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Acta Crystallogr Sect E Struct Rep Online. 2009 November 1; 65(Pt 11): o2640.
Published online 2009 October 3. doi:  10.1107/S1600536809039130
PMCID: PMC2971053

N-(2-Bromo­benz­yl)-N′-(2-pyrid­yl)benzene-1,2-diamine

Abstract

In the title compound, C18H16BrN3, mol­ecules are linked into dimers by co-operative inter­molecular N—H(...)N hydrogen bonding. Only one N—H group is involved in hydrogen bonding. The planes of the pyridine and bromo­phenyl rings are twisted by 61.49 (3) and 79.11 (8)°, respectively, from the plane of the central phenyl ring.

Related literature

The title compound was isolated as part of a project to further investigate the chemistry of chalcogen–carbene compounds (Dutton et al., 2007 [triangle]). The stability of imidazole-based carbenes depends very much on the nature of the substituents attached to the imidazole nitrogen atoms, see: Huynh et al. (2006 [triangle]); Kuhn et al. (1993 [triangle]). For bond lengths in analogous compounds, see: Albéniz et al. (2002 [triangle]); Denk et al. (2001 [triangle]). For details of the synthesis, see: Hahn et al. (2007 [triangle]).

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Object name is e-65-o2640-scheme1.jpg

Experimental

Crystal data

  • C18H16BrN3
  • M r = 354.25
  • Triclinic, An external file that holds a picture, illustration, etc.
Object name is e-65-o2640-efi1.jpg
  • a = 7.9429 (5) Å
  • b = 9.5314 (8) Å
  • c = 11.0606 (8) Å
  • α = 98.741 (6)°
  • β = 90.727 (6)°
  • γ = 103.581 (6)°
  • V = 803.48 (10) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 2.56 mm−1
  • T = 200 K
  • 0.51 × 0.43 × 0.16 mm

Data collection

  • Oxford Diffraction Gemini R diffractometer
  • Absorption correction: multi-scan (CrysAlis Pro; Oxford Diffraction, 2009 [triangle]) T min = 0.553, T max = 1.000
  • 8461 measured reflections
  • 3249 independent reflections
  • 2038 reflections with I > 2σ(I)
  • R int = 0.042

Refinement

  • R[F 2 > 2σ(F 2)] = 0.039
  • wR(F 2) = 0.092
  • S = 0.89
  • 3249 reflections
  • 199 parameters
  • H-atom parameters constrained
  • Δρmax = 0.59 e Å−3
  • Δρmin = −0.48 e Å−3

Data collection: CrysAlis Pro (Oxford Diffraction, 2009 [triangle]); cell refinement: CrysAlis Pro; data reduction: CrysAlis Pro; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: SHELXTL (Sheldrick, 2008 [triangle]); software used to prepare material for publication: SHELXTL.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809039130/bt5071sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809039130/bt5071Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

HSB is grateful to the Department of Science and Technology (DST) for the award of a Ramanna Fellowship. STM thanks the CSIR for a JRF/SRF fellowship. RJB wishes to acknowledge the NSF–MRI program (grant CHE-0619278) for funds to purchase the diffractometer.

supplementary crystallographic information

Comment

The structure of the title compound, C18H16BrN3, (2), is shown below. Dimensions are available in the archived CIF.

Carbene compounds sometimes show unpredictable reactivity patterns and are subject to hydrolysis (Denk et al. 2001; Albéniz et al., 2002). The stability of imidazole based carbenes depends very much on the nature of the substituents attached to the imidazole nitrogen atoms (Hahn et al., 2007; Huynh et al. 2006).

The title compound was isolated as part of a project to further investigate the chemistry of chalcogen-carbene compounds (Dutton et al., 2007), in particular tellurium-carbene chemistry with pyridine as a substituent on the nitrogen of the benzimidazole ring. However, in contrast with electron donating substituents such as n-butyl, and i-propyl, which lead to tellurium carbene formation, electron withdrawing groups such as phenyl and pyridyl result in hydrolysed products, such as the title compound. A repeated attempt to synthesize the pyridine substituted tellurone compound gave the title compound whose structure is reported here.

In (2) the bonds are in the usual ranges found for analogous compounds (Albéniz et al. 2002; Denk et al. 2001)).

The molecules are linked into dimers by cooperative intermolecular N—H···N hydrogen bonding. The two N—H moieties adopt different conformations with respect to the phenyl ring to which they are both attached. N1—H is only twisted by 18.0 (2)° from this plane. As a result of this coplanarity the hydrogen attached to N1 does not form any hydrogen bonds. N2—H, however, is twisted by 51.8 (2)° from this plane so as to participate in the intermolecular hydrogen bonding mentioned above. The planes of the pyridine and bromo-phenyl rings are twisted by 61.49 (3)° and 79.11 (8)° from the plane of the central phenyl ring.

