(η6-Benzene)­chlorido­[(S)-2-(4-isopropyl-4,5-di­hydro­oxazol-2-yl)phenolato]ruthenium(II)

Kelani, M.T.; Muller, A.; Lammertsma, K.

doi:10.1107/S241431462400720X

metal-organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 9| Part 7| July 2024| x240720

https://doi.org/10.1107/S241431462400720X

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(η⁶-Benzene)chlorido[(S)-2-(4-isopropyl-4,5-dihydrooxazol-2-yl)phenolato]ruthenium(II)

Monsuru T. Kelani,^a ^* Alfred Muller ^a and Koop Lammertsma ^a

^aDepartment of Chemical Sciences, University of Johannesburg, Auckland Park, 2006, Johannesburg, South Africa
^*Correspondence e-mail: mansieurkelani@gmail.com

Edited by M. Zeller, Purdue University, USA (Received 15 July 2024; accepted 21 July 2024; online 26 July 2024)

The title compound, [Ru(C₁₂H₁₄NO₂)Cl(η⁶-C₆H₆)], exhibits a half-sandwich tripod stand structure and crystallizes in the orthorhombic space group P2₁2₁2₁. The arene group is η⁶ π-coordinated to the Ru atom with a centroid-to-metal distance of 1.6590 (5) Å, with the (S)-2-(4-isopropyl-4,5-dihydrooxazol-2-yl)phenolate chelate ligand forming a bite angle of 86.88 (19)° through its N and phenolate O atoms. The pseudo-octahedral geometry assumed by the complex is completed by a chloride ligand. The coordination of the optically pure bidentate ligand induces metal centered chirality onto the complex with a Flack parameter of −0.056.

Keywords: crystal structure; orthorhombic; ruthenium.

CCDC reference: 2372332

Structure description

Ruthenium complexes have profound applications in various studies relating to chemotherapeutics (Chan et al., 2017 ), catalysis (Chavarot et al., 2003 ; Hamelin et al., 2007 ), electrochemistry (Ryabov et al., 2005 ), and photochemistry (Huisman et al., 2016 ). The optically pure salicyloxazoline coordinating ligand of the complex is often employed as an auxiliary ligand towards the enantioselective synthesis of chiral-at-metal complexes. The approach relies on the leaving propensity of the benzene and the halo ligands for replacement in the octahedral geometry with another achiral ligand system as a strategy in most cases. The choice of the salicyloxazoline ligand is due to its reversible coordination upon acid protonation of its phenolate leaving the stereochemistry of the metal complex preserved (Gong et al., 2013 ). Thus, the use of the compound is extremely helpful in the synthesis of enantiomerically pure transition-metal complexes with metal-centred chirality (Gong et al., 2009 , 2010 ). The title compound (Fig. 1) features an optically pure bidentate salicyloxazoline and a chloride ligand within a pseudo-octahedral confinement of the three-legged stool while an arene ring occupying the seat of the stool completes the coordination sphere of the ruthenium(II) complex. The bite angle, 86.88 (19)°, of the bidentate ligand is comparable to those of its cymene analogues, 86.68° (Brunner et al., 1998 ), 88.29° (Davenport et al., 2004 ) and mesitylene analogue, 86.91° (Davenport et al., 2004) reported in the literature. The Ru forms bond lengths of 2.4176 (19), 2.063 (5) and 2.083 (6) Å to Cl1, O1 and N1, respectively. The crystal packing features weak C—H⋯X hydrogen bonding (X = O or Cl) in a manner in which each molecular unit is skewed like a satellite dish. Selected torsion angles are given in Table 1 and details of the hydrogen-bonding geometry in Table 2.

