9)	0.0212 (8)	0.0026 (7)	0.0078 (7)	0.0045 (7)
C5	0.0272 (9)	0.0232 (9)	0.0239 (9)	0.0051 (7)	0.0119 (8)	0.0043 (8)
C6	0.0233 (9)	0.0271 (10)	0.0313 (10)	0.0033 (7)	0.0162 (8)	0.0060 (8)
C7	0.0201 (8)	0.0211 (8)	0.0309 (10)	−0.0015 (7)	0.0123 (8)	0.0018 (8)
C12	0.0291 (10)	0.0324 (11)	0.0242 (9)	0.0065 (8)	0.0112 (8)	−0.0004 (8)
C13	0.0259 (9)	0.0383 (12)	0.0363 (11)	0.0046 (8)	0.0190 (8)	0.0006 (9)

Geometric parameters (Å, º) top

Th1—O1	2.5830 (13)	N4—H4	0.862 (16)
Th1—O2	2.5621 (14)	C9—C10	1.393 (3)
Th1—O4ⁱ	2.5582 (13)	C9—C1	1.468 (3)
Th1—O4	2.5583 (13)	C9—C14	1.401 (2)
Th1—O5	2.5547 (14)	N7—O6	1.206 (2)
Th1—O7ⁱ	2.5444 (13)	C10—H10	0.9500
Th1—O7	2.5444 (13)	C10—C11	1.388 (3)
Th1—O9ⁱ	2.5827 (12)	C2—H2	0.9500
Th1—O9	2.5827 (12)	C2—C1	1.376 (2)
Th1—O1ⁱ	2.5830 (13)	C3—H3A	0.9900
Th1—O2ⁱ	2.5621 (13)	C3—H3B	0.9900
Th1—O5ⁱ	2.5547 (14)	C3—C8	1.507 (3)
O3—N6	1.212 (2)	C11—H11	0.9500
O8—N5	1.213 (2)	C11—C12	1.387 (3)
O7—N5	1.270 (2)	C14—H14	0.9500
O4—N7	1.281 (2)	C14—C13	1.383 (3)
O9—N5	1.277 (2)	C4—H4A	0.9500
O1—N6	1.279 (2)	C4—C5	1.374 (3)
O2—N6	1.2778 (19)	C8—C7	1.376 (2)
O5—N7	1.278 (2)	C5—H5	0.9500
N1—C1	1.369 (2)	C5—C6	1.379 (3)
N1—N2	1.314 (2)	C6—H6	0.9500
N3—N2	1.343 (2)	C6—C7	1.390 (3)
N3—C2	1.346 (2)	C7—H7	0.9500
N3—C3	1.461 (2)	C12—H12	0.9500
N4—C4	1.340 (3)	C12—C13	1.386 (3)
N4—C8	1.351 (2)	C13—H13	0.9500