The cleavage of carbene carbon from benzimidazole ring in the title compound may be due to: 1) destabilization of C=Te by the electron withdrawing group present on the benzimidazolium nitrogen, 2) crowding near to the carbene carbon. The exact mechanism is under investigation. This structural study has confirmed the cleavage of the carbene carbon.

Experimental

In all cases, the starting benzylimidazoylium salt, 1, shown in scheme (1) was prepared using standard methods (Hahn et al. 2007). With the appropriate salt, the title compound could be made by three different methods: (a). In a round bottom flask the benzylimidazoylium salt 1 (1.0 mmol) was taken in THF (40 mL) under nitrogen atmosphere and of n-BuLi (2.0 mmol) was added at -78 °C, reaction mixture was stirred for 1-2 h. Then Te powder was added to the reaction mixture at room temperature, and stirred for 8-10 h. After completion of reaction, water (30 mL) was added and extracted with dichloromethane, dried over Na2SO4 and evaporated. The residue obtained was dissolved in toluene and small amount of petroleum ether was added to separate the residue from the solution. The solution was filtered, evaporated and the residue was dissolved in diethyl ether and a small amount of petroleum ether (60-80 °C) to afford the pure colorless product in 45% yield.

(b) The benzylimidazoylium salt 1 (1.0 mmol) was added to a brown solution of Na2Te2 (2.0 mmol) at room temperature under nitrogen atmosphere and the reaction mixture was stirred for 6-10 h at room temperature. Then KOtBu (1.0 mmol) was added to the reaction mixture and stirred further for 5-7 h. After completion of reaction, the reaction was quenched by adding water (50 mL), and extracted with dichloromethane, dried over Na2SO4, and evaporated. The residue obtained was dissolved in toluene and small amount of petroleum ether was added to separate the residue from the solution. The solution was filtered and evaporated; the residue was dissolved in diethyl ether and a small amount of petroleum ether (60-80 °C) to afford the pure crystalline product.

(c) In a round bottom flask the benzylimidazoylium salt 1 (1.0 mmol) was taken in THF (40 mL) under nitrogen atmosphere and Te metal powder (1.0 mmol) was added, then KOtBu (2.0 mmol) was added to the reaction mixture at -20 °C. The reaction mixture was stirred for 5-6 h. Then the reaction was quenched by adding water (50 mL), and extracted with dichloromethane, dried over Na2SO4, and evaporated. The residue obtained was dissolved in toluene and some petroleum ether was added to separate the residue from the solution. The solution was filtered and evaporated; the residue was dissolved in diethyl ether and small amount of petroleum ether (60-80 °C) to afford the pure product.

Mp 156-158 °C. 1H NMR (400 MHz, CDCl3): δ (ppm) 8.15 (m, 1H), 7.54 (dd, J = 7.6 Hz, J = 1.2 Hz, 1H), 7.43 (m, 1H), 7.32 (m, 1H), 7.23 (m, 2H), 7.11 (m, 2H), 6.71 (m, 2H), 6.61 (dd, J = 8 Hz, J = 1.2 Hz, 1H), 6.40 (m, 1H), 6.15 (s, 1H), 4.83 (d, J = 5.6 Hz, 1H), 4.41 (d, J = 6 Hz, 2H). 13C NMR (100 MHz, CDCl3): δ (ppm) 158.4, 148.4, 144.5, 138.1, 132.9, 128.9, 128.8, 127.8, 127.6, 127.4, 125.7, 123.4, 117.7, 114.6, 111.7, 107.4, 48.2. MS: m/z 353 [M]+, 355 [M+2]+ . Anal. Calcd. for C18H16BrN3 (%): C, 61.03; H, 4.55; N, 11.86. Found: C, 60.85; H, 4.55; N, 11.40.

Refinement

H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms with C—H distances of 0.95 and 0.99 Å Uiso(H) = 1.2Ueq(C). The H attached to N was idealized with a distance of 0.88 Å.

Figures

Fig. 1.
The molecular structure of C18H16BrN3 the showing the atom numbering scheme and 50% probability displacement ellipsoids.
Fig. 2.
The molecular packing for C18H16BrN3 viewed down the a axis. The hydrogen bonding between N—H···N is shown by dashed lines.
Fig. 3.
The formation of the title compound.