Table 1
Selected torsion angles (°)

O2—C1—C2—N1	−16.4 (7)	C8—C7—C12—O1	179.3 (6)
O2—C1—C2—C3	103.6 (6)	O2—C6—N1—Ru1	174.7 (4)
C6—C7—C8—C9	179.4 (6)	C3—C2—N1—Ru1	71.5 (7)
C10—C11—C12—O1	−179.3 (7)	C7—C6—O2—C1	174.8 (6)

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C8—H8⋯O2	0.93	2.38	2.725 (9)	102
C17—H17⋯Cl1ⁱ	0.93	2.80	3.440 (8)	127
C18—H18⋯O1ⁱ	0.93	2.54	3.405 (8)	156
Symmetry code: (i) .

Figure 1
ORTEP drawing of the title compound with 50% probability displacement ellipsoids.

Synthesis and crystallization

[η⁶-C₆H₆)₂RuCl₂]₂ (200 mg, 0.40 mmol, 1 eq), (S)-isopropyl-2-(2-hydroxyphenyl)oxazoline (174 mg, 0.84 mmol, 2 eq) and K₂CO₃ (122 mg, 0.88 mmol, 2 eq) were dissolved in acetonitrile and refluxed for 3 h with continuous stirring. The reaction mixture was cooled to room temperature and then concentrated in vacuo under reduced pressure to obtain a single enantiomer of the expected compound. The crude product was purified using column chromatography with silica gel to obtain an orange crystalline compound. Yield, 165 mg (46%, 0.4 mmol). ¹H NMR (DMSO-d₆) δ 7.24 (d, J = 7.5 Hz, 1H), 7.05 (t, J = 7.0 and 7.5 Hz, 1H), 6.62 (d, J = 8.5 Hz, 1H), 6.28 (t, J = 7.5 Hz, 1H), 5.71 (s, 6H), 4.84 (d, J = 9.0 Hz, 1H), 4.59 (dd, J = 3.0 and 8.0 Hz, 1H), 4.41 (t, J = 9.0 Hz, 1H), 2.56 (m, J = 6.0 and 7.5 Hz, 1H), 1.0 (d, J = 7.0 Hz, 3H), 0.68 (d, J = 6.5 Hz, 3H); ¹³C NMR (DMSO-d₆) δ 164.50, 133.10, 128.57, 128.26, 122.00, 112.40, 108.80, 83.33, 74.71, 67.07, 29.23, 19.12, 14.82; FTIR (neat, cm⁻¹) 3067, 1540, 1522, 1489, 1446, 1349, 1255, 1183, 1140, 1069, 826, 763; Elemental analysis calculated for C₁₈H₂₀ClNO₂Ru: C, 51.61; H, 4.81; N, 3.34. Found: C, 50.73; H, 4.95; N, 3.64.

Refinement

Details of the crystal data collection, solution and refinement are provided in Table 3.

Table 3
Experimental details

Crystal data
Chemical formula	[Ru(C₁₂H₁₄NO₂)Cl(C₆H₆)]
M_r	418.87
Crystal system, space group	Orthorhombic, P2₁2₁2₁
Temperature (K)	293
a, b, c (Å)	6.5669 (18), 9.414 (3), 27.570 (9)
V (Å³)	1704.5 (9)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	1.09
Crystal size (mm)	0.47 × 0.18 × 0.15

Data collection
Diffractometer	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Krause et al., 2015 )
T_min, T_max	0.662, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections	9005, 4074, 2937
R_int	0.053
(sin θ/λ)_max (Å⁻¹)	0.667

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.045, 0.089, 0.98
No. of reflections	4074
No. of parameters	210
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.66, −0.41
Absolute structure	Flack x determined using 934 quotients [(I⁺)−(I⁻)]/[(I⁺)+(I⁻)] (Parsons et al., 2013 )
Absolute structure parameter	−0.05 (6)
Computer programs: APEX2 and SAINT (Bruker, 2010 ), SHELXT (Sheldrick, 2015a ), SHELXL (Sheldrick, 2015b ), Mercury (Macrae et al.., 2020 ), publCIF (Westrip, 2010 ) and WinGX (Farrugia, 2012 ).