O7ⁱ—Th1—O7	180.00 (6)	O8—N5—Th1	177.24 (14)
O7—Th1—O4ⁱ	113.48 (4)	O8—N5—O7	121.59 (16)
O7—Th1—O4	66.52 (4)	O8—N5—O9	122.56 (16)
O7ⁱ—Th1—O4ⁱ	66.52 (4)	O7—N5—Th1	57.08 (8)
O7ⁱ—Th1—O4	113.48 (4)	O7—N5—O9	115.85 (14)
O7ⁱ—Th1—O9	130.23 (4)	O9—N5—Th1	58.86 (8)
O7—Th1—O9ⁱ	130.23 (4)	N2—N3—C2	111.70 (15)
O7ⁱ—Th1—O9ⁱ	49.77 (4)	N2—N3—C3	120.00 (15)
O7—Th1—O9	49.77 (4)	C2—N3—C3	128.30 (16)
O7ⁱ—Th1—O1ⁱ	65.87 (4)	C4—N4—C8	122.43 (16)
O7—Th1—O1ⁱ	114.13 (4)	C4—N4—H4	118.1 (18)
O7ⁱ—Th1—O1	114.13 (4)	C8—N4—H4	119.4 (18)
O7—Th1—O1	65.87 (4)	N2—N1—C1	110.29 (15)
O7ⁱ—Th1—O2	69.99 (4)	N1—N2—N3	106.08 (15)
O7—Th1—O2	110.01 (4)	C10—C9—C1	120.12 (16)
O7—Th1—O2ⁱ	69.99 (4)	C10—C9—C14	118.62 (17)
O7ⁱ—Th1—O2ⁱ	110.01 (4)	C14—C9—C1	121.26 (17)
O7—Th1—O5	67.79 (4)	O3—N6—Th1	176.58 (13)
O7—Th1—O5ⁱ	112.20 (4)	O3—N6—O1	122.44 (15)
O7ⁱ—Th1—O5ⁱ	67.80 (4)	O3—N6—O2	122.05 (16)
O7ⁱ—Th1—O5	112.21 (4)	O1—N6—Th1	58.30 (8)
O4ⁱ—Th1—O4	180.0	O2—N6—Th1	57.35 (9)
O4ⁱ—Th1—O9ⁱ	110.18 (4)	O2—N6—O1	115.51 (15)
O4ⁱ—Th1—O9	69.82 (4)	O4—N7—Th1	57.75 (9)
O4—Th1—O9ⁱ	69.82 (4)	O5—N7—Th1	57.56 (9)
O4—Th1—O9	110.18 (4)	O5—N7—O4	115.19 (15)
O4ⁱ—Th1—O1ⁱ	112.94 (4)	O6—N7—Th1	174.91 (15)
O4—Th1—O1	112.94 (4)	O6—N7—O4	122.04 (18)
O4ⁱ—Th1—O1	67.06 (4)	O6—N7—O5	122.74 (18)
O4—Th1—O1ⁱ	67.06 (4)	C9—C10—H10	119.7
O4—Th1—O2	113.63 (4)	C11—C10—C9	120.61 (17)
O4ⁱ—Th1—O2ⁱ	113.64 (4)	C11—C10—H10	119.7
O4—Th1—O2ⁱ	66.36 (4)	N3—C2—H2	127.5
O4ⁱ—Th1—O2	66.37 (4)	N3—C2—C1	105.06 (16)
O9—Th1—O9ⁱ	180.0	C1—C2—H2	127.5
O9—Th1—O1	66.86 (4)	N1—C1—C9	123.68 (16)
O9ⁱ—Th1—O1	113.14 (4)	N1—C1—C2	106.87 (16)
O9ⁱ—Th1—O1ⁱ	66.86 (4)	C2—C1—C9	129.44 (17)
O9—Th1—O1ⁱ	113.14 (4)	N3—C3—H3A	109.2
O1ⁱ—Th1—O1	180.0	N3—C3—H3B	109.2
O2—Th1—O9ⁱ	67.69 (4)	N3—C3—C8	112.18 (15)
O2—Th1—O9	112.31 (4)	H3A—C3—H3B	107.9
O2ⁱ—Th1—O9ⁱ	112.31 (4)	C8—C3—H3A	109.2
O2ⁱ—Th1—O9	67.69 (4)	C8—C3—H3B	109.2
O2ⁱ—Th1—O1ⁱ	49.70 (4)	C10—C11—H11	119.9
O2ⁱ—Th1—O1	130.30 (4)	C12—C11—C10	120.24 (19)
O2—Th1—O1	49.70 (4)	C12—C11—H11	119.9
O2—Th1—O1ⁱ	130.30 (4)	C9—C14—H14	119.7
O2—Th1—O2ⁱ	180.0	C13—C14—C9	120.56 (19)
O5ⁱ—Th1—O4	130.01 (4)	C13—C14—H14	119.7
O5—Th1—O4	49.99 (4)	N4—C4—H4A	119.8
O5ⁱ—Th1—O4ⁱ	49.99 (4)	N4—C4—C5	120.40 (18)
O5—Th1—O4ⁱ	130.01 (4)	C5—C4—H4A	119.8
O5—Th1—O9ⁱ	66.29 (4)	N4—C8—C3	118.14 (16)
O5ⁱ—Th1—O9	66.29 (4)	N4—C8—C7	118.73 (17)
O5—Th1—O9	113.71 (4)	C7—C8—C3	123.11 (17)
O5ⁱ—Th1—O9ⁱ	113.71 (4)	C4—C5—H5	120.6
O5ⁱ—Th1—O1ⁱ	69.63 (4)	C4—C5—C6	118.76 (19)
O5—Th1—O1ⁱ	110.37 (4)	C6—C5—H5	120.6
O5ⁱ—Th1—O1	110.37 (4)	C5—C6—H6	120.1
O5—Th1—O1	69.63 (4)	C5—C6—C7	119.86 (18)
O5ⁱ—Th1—O2ⁱ	67.02 (4)	C7—C6—H6	120.1
O5—Th1—O2	67.02 (4)	C8—C7—C6	119.81 (18)
O5—Th1—O2ⁱ	112.98 (4)	C8—C7—H7	120.1
O5ⁱ—Th1—O2	112.98 (4)	C6—C7—H7	120.1
O5—Th1—O5ⁱ	180.0	C11—C12—H12	120.2
N5—O7—Th1	98.16 (10)	C13—C12—C11	119.64 (19)
N7—O4—Th1	97.20 (11)	C13—C12—H12	120.2
N5—O9—Th1	96.11 (9)	C14—C13—C12	120.31 (18)
N6—O1—Th1	96.79 (10)	C14—C13—H13	119.8
N6—O2—Th1	97.82 (10)	C12—C13—H13	119.8
N7—O5—Th1	97.47 (11)

