2-Isobutyl-6-(4-meth­oxy­phen­yl)imidazo[2,1-b][1,3,4]thia­diazole

Fun, H.-K.; Yeap, C.S.; Prasad, D.J.; Castelino, P.A.; Anitha, V.V.

doi:10.1107/S1600536810053225

organic compounds

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ISSN: 2056-9890

Volume 67| Part 2| February 2011| Page o255

doi:10.1107/S1600536810053225

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2-Isobutyl-6-(4-methoxyphenyl)imidazo[2,1-b][1,3,4]thiadiazole

Hoong-Kun Fun,^a ^*‡ Chin Sing Yeap,^a § D. Jagadeesh Prasad,^b Prakash Anil Castelino ^c and V. V. Anitha ^b

^aX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia, ^bDepartment of Chemistry, Mangalore University, Mangalore, Karnataka, India, and ^cSt. Philomena's College, Puttur, Dakshina Kannada, Karnataka, India
^*Correspondence e-mail: hkfun@usm.my

(Received 17 December 2010; accepted 18 December 2010; online 8 January 2011)

In the title compound, C₁₅H₁₇N₃OS, the dihedral angle between the statistically planar imidazo[2,1-b][1,3,4]thiadiazole fused-ring system (r.m.s. deviation = 0.002 Å) and the methyoxbenzene ring is 4.52 (6)°. In the crystal, molecules are arranged into columns and stacked down the a axis. The crystal structure is stabilized by weak C—H⋯π and π–π interactions [centroid–centroid separations = 3.6053 (8) and 3.7088 (7) Å].

Related literature

For a related structure and background references to imidazo[2,1-b]-1,3,4-thiadiazole derivatives, see: Fun et al. (2011 ).

Experimental

Crystal data

C₁₅H₁₇N₃OS
M_r = 287.38
Triclinic, $[P \overline 1]$
a = 5.7139 (1) Å
b = 10.1795 (1) Å
c = 12.9689 (2) Å
α = 85.174 (1)°
β = 85.164 (1)°
γ = 80.690 (1)°
V = 739.84 (2) Å³
Z = 2
Mo Kα radiation
μ = 0.22 mm⁻¹
T = 296 K
0.43 × 0.31 × 0.17 mm

Data collection

Bruker SMART APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ) T_min = 0.911, T_max = 0.964
23503 measured reflections
6213 independent reflections
3805 reflections with I > 2σ(I)
R_int = 0.028

Refinement

R[F² > 2σ(F²)] = 0.053
wR(F²) = 0.163
S = 1.03
6213 reflections
181 parameters
H-atom parameters constrained
Δρ_max = 0.30 e Å⁻³
Δρ_min = −0.28 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

Cg3 is the centroid of the C1–C6 benzene ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C11—H11A⋯Cg3ⁱ	0.97	2.60	3.5063 (16)	155
Symmetry code: (i) -x+2, -y+2, -z+1.

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810053225/hb5778sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536810053225/hb5778Isup2.hkl

checkCIF report

Comment top

As part of our ongoing synthetic and structural studies of imidazo[2,1-b]-1,3,4-thiadiazole derivatives (Fun et al., 2011), we now report the structure of the title compound, (I).

The mean plane through the imidazo[2,1-b]-1,3,4-thiadiazole ring and the methoxyphenyl moiety is essentially planar with the maximum deviation of 0.045 Å for atom C2 (Fig. 1). The isobutyl is twisted away from this mean plane with torsion angles of C9–C11–C12–C13 = 64.3 (2)° and C9–C11–C12–C14 = -172.81 (17)°. In the crystal structure, the molecules are arranged into columns and stacked down a axis (Fig. 2). The molecules are stabilized by the weak Cg1···Cg2ⁱ = 3.7088 (7) Å, Cg2···Cg2ⁱ = 3.6053 (8) Å and C11–H11A···Cg3ⁱ interactions [Cg1, Cg2 and Cg3 are centroids of S1/C9/N1/N2/C10, N2/C8/C7/N3/C10 and C–C6 ring respectively; (i) 2 - x, 2 - y, 1 - z].

Related literature top

For a related structure and background references to imidazo[2,1-b]-1,3,4-thiadiazole derivatives, see: Fun et al. (2011).

Experimental top

5-Isobutyl-1,3,4-thiadiazol-2-amine (1 molar equivalent) and 4-methoxyphenacylbromide (1 molar equivalent) are refluxed with ethanol for 4 h. The solvent was then distilled and the reaction mass was poured onto the crushed ice. The resulting solid that separated out was filtered and dried. The compound was re-crystallized using ethanol and DMF mixture to yield colourless blocks of (I). M.P.: 118–122°C.

Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top

	Fig. 1. The molecular structure of (I) with 30% probability ellipsoids for non-H atoms.
	Fig. 2. The crystal packing of (I), viewed down the a axis, showing molecules stacked down a axis.

2-Isobutyl-6-(4-methoxyphenyl)imidazo[2,1-b][1,3,4]thiadiazole top

Crystal data top

C₁₅H₁₇N₃OS	Z = 2
M_r = 287.38	F(000) = 304
Triclinic, P1	D_x = 1.290 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 5.7139 (1) Å	Cell parameters from 6150 reflections
b = 10.1795 (1) Å	θ = 2.5–30.1°
c = 12.9689 (2) Å	µ = 0.22 mm⁻¹
α = 85.174 (1)°	T = 296 K
β = 85.164 (1)°	Block, colourless
γ = 80.690 (1)°	0.43 × 0.31 × 0.17 mm
V = 739.84 (2) Å³

Data collection top

Bruker SMART APEXII CCD diffractometer	6213 independent reflections
Radiation source: fine-focus sealed tube	3805 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.028
ϕ and ω scans	θ_max = 34.5°, θ_min = 1.6°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −9→9
T_min = 0.911, T_max = 0.964	k = −16→16
23503 measured reflections	l = −20→20

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.053	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.163	H-atom parameters constrained
S = 1.03	w = 1/[σ²(F_o²) + (0.0765P)² + 0.0748P] where P = (F_o² + 2F_c²)/3
6213 reflections	(Δ/σ)_max < 0.001
181 parameters	Δρ_max = 0.30 e Å⁻³
0 restraints	Δρ_min = −0.28 e Å⁻³

Crystal data top

C₁₅H₁₇N₃OS	γ = 80.690 (1)°
M_r = 287.38	V = 739.84 (2) Å³
Triclinic, P1	Z = 2
a = 5.7139 (1) Å	Mo Kα radiation
b = 10.1795 (1) Å	µ = 0.22 mm⁻¹
c = 12.9689 (2) Å	T = 296 K
α = 85.174 (1)°	0.43 × 0.31 × 0.17 mm
β = 85.164 (1)°

Data collection top

Bruker SMART APEXII CCD diffractometer	6213 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2009)	3805 reflections with I > 2σ(I)
T_min = 0.911, T_max = 0.964	R_int = 0.028
23503 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.053	0 restraints
wR(F²) = 0.163	H-atom parameters constrained
S = 1.03	Δρ_max = 0.30 e Å⁻³
6213 reflections	Δρ_min = −0.28 e Å⁻³
181 parameters