Structural data

CCDC reference: 2372332

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S241431462400720X/zl4075sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S241431462400720X/zl4075Isup4.hkl

checkCIF report

Computing details top

(η⁶-Benzene)chlorido[(S)-2-(4-isopropyl-4,5-dihydrooxazol-2-yl)phenolato]ruthenium(II) top

Crystal data top

[Ru(C₁₂H₁₄NO₂)Cl(C₆H₆)]	D_x = 1.632 Mg m⁻³
M_r = 418.87	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, P2₁2₁2₁	Cell parameters from 1424 reflections
a = 6.5669 (18) Å	θ = 2.6–22.4°
b = 9.414 (3) Å	µ = 1.09 mm⁻¹
c = 27.570 (9) Å	T = 293 K
V = 1704.5 (9) Å³	Plate, orange
Z = 4	0.47 × 0.18 × 0.15 mm
F(000) = 848

Data collection top

Bruker APEXII CCD diffractometer	2937 reflections with I > 2σ(I)
Detector resolution: φ and ω scans pixels mm^-1	R_int = 0.053
Bruker APEXII CCD scans	θ_max = 28.3°, θ_min = 2.3°
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	h = −8→6
T_min = 0.662, T_max = 0.746	k = −12→12
9005 measured reflections	l = −36→26
4074 independent reflections

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.045	H-atom parameters constrained
wR(F²) = 0.089	w = 1/[σ²(F_o²) + (0.0264P)²] where P = (F_o² + 2F_c²)/3
S = 0.98	(Δ/σ)_max = 0.002
4074 reflections	Δρ_max = 0.66 e Å⁻³
210 parameters	Δρ_min = −0.41 e Å⁻³
0 restraints	Absolute structure: Flack x determined using 934 quotients [(I⁺)-(I^-)]/[(I⁺)+(I^-)] (Parsons et al., 2013)
Primary atom site location: dual	Absolute structure parameter: −0.05 (6)

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. The structure solution and refinement were implemented using WinGX software program (Farrugia, 2012). The highest peak and deepest hole are 0.66 and -0.41 e Å^-3, respectively, which are 1.13 and 0.83 Å away from the ruthenium center. The refinement of the hydrogen atoms was performed isotropically in their idealized geometry while sitting and riding on their anisotropically refined parent atoms with U_iso = 1.2U_eq for the aromatic and methine protons, and U_iso = 1.5U_eq for the methyl protons.