Crystal data

C18H16BrN3Z = 2
Mr = 354.25F(000) = 360
Triclinic, P1Dx = 1.464 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 7.9429 (5) ÅCell parameters from 3047 reflections
b = 9.5314 (8) Åθ = 4.7–34.8°
c = 11.0606 (8) ŵ = 2.56 mm1
α = 98.741 (6)°T = 200 K
β = 90.727 (6)°Irregular plate, colorless
γ = 103.581 (6)°0.51 × 0.43 × 0.16 mm
V = 803.48 (10) Å3

Data collection

Oxford Diffraction Gemini R diffractometer3249 independent reflections
Radiation source: Enhance (Mo) X-ray Source2038 reflections with I > 2σ(I)
graphiteRint = 0.042
Detector resolution: 10.5081 pixels mm-1θmax = 26.4°, θmin = 4.7°
ω scansh = −9→9
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009)k = −11→11
Tmin = 0.553, Tmax = 1.000l = −13→13
8461 measured reflections

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.039Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.092H-atom parameters constrained
S = 0.89w = 1/[σ2(Fo2) + (0.052P)2] where P = (Fo2 + 2Fc2)/3
3249 reflections(Δ/σ)max = 0.001
199 parametersΔρmax = 0.59 e Å3
0 restraintsΔρmin = −0.48 e Å3

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

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

xyzUiso*/Ueq
Br0.83487 (5)0.00876 (4)0.69232 (3)0.05856 (16)
N10.7358 (3)0.1251 (3)0.31573 (19)0.0433 (6)
H1A0.67760.05420.25950.052*
N20.5888 (3)0.1863 (3)0.1091 (2)0.0405 (6)
H2A0.61180.10080.08490.049*
N30.3381 (3)0.0980 (2)−0.01114 (19)0.0326 (5)
C10.7931 (4)0.2636 (3)0.2846 (2)0.0351 (7)
C20.7198 (4)0.2970 (3)0.1804 (2)0.0348 (7)
C30.7745 (4)0.4348 (3)0.1484 (3)0.0408 (7)
H3A0.72400.45630.07720.049*
C40.9013 (4)0.5417 (4)0.2185 (3)0.0477 (8)
H4A0.93530.63700.19750.057*
C50.9773 (4)0.5079 (4)0.3189 (3)0.0481 (9)
H5A1.06690.57990.36610.058*
C60.9258 (4)0.3714 (3)0.3522 (2)0.0467 (8)
H6A0.98070.35010.42170.056*
C1A0.7671 (4)0.0915 (3)0.4359 (2)0.0386 (7)
H1AA0.89300.12490.45750.046*
H1AB0.7348−0.01600.43170.046*
C2A0.6705 (3)0.1589 (3)0.5388 (2)0.0342 (7)
C3A0.6902 (4)0.1324 (3)0.6583 (2)0.0384 (7)
C4A0.6043 (4)0.1895 (4)0.7542 (3)0.0487 (9)
H4AA0.61920.16800.83420.058*
C5A0.4973 (5)0.2775 (4)0.7325 (3)0.0563 (10)
H5AA0.43870.31850.79810.068*
C6A0.4744 (4)0.3068 (4)0.6165 (3)0.0546 (9)
H6AA0.39920.36720.60180.066*
C7A0.5616 (4)0.2476 (3)0.5202 (3)0.0441 (8)
H7AA0.54560.26900.44030.053*
C1B0.4294 (4)0.2041 (3)0.0757 (2)0.0343 (7)
C2B0.3615 (4)0.3199 (3)0.1284 (3)0.0434 (8)
H2BA0.42780.39430.18920.052*
C3B0.1994 (4)0.3253 (4)0.0920 (3)0.0492 (8)
H3BA0.15090.40290.12820.059*
C4B0.1052 (4)0.2177 (4)0.0020 (3)0.0495 (8)
H4BA−0.00760.2202−0.02580.059*
C5B0.1800 (4)0.1081 (4)−0.0453 (3)0.0416 (7)
H5BA0.11550.0336−0.10680.050*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Br0.0621 (3)0.0737 (3)0.0418 (2)0.01693 (18)−0.00365 (15)0.01454 (16)
N10.0608 (17)0.0325 (16)0.0236 (12)−0.0093 (12)−0.0039 (11)−0.0031 (10)
N20.0443 (15)0.0301 (15)0.0423 (13)0.0096 (12)−0.0114 (12)−0.0092 (11)
N30.0360 (14)0.0304 (14)0.0282 (12)0.0038 (10)−0.0026 (10)0.0016 (10)
C10.0394 (17)0.0335 (18)0.0242 (14)−0.0033 (13)0.0026 (12)−0.0020 (12)
C20.0414 (17)0.0313 (18)0.0255 (14)0.0038 (13)−0.0022 (12)−0.0071 (12)
C30.0469 (18)0.037 (2)0.0376 (16)0.0091 (15)0.0018 (14)0.0042 (14)
C40.056 (2)0.036 (2)0.0449 (18)0.0000 (15)0.0111 (16)0.0032 (14)
C50.052 (2)0.042 (2)0.0337 (16)−0.0149 (15)0.0044 (15)−0.0058 (14)
C60.052 (2)0.050 (2)0.0245 (14)−0.0113 (16)−0.0044 (13)−0.0005 (14)
C1A0.0429 (18)0.0388 (19)0.0280 (14)−0.0001 (13)0.0022 (12)0.0020 (12)
C2A0.0305 (16)0.0300 (17)0.0330 (15)−0.0077 (13)0.0005 (12)0.0001 (12)
C3A0.0389 (17)0.0340 (18)0.0325 (15)−0.0070 (13)0.0020 (13)0.0000 (12)
C4A0.055 (2)0.046 (2)0.0322 (16)−0.0092 (17)0.0068 (15)−0.0018 (14)
C5A0.060 (2)0.040 (2)0.060 (2)0.0016 (18)0.0256 (18)−0.0052 (17)
C6A0.051 (2)0.041 (2)0.072 (2)0.0117 (16)0.0156 (18)0.0075 (17)
C7A0.0418 (18)0.037 (2)0.0497 (18)0.0007 (15)0.0040 (14)0.0094 (14)
C1B0.0397 (17)0.0336 (18)0.0284 (14)0.0055 (13)0.0060 (13)0.0058 (12)
C2B0.052 (2)0.0335 (19)0.0420 (17)0.0080 (15)0.0057 (15)−0.0006 (13)
C3B0.054 (2)0.042 (2)0.058 (2)0.0196 (17)0.0179 (17)0.0119 (16)
C4B0.0390 (18)0.060 (2)0.054 (2)0.0136 (17)0.0071 (16)0.0197 (17)
C5B0.0356 (18)0.047 (2)0.0394 (16)0.0036 (15)−0.0004 (14)0.0095 (14)