Th1—O7—N5—O8	177.14 (16)	C9—C14—C13—C12	−0.8 (3)
Th1—O7—N5—O9	−3.46 (16)	C10—C9—C1—N1	170.29 (17)
Th1—O4—N7—O5	−3.92 (16)	C10—C9—C1—C2	−8.1 (3)
Th1—O4—N7—O6	173.99 (18)	C10—C9—C14—C13	0.3 (3)
Th1—O9—N5—O8	−177.22 (17)	C10—C11—C12—C13	0.6 (3)
Th1—O9—N5—O7	3.39 (16)	C2—N3—N2—N1	0.5 (2)
Th1—O1—N6—O3	−176.06 (16)	C2—N3—C3—C8	−62.5 (3)
Th1—O1—N6—O2	4.18 (15)	C1—N1—N2—N3	−0.4 (2)
Th1—O2—N6—O3	176.02 (15)	C1—C9—C10—C11	−178.78 (17)
Th1—O2—N6—O1	−4.23 (16)	C1—C9—C14—C13	179.74 (19)
Th1—O5—N7—O4	3.92 (16)	C3—N3—N2—N1	−179.63 (16)
Th1—O5—N7—O6	−173.96 (18)	C3—N3—C2—C1	179.72 (18)
N3—C2—C1—N1	0.2 (2)	C3—C8—C7—C6	178.06 (17)
N3—C2—C1—C9	178.82 (18)	C11—C12—C13—C14	0.4 (3)
N3—C3—C8—N4	−59.3 (2)	C14—C9—C10—C11	0.7 (3)
N3—C3—C8—C7	122.20 (19)	C14—C9—C1—N1	−9.2 (3)
N4—C4—C5—C6	−0.9 (3)	C14—C9—C1—C2	172.4 (2)
N4—C8—C7—C6	−0.5 (3)	C4—N4—C8—C3	−178.54 (16)
N2—N3—C2—C1	−0.4 (2)	C4—N4—C8—C7	0.0 (3)
N2—N3—C3—C8	117.63 (18)	C4—C5—C6—C7	0.5 (3)
N2—N1—C1—C9	−178.62 (16)	C8—N4—C4—C5	0.7 (3)
N2—N1—C1—C2	0.1 (2)	C5—C6—C7—C8	0.2 (3)
C9—C10—C11—C12	−1.1 (3)

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º) top

Cg1, Cg2 and Cg3 are the centroids of rings C9–C14, N1–N3/C1/C2, and N4/C4–C8, respectively.