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

	x	y	z	U_iso*/U_eq
C1	0.2589 (12)	1.2854 (9)	0.8188 (3)	0.047 (2)
H1A	0.379457	1.320678	0.835165	0.057*
H1B	0.267789	1.309492	0.784613	0.057*
C2	0.2375 (11)	1.1261 (8)	0.8256 (2)	0.0362 (17)
H2	0.364617	1.086811	0.838471	0.043*
C3	0.1761 (10)	1.0454 (9)	0.7791 (2)	0.0409 (19)
H3	0.137753	0.948622	0.788452	0.049*
C4	−0.0048 (18)	1.1122 (8)	0.7531 (2)	0.0508 (17)
H4A	0.030043	1.206761	0.743036	0.076*
H4B	−0.119213	1.115928	0.774774	0.076*
H4C	−0.039225	1.056171	0.725238	0.076*
C5	0.3629 (12)	1.0355 (12)	0.7454 (3)	0.070 (3)
H5A	0.333602	0.971968	0.719131	0.105*
H5B	0.477509	1.000471	0.763443	0.105*
H5C	0.393965	1.128034	0.732786	0.105*
C6	−0.0089 (13)	1.2403 (6)	0.86639 (19)	0.0312 (13)
C7	−0.1874 (9)	1.2786 (7)	0.8950 (2)	0.0316 (16)
C8	−0.2721 (11)	1.4153 (8)	0.8885 (2)	0.0394 (17)
H8	−0.212165	1.477639	0.866531	0.047*
C9	−0.4400 (11)	1.4573 (9)	0.9137 (3)	0.053 (2)
H9	−0.498466	1.545825	0.908180	0.064*
C10	−0.5219 (15)	1.3655 (9)	0.9478 (3)	0.056 (2)
H10	−0.632514	1.395362	0.966250	0.067*
C11	−0.4456 (10)	1.2333 (9)	0.9552 (3)	0.047 (2)
H11	−0.506447	1.174317	0.978042	0.057*
C12	−0.2755 (10)	1.1833 (8)	0.9288 (2)	0.0319 (16)
C13	0.2044 (11)	0.9128 (8)	0.9641 (2)	0.0424 (19)
H13	0.238607	0.979015	0.987744	0.051*
C14	0.0350 (12)	0.8234 (7)	0.9705 (2)	0.042 (2)
H14	−0.041486	0.830265	0.998837	0.050*
C15	−0.0200 (14)	0.7245 (7)	0.9352 (2)	0.0456 (18)
H15	−0.130235	0.664262	0.940233	0.055*
C16	0.0933 (11)	0.7167 (8)	0.8916 (3)	0.047 (2)
H16	0.052812	0.654450	0.867215	0.057*
C17	0.2667 (11)	0.8025 (8)	0.8847 (3)	0.0443 (19)
H17	0.343741	0.794385	0.856557	0.053*
C18	0.3229 (10)	0.9013 (8)	0.9212 (3)	0.043 (2)
H18	0.437009	0.958522	0.916953	0.052*
N1	0.0747 (7)	1.1175 (6)	0.86312 (18)	0.0311 (14)
O1	−0.2134 (7)	1.0558 (5)	0.93758 (15)	0.0381 (11)
O2	0.0756 (7)	1.3444 (5)	0.84022 (17)	0.0456 (14)
Cl1	−0.2594 (3)	0.8953 (2)	0.84198 (6)	0.0507 (5)
Ru1	0.00224 (9)	0.93480 (5)	0.90217 (2)	0.02858 (14)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.044 (5)	0.057 (5)	0.040 (4)	−0.015 (4)	0.012 (4)	0.001 (4)
C2	0.027 (4)	0.054 (5)	0.027 (3)	0.001 (4)	0.008 (3)	0.000 (3)
C3	0.040 (4)	0.047 (5)	0.036 (4)	0.006 (4)	0.010 (3)	−0.003 (4)
C4	0.052 (4)	0.061 (5)	0.039 (3)	−0.005 (8)	−0.013 (4)	−0.001 (3)
C5	0.061 (6)	0.106 (9)	0.044 (5)	0.030 (6)	0.012 (4)	−0.004 (5)
C6	0.041 (4)	0.028 (3)	0.025 (3)	−0.010 (5)	−0.001 (4)	−0.001 (2)
C7	0.027 (4)	0.037 (4)	0.030 (4)	0.000 (3)	0.000 (3)	−0.012 (3)
C8	0.045 (4)	0.038 (4)	0.036 (4)	0.003 (4)	−0.008 (3)	−0.004 (3)
C9	0.054 (6)	0.048 (5)	0.058 (5)	0.017 (4)	−0.015 (4)	−0.021 (4)
C10	0.045 (5)	0.066 (5)	0.055 (4)	0.011 (6)	0.008 (5)	−0.026 (4)
C11	0.043 (6)	0.049 (5)	0.051 (4)	0.002 (4)	0.014 (3)	−0.017 (4)
C12	0.029 (4)	0.038 (4)	0.029 (3)	−0.001 (3)	0.003 (3)	−0.013 (3)
C13	0.040 (4)	0.047 (5)	0.040 (4)	−0.002 (4)	−0.014 (3)	0.008 (4)
C14	0.050 (6)	0.041 (4)	0.035 (3)	−0.003 (4)	0.007 (4)	0.012 (3)
C15	0.046 (5)	0.035 (4)	0.056 (4)	−0.010 (5)	0.008 (5)	0.013 (3)
C16	0.052 (5)	0.035 (4)	0.056 (5)	0.001 (4)	0.001 (4)	−0.003 (4)
C17	0.029 (4)	0.045 (5)	0.059 (5)	0.008 (4)	0.009 (4)	0.001 (4)
C18	0.027 (4)	0.044 (5)	0.059 (5)	0.001 (3)	−0.004 (3)	0.010 (4)
N1	0.019 (3)	0.047 (4)	0.028 (3)	−0.008 (3)	0.005 (2)	0.001 (3)
O1	0.039 (3)	0.037 (3)	0.039 (2)	0.001 (3)	0.017 (2)	−0.002 (2)
O2	0.049 (3)	0.043 (3)	0.046 (3)	−0.007 (2)	0.012 (2)	0.008 (2)
Cl1	0.0276 (10)	0.0772 (16)	0.0475 (10)	−0.0096 (10)	−0.0033 (8)	−0.0106 (10)
Ru1	0.0237 (2)	0.0325 (2)	0.0295 (2)	−0.0020 (4)	0.0034 (3)	−0.0008 (2)