Special details top

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) top

	x	y	z	U_iso*/U_eq
S1	1.14439 (6)	1.02701 (4)	0.26563 (3)	0.05911 (14)
O1	1.1085 (2)	0.33486 (12)	0.78317 (9)	0.0741 (3)
N1	0.7031 (2)	1.05243 (12)	0.33719 (9)	0.0523 (3)
N2	0.82991 (18)	0.94641 (11)	0.39100 (8)	0.0448 (2)
N3	1.16801 (18)	0.81311 (11)	0.42311 (8)	0.0470 (2)
C1	1.2380 (2)	0.58244 (13)	0.57132 (10)	0.0459 (3)
H1A	1.3637	0.6030	0.5258	0.055*
C2	1.2769 (3)	0.47212 (13)	0.64264 (10)	0.0498 (3)
H2A	1.4261	0.4199	0.6442	0.060*
C3	1.0917 (3)	0.44125 (14)	0.71078 (10)	0.0515 (3)
C4	0.8704 (3)	0.52078 (17)	0.70788 (12)	0.0620 (4)
H4A	0.7456	0.5008	0.7542	0.074*
C5	0.8345 (2)	0.62946 (16)	0.63658 (12)	0.0541 (3)
H5A	0.6852	0.6817	0.6354	0.065*
C6	1.0186 (2)	0.66223 (12)	0.56621 (9)	0.0405 (2)
C7	0.9808 (2)	0.77580 (12)	0.48936 (9)	0.0397 (2)
C8	0.7710 (2)	0.85747 (13)	0.47028 (10)	0.0497 (3)
H8A	0.6217	0.8533	0.5038	0.060*
C9	0.8461 (2)	1.10357 (13)	0.26920 (10)	0.0473 (3)
C10	1.0665 (2)	0.91576 (13)	0.36590 (9)	0.0441 (3)
C11	0.7678 (3)	1.22647 (14)	0.20133 (11)	0.0571 (4)
H11A	0.8370	1.2992	0.2240	0.069*
H11B	0.5965	1.2493	0.2123	0.069*
C12	0.8305 (3)	1.21810 (16)	0.08633 (11)	0.0642 (4)
H12A	1.0026	1.1905	0.0754	0.077*
C13	0.7083 (6)	1.1178 (2)	0.04179 (17)	0.1097 (9)
H13A	0.7482	1.0322	0.0783	0.165*
H13B	0.7594	1.1119	−0.0303	0.165*
H13C	0.5393	1.1455	0.0489	0.165*
C14	0.7663 (6)	1.3557 (2)	0.03141 (17)	0.1117 (9)
H14A	0.8461	1.4183	0.0607	0.167*
H14B	0.5975	1.3836	0.0400	0.167*
H14C	0.8148	1.3522	−0.0411	0.167*
C15	1.3354 (4)	0.25718 (19)	0.79377 (16)	0.0840 (6)
H15A	1.3233	0.1863	0.8467	0.126*
H15B	1.4436	0.3125	0.8127	0.126*
H15C	1.3931	0.2200	0.7291	0.126*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
S1	0.04595 (19)	0.0694 (3)	0.0549 (2)	−0.00092 (16)	0.00022 (14)	0.01745 (17)
O1	0.0866 (8)	0.0673 (7)	0.0650 (7)	−0.0162 (6)	−0.0051 (6)	0.0229 (5)
N1	0.0439 (6)	0.0567 (7)	0.0504 (6)	0.0074 (5)	−0.0069 (5)	0.0047 (5)
N2	0.0364 (5)	0.0504 (6)	0.0438 (5)	0.0022 (4)	−0.0044 (4)	0.0022 (4)
N3	0.0361 (5)	0.0551 (6)	0.0462 (6)	−0.0009 (4)	−0.0031 (4)	0.0060 (4)
C1	0.0453 (6)	0.0489 (7)	0.0394 (6)	0.0004 (5)	0.0018 (5)	0.0001 (5)
C2	0.0532 (7)	0.0483 (7)	0.0440 (6)	0.0019 (5)	−0.0021 (5)	−0.0004 (5)
C3	0.0644 (8)	0.0468 (7)	0.0441 (6)	−0.0126 (6)	−0.0077 (6)	0.0034 (5)
C4	0.0531 (8)	0.0731 (10)	0.0584 (8)	−0.0177 (7)	0.0027 (6)	0.0119 (7)
C5	0.0394 (6)	0.0654 (8)	0.0546 (7)	−0.0063 (6)	0.0001 (5)	0.0060 (6)
C6	0.0395 (6)	0.0448 (6)	0.0374 (5)	−0.0054 (5)	−0.0040 (4)	−0.0050 (4)
C7	0.0372 (5)	0.0445 (6)	0.0365 (5)	−0.0023 (4)	−0.0035 (4)	−0.0050 (4)
C8	0.0375 (6)	0.0565 (8)	0.0505 (7)	−0.0008 (5)	0.0019 (5)	0.0051 (6)
C9	0.0514 (7)	0.0489 (7)	0.0394 (6)	0.0027 (5)	−0.0096 (5)	−0.0042 (5)
C10	0.0364 (6)	0.0528 (7)	0.0409 (6)	−0.0022 (5)	−0.0038 (4)	0.0010 (5)
C11	0.0711 (9)	0.0495 (7)	0.0465 (7)	0.0050 (6)	−0.0117 (6)	0.0006 (5)
C12	0.0702 (10)	0.0673 (9)	0.0486 (8)	0.0017 (8)	−0.0023 (7)	0.0078 (7)
C13	0.175 (3)	0.0923 (15)	0.0672 (12)	−0.0145 (17)	−0.0461 (15)	−0.0119 (11)
C14	0.164 (3)	0.0872 (14)	0.0717 (13)	−0.0059 (16)	−0.0039 (14)	0.0319 (11)
C15	0.1056 (16)	0.0615 (10)	0.0816 (12)	−0.0074 (10)	−0.0270 (11)	0.0232 (9)