D—H···A	D—H	H···A	D···A	D—H···A
N4—H4···N1ⁱⁱ	0.86 (3)	1.88 (3)	2.738 (3)	170 (3)
C2—H2···O8ⁱⁱⁱ	0.95	2.33	3.261 (3)	168
C7—H7···O5^iv	0.95	2.46	3.379 (3)	164
C13—H13···O4^v	0.95	2.46	3.377 (3)	163
N4—H4···N2ⁱⁱ	0.86	2.65 (3)	3.432 (3)	151
C10—H10···O8ⁱⁱⁱ	0.95	2.68	3.621 (3)	173
C5—H5···O2ⁱ	0.95	2.68	3.191 (2)	114
C7—H7···O2ⁱⁱⁱ	0.95	2.67	3.279 (3)	123
C7—H7···O9ⁱⁱⁱ	0.95	2.69	3.369 (2)	129

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

Acknowledgements

We are grateful to the Science & Engineering Research Board, New Delhi, for financial support of this work through grant CRG/2019/000040. We also thank the Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, for instrumentation facilities. SR gratefully acknowledges the Indian Institute of Technology Bombay-Monash Research Academy for financial support. SS thanks the UGC, New Delhi for JRF/SRF fellowships. We thank Dipanjan Mondal for X-ray crystallography data collection and integration.