Geometric parameters (Å, º) top

C1—O2	1.452 (8)	C9—C10	1.386 (11)
C1—C2	1.519 (10)	C9—H9	0.9300
C1—H1A	0.9700	C10—C11	1.357 (11)
C1—H1B	0.9700	C10—H10	0.9300
C2—N1	1.490 (7)	C11—C12	1.414 (9)
C2—C3	1.542 (9)	C11—H11	0.9300
C2—H2	0.9800	C12—O1	1.291 (8)
C3—C4	1.523 (12)	C13—C14	1.406 (9)
C3—C5	1.541 (9)	C13—C18	1.420 (9)
C3—H3	0.9800	C13—H13	0.9300
C4—H4A	0.9600	C14—C15	1.396 (9)
C4—H4B	0.9600	C14—H14	0.9300
C4—H4C	0.9600	C15—C16	1.416 (10)
C5—H5A	0.9600	C15—H15	0.9300
C5—H5B	0.9600	C16—C17	1.409 (10)
C5—H5C	0.9600	C16—H16	0.9300
C6—N1	1.282 (8)	C17—C18	1.418 (10)
C6—O2	1.338 (7)	C17—H17	0.9300
C6—C7	1.458 (10)	C18—H18	0.9300
C7—C8	1.413 (9)	N1—Ru1	2.084 (6)
C7—C12	1.418 (9)	O1—Ru1	2.063 (5)
C8—C9	1.363 (9)	Cl1—Ru1	2.4176 (19)
C8—H8	0.9300

O2—C1—C2	104.5 (6)	C8—C9—C10	118.6 (8)
O2—C1—H1A	110.9	C8—C9—H9	120.7
C2—C1—H1A	110.9	C10—C9—H9	120.7
O2—C1—H1B	110.9	C11—C10—C9	122.0 (8)
C2—C1—H1B	110.9	C11—C10—H10	119.0
H1A—C1—H1B	108.9	C9—C10—H10	119.0
N1—C2—C1	101.9 (6)	C10—C11—C12	121.4 (8)
N1—C2—C3	111.3 (5)	C10—C11—H11	119.3
C1—C2—C3	114.1 (6)	C12—C11—H11	119.3
N1—C2—H2	109.8	O1—C12—C11	117.5 (7)
C1—C2—H2	109.8	O1—C12—C7	125.7 (6)
C3—C2—H2	109.8	C11—C12—C7	116.7 (7)
C4—C3—C5	111.3 (6)	C14—C13—C18	119.6 (7)
C4—C3—C2	113.0 (6)	C14—C13—H13	120.2
C5—C3—C2	108.8 (6)	C18—C13—H13	120.2
C4—C3—H3	107.9	C15—C14—C13	121.0 (7)
C5—C3—H3	107.9	C15—C14—H14	119.5
C2—C3—H3	107.9	C13—C14—H14	119.5
C3—C4—H4A	109.5	C14—C15—C16	119.5 (7)
C3—C4—H4B	109.5	C14—C15—H15	120.3
H4A—C4—H4B	109.5	C16—C15—H15	120.3
C3—C4—H4C	109.5	C17—C16—C15	120.6 (7)
H4A—C4—H4C	109.5	C17—C16—H16	119.7
H4B—C4—H4C	109.5	C15—C16—H16	119.7
C3—C5—H5A	109.5	C16—C17—C18	119.5 (7)
C3—C5—H5B	109.5	C16—C17—H17	120.3
H5A—C5—H5B	109.5	C18—C17—H17	120.3
C3—C5—H5C	109.5	C17—C18—C13	119.8 (7)
H5A—C5—H5C	109.5	C17—C18—H18	120.1
H5B—C5—H5C	109.5	C13—C18—H18	120.1
N1—C6—O2	116.4 (7)	C6—N1—C2	107.9 (6)
N1—C6—C7	127.3 (6)	C6—N1—Ru1	127.6 (4)
O2—C6—C7	116.3 (6)	C2—N1—Ru1	124.5 (5)
C8—C7—C12	120.0 (6)	C12—O1—Ru1	129.9 (4)
C8—C7—C6	118.3 (6)	C6—O2—C1	106.5 (6)
C12—C7—C6	121.8 (6)	O1—Ru1—N1	86.9 (2)
C9—C8—C7	121.2 (7)	O1—Ru1—Cl1	85.52 (14)
C9—C8—H8	119.4	N1—Ru1—Cl1	86.26 (15)
C7—C8—H8	119.4