Geometric parameters (Å, °)

Br—C3A1.900 (3)C1A—H1AA0.9900
N1—C11.389 (4)C1A—H1AB0.9900
N1—C1A1.446 (3)C2A—C7A1.377 (4)
N1—H1A0.8800C2A—C3A1.396 (4)
N2—C1B1.370 (3)C3A—C4A1.380 (4)
N2—C21.423 (3)C4A—C5A1.369 (5)
N2—H2A0.8800C4A—H4AA0.9500
N3—C5B1.336 (4)C5A—C6A1.372 (5)
N3—C1B1.347 (3)C5A—H5AA0.9500
C1—C21.397 (4)C6A—C7A1.398 (4)
C1—C61.401 (4)C6A—H6AA0.9500
C2—C31.384 (4)C7A—H7AA0.9500
C3—C41.383 (4)C1B—C2B1.393 (4)
C3—H3A0.9500C2B—C3B1.359 (4)
C4—C51.372 (4)C2B—H2BA0.9500
C4—H4A0.9500C3B—C4B1.384 (5)
C5—C61.377 (4)C3B—H3BA0.9500
C5—H5A0.9500C4B—C5B1.361 (4)
C6—H6A0.9500C4B—H4BA0.9500
C1A—C2A1.526 (4)C5B—H5BA0.9500
C1—N1—C1A123.2 (2)C7A—C2A—C1A122.8 (3)
C1—N1—H1A118.4C3A—C2A—C1A120.4 (3)
C1A—N1—H1A118.4C4A—C3A—C2A122.6 (3)
C1B—N2—C2124.4 (2)C4A—C3A—Br117.6 (2)
C1B—N2—H2A117.8C2A—C3A—Br119.8 (2)
C2—N2—H2A117.8C5A—C4A—C3A119.1 (3)
C5B—N3—C1B117.5 (2)C5A—C4A—H4AA120.4
N1—C1—C2119.3 (2)C3A—C4A—H4AA120.4
N1—C1—C6122.5 (3)C4A—C5A—C6A120.3 (3)
C2—C1—C6118.1 (3)C4A—C5A—H5AA119.9
C3—C2—C1120.1 (2)C6A—C5A—H5AA119.9
C3—C2—N2121.5 (3)C5A—C6A—C7A120.0 (3)
C1—C2—N2118.4 (3)C5A—C6A—H6AA120.0
C4—C3—C2121.1 (3)C7A—C6A—H6AA120.0
C4—C3—H3A119.5C2A—C7A—C6A121.3 (3)
C2—C3—H3A119.5C2A—C7A—H7AA119.4
C5—C4—C3118.9 (3)C6A—C7A—H7AA119.4
C5—C4—H4A120.5N3—C1B—N2115.0 (2)
C3—C4—H4A120.5N3—C1B—C2B121.4 (3)
C4—C5—C6121.1 (3)N2—C1B—C2B123.7 (3)
C4—C5—H5A119.4C3B—C2B—C1B119.3 (3)
C6—C5—H5A119.4C3B—C2B—H2BA120.4
C5—C6—C1120.6 (3)C1B—C2B—H2BA120.4
C5—C6—H6A119.7C2B—C3B—C4B119.8 (3)
C1—C6—H6A119.7C2B—C3B—H3BA120.1
N1—C1A—C2A115.7 (3)C4B—C3B—H3BA120.1
N1—C1A—H1AA108.4C5B—C4B—C3B117.5 (3)
C2A—C1A—H1AA108.4C5B—C4B—H4BA121.2
N1—C1A—H1AB108.4C3B—C4B—H4BA121.2
C2A—C1A—H1AB108.4N3—C5B—C4B124.5 (3)
H1AA—C1A—H1AB107.4N3—C5B—H5BA117.8
C7A—C2A—C3A116.8 (2)C4B—C5B—H5BA117.8
C1A—N1—C1—C2−162.8 (3)C7A—C2A—C3A—Br179.0 (2)