References

Abram, U., Bonfada, E. & Schulz Lang, E. (1999). Acta Cryst. C55, 1479–1482. CrossRef CAS IUCr Journals Google Scholar
Alcock, N. W., Esperås, S., Bagnall, K. W. & Hsian-Yun, W. (1978). J. Chem. Soc. Dalton Trans. pp. 638–646. CrossRef Google Scholar
Amani, V. & Tayebee, R. (2013). Synth. React. Inorg. Met.-Org. Nano-Met. Chem. 43, 1118–1123. CrossRef CAS Google Scholar
Aparna, K., Krishnamurthy, S. S. & Nethaji, M. (1995). J. Chem. Soc. Dalton Trans. pp. 2991–2997. CrossRef Google Scholar
Bruker (2019). APEX4 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Cheng, J. Y., Dong, Y. B., Ma, J. P., Huang, R.-Q. & Smith, M. D. (2005). Inorg. Chem. Commun. 8, 6–8. CrossRef CAS Google Scholar
Crawford, M. J., Ellern, A., Karaghiosoff, K. & Mayer, P. (2009). Inorg. Chem. 48, 10877–10879. CrossRef PubMed CAS Google Scholar
Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339–341. Web of Science CrossRef CAS IUCr Journals Google Scholar
Gephart, R. T. III, Williams, N. J., Reibenspies, J. H., De Sousa, A. S. & Hancock, R. D. (2009). Inorg. Chem. 48, 8201–8209. CrossRef PubMed CAS Google Scholar
Goodgame, D. M., Menzer (née Smith), A. M., Menzer, S., White, A. J. & Williams, D. J. (2003). Inorg. Chim. Acta, 355, 314–321. Google Scholar
Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171–179. Web of Science CrossRef IUCr Journals Google Scholar
Jin, G. B., Lin, J., Estes, S. L., Skanthakumar, S. & Soderholm, L. (2017). J. Am. Chem. Soc. 139, 18003–18008. CrossRef CAS PubMed Google Scholar
Kelley, S. P., Smetana, V., Emerson, S. D., Mudring, A.-V. & Rogers, R. D. (2020). Chem. Commun. 56, 4232–4235. CrossRef CAS Google Scholar
Krause, L., Herbst-Irmer, R., Sheldrick, G. M. & Stalke, D. (2015). J. Appl. Cryst. 48, 3–10. Web of Science CSD CrossRef ICSD CAS IUCr Journals Google Scholar
Kumar, N. & Tuck, D. G. (1984). Can. J. Chem. 62, 1701–1704. CrossRef CAS Google Scholar
Matonic, J. H., Neu, M. P., Enriquez, A. E., Paine, R. T. & Scott, B. L. (2002). J. Chem. Soc. Dalton Trans. pp. 2328–2332. CrossRef Google Scholar
McKinnon, J. J., Jayatilaka, D. & Spackman, M. A. (2007). Chem. Commun. 3814–3816. Google Scholar
Mishra, M. K., Choudhary, H., Cordes, D. B., Kelley, S. P. & Rogers, R. D. (2019). Cryst. Growth Des. 19, 3529–3542. Web of Science CSD CrossRef CAS Google Scholar
Nakamoto, K. (2008a). Infrared and Raman Spectra of Inorganic and Coordination Compounds, Part A, 6th ed., pp. 149–354. Hoboken: Wiley. Google Scholar
Nakamoto, K. (2008b). Infrared and Raman Spectra of Inorganic and Coordination Compounds, Part B, 6th ed., pp. 1–273. Hoboken: Wiley. Google Scholar
Rammo, N. N., Hamid, K. R. & Ibrahim, T. K. (1994). J. Alloys Compd. 210, 319–324. CSD CrossRef CAS Web of Science Google Scholar
Rebizant, J., Apostolidis, C., Spirlet, M. R., Andreetti, G. D. & Kanellakopulos, B. (1988). Acta Cryst. C44, 2098–2101. CrossRef CAS IUCr Journals Google Scholar
Reilly, S. D., Scott, B. L. & Gaunt, A. J. (2012). Inorg. Chem. 51, 9165–9167. CrossRef CAS PubMed Google Scholar
Sheldrick, G. M. (2015a). Acta Cryst. A71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2015b). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Spackman, M. A. & Jayatilaka, D. (2009). CrystEngComm, 11, 19–32. Web of Science CrossRef CAS Google Scholar
Spirlet, M. R., Rebizant, J., Apostolidis, C., Kanellakopulos, B. & Dornberger, E. (1992). Acta Cryst. C48, 1161–1164. CrossRef CAS IUCr Journals Google Scholar
Surbella, R. G., Ducati, L. C., Autschbach, J., Pellegrini, K. L., McNamara, B. K., Schwantes, J. M. & Cahill, C. L. (2018). Chem. Commun. 54, 12014–12017. CrossRef CAS Google Scholar
Takao, K., Kazama, H., Ikeda, Y. & Tsushima, S. (2019). Angew. Chem. Int. Ed. 58, 240–243. CrossRef CAS Google Scholar
Takao, K., März, J., Matsuoka, M., Mashita, T., Kazama, H. & Tsushima, S. (2020). RSC Adv. 10, 6082–6087. CrossRef CAS PubMed Google Scholar
Turner, M. J., Mckinnon, J. J., Wolff, S. K., Grimwood, D. J., Spackman, P. R., Jayatilaka, D. & Spackman, M. A. (2017). CrystalExplorer17. The University of Western Australia. https://hirshfeldsurface.net Google Scholar
Urankar, D., Pinter, B., Pevec, A., De Proft, F., Turel, I. & Košmrlj, J. (2010). Inorg. Chem. 49, 4820–4829. CrossRef CAS PubMed Google Scholar
Wang, M., Wang, B., Zheng, P., Wang, W. & Lin, J. (1988). Acta Cryst. C44, 1913–1916. CrossRef CAS IUCr Journals Google Scholar
Xiao, C.-L., Wang, C.-Z., Yuan, L.-Y., Li, B., He, H., Wang, S., Zhao, Y.-L., Chai, Z.-F. & Shi, W.-Q. (2014). Inorg. Chem. 53, 1712–1720. CrossRef CAS PubMed Google Scholar
Zhang, Y., Yang, S., Yuan, X., Zhao, Y. & Tian, G. (2017). Chem. Commun. 53, 6421–6423. CrossRef CAS Google Scholar

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