O2—C1—C2—N1	−16.4 (7)	C6—C7—C12—C11	178.7 (6)
O2—C1—C2—C3	103.6 (6)	C18—C13—C14—C15	−0.7 (11)
N1—C2—C3—C4	65.7 (8)	C13—C14—C15—C16	−1.7 (11)
C1—C2—C3—C4	−48.8 (9)	C14—C15—C16—C17	3.3 (11)
N1—C2—C3—C5	−170.2 (6)	C15—C16—C17—C18	−2.5 (11)
C1—C2—C3—C5	75.2 (8)	C16—C17—C18—C13	0.1 (11)
N1—C6—C7—C8	−171.5 (7)	C14—C13—C18—C17	1.5 (11)
O2—C6—C7—C8	7.7 (9)	O2—C6—N1—C2	−5.5 (8)
N1—C6—C7—C12	8.9 (11)	C7—C6—N1—C2	173.7 (6)
O2—C6—C7—C12	−172.0 (6)	O2—C6—N1—Ru1	174.7 (4)
C12—C7—C8—C9	−0.9 (10)	C7—C6—N1—Ru1	−6.2 (10)
C6—C7—C8—C9	179.4 (6)	C1—C2—N1—C6	13.7 (7)
C7—C8—C9—C10	2.9 (11)	C3—C2—N1—C6	−108.3 (7)
C8—C9—C10—C11	−3.0 (13)	C1—C2—N1—Ru1	−166.5 (4)
C9—C10—C11—C12	1.1 (13)	C3—C2—N1—Ru1	71.5 (7)
C10—C11—C12—O1	−179.3 (7)	C11—C12—O1—Ru1	171.7 (4)
C10—C11—C12—C7	0.9 (10)	C7—C12—O1—Ru1	−8.6 (10)
C8—C7—C12—O1	179.3 (6)	N1—C6—O2—C1	−5.9 (8)
C6—C7—C12—O1	−1.1 (10)	C7—C6—O2—C1	174.8 (6)
C8—C7—C12—C11	−1.0 (9)	C2—C1—O2—C6	14.2 (7)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C8—H8···O2	0.93	2.38	2.725 (9)	102
C17—H17···Cl1ⁱ	0.93	2.80	3.440 (8)	127
C18—H18···O1ⁱ	0.93	2.54	3.405 (8)	156

Symmetry code: (i) x+1, y, z.

Acknowledgements

We appreciate Dr B. Vatsha at the Department of Chemical Sciences, University of Johannesburg, for the collection of data.

Funding information

Funding for this research was provided by: National Research Foundation (grant No. 120842).

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