C1A—N1—C1—C618.9 (4)C1A—C2A—C3A—Br−1.2 (3)
N1—C1—C2—C3179.5 (2)C2A—C3A—C4A—C5A−1.0 (5)
C6—C1—C2—C3−2.0 (4)Br—C3A—C4A—C5A−179.2 (2)
N1—C1—C2—N2−0.4 (4)C3A—C4A—C5A—C6A0.8 (5)
C6—C1—C2—N2178.0 (2)C4A—C5A—C6A—C7A−0.6 (5)
C1B—N2—C2—C3−52.3 (4)C3A—C2A—C7A—C6A−0.6 (4)
C1B—N2—C2—C1127.6 (3)C1A—C2A—C7A—C6A179.6 (3)
C1—C2—C3—C4−0.2 (4)C5A—C6A—C7A—C2A0.4 (5)
N2—C2—C3—C4179.7 (3)C5B—N3—C1B—N2178.6 (2)
C2—C3—C4—C52.1 (4)C5B—N3—C1B—C2B0.2 (4)
C3—C4—C5—C6−1.8 (5)C2—N2—C1B—N3167.2 (2)
C4—C5—C6—C1−0.4 (5)C2—N2—C1B—C2B−14.5 (4)
N1—C1—C6—C5−179.3 (3)N3—C1B—C2B—C3B0.5 (4)
C2—C1—C6—C52.3 (4)N2—C1B—C2B—C3B−177.8 (3)
C1—N1—C1A—C2A68.9 (3)C1B—C2B—C3B—C4B−1.1 (5)
N1—C1A—C2A—C7A−0.8 (4)C2B—C3B—C4B—C5B1.0 (5)
N1—C1A—C2A—C3A179.4 (2)C1B—N3—C5B—C4B−0.3 (4)
C7A—C2A—C3A—C4A0.9 (4)C3B—C4B—C5B—N3−0.3 (5)
C1A—C2A—C3A—C4A−179.3 (3)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N2—H2A···N3i0.882.082.952 (3)175

Symmetry codes: (i) −x+1, −y, −z.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BT5071).

References

  • Albéniz, A. C., Espinet, P., Manrique, R. & Pérez-Mateo, A. (2002). Angew. Chem. Int. Ed.41, 2363–2366. [PubMed]
  • Denk, M. K., Rodezno, J. M., Gupta, S. & Lough, L. J. (2001). J. Organomet. Chem.617, 242–253.
  • Dutton, J. L., Tabeshi, R., Jennings, M. C., Logh, A. J. & Ragogna, P. J. (2007). Inorg. Chem.46, 8594–8602. [PubMed]
  • Hahn, F. E., Jahnke, M. C. & Pape, T. (2007). Organometallics, 26, 150–154.
  • Huynh, H. V., Han, Y., Ho, J. H. H. & Tan, G. K. (2006). Organometallics, 25, 3267–3274.
  • Kuhn, N., Henkel, G. & Kratz, T. (1993). Chem. Ber.126, 2047–2049.
  • Oxford Diffraction (2009). CrysAlis Pro Oxford Diffraction Ltd, Yarnton, Oxfordshire, England.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]

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