Geometric parameters (Å, º) top

S1—C10	1.7290 (13)	C6—C7	1.4622 (16)
S1—C9	1.7545 (14)	C7—C8	1.3722 (17)
O1—C3	1.3690 (16)	C8—H8A	0.9300
O1—C15	1.416 (2)	C9—C11	1.4966 (18)
N1—C9	1.2864 (19)	C11—C12	1.510 (2)
N1—N2	1.3721 (14)	C11—H11A	0.9700
N2—C10	1.3554 (16)	C11—H11B	0.9700
N2—C8	1.3689 (16)	C12—C13	1.503 (3)
N3—C10	1.3133 (15)	C12—C14	1.521 (2)
N3—C7	1.3957 (16)	C12—H12A	0.9800
C1—C6	1.3825 (17)	C13—H13A	0.9600
C1—C2	1.3947 (17)	C13—H13B	0.9600
C1—H1A	0.9300	C13—H13C	0.9600
C2—C3	1.379 (2)	C14—H14A	0.9600
C2—H2A	0.9300	C14—H14B	0.9600
C3—C4	1.388 (2)	C14—H14C	0.9600
C4—C5	1.381 (2)	C15—H15A	0.9600
C4—H4A	0.9300	C15—H15B	0.9600
C5—C6	1.3967 (18)	C15—H15C	0.9600
C5—H5A	0.9300

C10—S1—C9	88.40 (6)	N3—C10—N2	112.76 (11)
C3—O1—C15	117.66 (14)	N3—C10—S1	138.85 (10)
C9—N1—N2	108.55 (11)	N2—C10—S1	108.39 (9)
C10—N2—C8	107.69 (10)	C9—C11—C12	116.36 (12)
C10—N2—N1	118.51 (11)	C9—C11—H11A	108.2
C8—N2—N1	133.79 (11)	C12—C11—H11A	108.2
C10—N3—C7	103.73 (10)	C9—C11—H11B	108.2
C6—C1—C2	122.09 (12)	C12—C11—H11B	108.2
C6—C1—H1A	119.0	H11A—C11—H11B	107.4
C2—C1—H1A	119.0	C13—C12—C11	112.03 (16)
C3—C2—C1	119.33 (13)	C13—C12—C14	110.67 (17)
C3—C2—H2A	120.3	C11—C12—C14	109.10 (15)
C1—C2—H2A	120.3	C13—C12—H12A	108.3
O1—C3—C2	124.39 (14)	C11—C12—H12A	108.3
O1—C3—C4	115.99 (14)	C14—C12—H12A	108.3
C2—C3—C4	119.62 (13)	C12—C13—H13A	109.5
C5—C4—C3	120.36 (14)	C12—C13—H13B	109.5
C5—C4—H4A	119.8	H13A—C13—H13B	109.5
C3—C4—H4A	119.8	C12—C13—H13C	109.5
C4—C5—C6	121.14 (14)	H13A—C13—H13C	109.5
C4—C5—H5A	119.4	H13B—C13—H13C	109.5
C6—C5—H5A	119.4	C12—C14—H14A	109.5
C1—C6—C5	117.46 (12)	C12—C14—H14B	109.5
C1—C6—C7	121.12 (11)	H14A—C14—H14B	109.5
C5—C6—C7	121.42 (11)	C12—C14—H14C	109.5
C8—C7—N3	111.03 (11)	H14A—C14—H14C	109.5
C8—C7—C6	127.62 (11)	H14B—C14—H14C	109.5
N3—C7—C6	121.35 (10)	O1—C15—H15A	109.5
N2—C8—C7	104.79 (11)	O1—C15—H15B	109.5
N2—C8—H8A	127.6	H15A—C15—H15B	109.5
C7—C8—H8A	127.6	O1—C15—H15C	109.5
N1—C9—C11	122.38 (13)	H15A—C15—H15C	109.5
N1—C9—S1	116.15 (10)	H15B—C15—H15C	109.5
C11—C9—S1	121.36 (11)

C9—N1—N2—C10	0.23 (17)	C10—N2—C8—C7	0.06 (15)
C9—N1—N2—C8	179.94 (14)	N1—N2—C8—C7	−179.67 (13)
C6—C1—C2—C3	−0.3 (2)	N3—C7—C8—N2	0.03 (15)
C15—O1—C3—C2	4.8 (2)	C6—C7—C8—N2	−179.34 (11)
C15—O1—C3—C4	−175.43 (15)	N2—N1—C9—C11	−176.23 (11)
C1—C2—C3—O1	179.30 (13)	N2—N1—C9—S1	−0.04 (15)
C1—C2—C3—C4	−0.4 (2)	C10—S1—C9—N1	−0.10 (12)
O1—C3—C4—C5	−179.11 (14)	C10—S1—C9—C11	176.13 (11)
C2—C3—C4—C5	0.7 (2)	C7—N3—C10—N2	0.14 (15)
C3—C4—C5—C6	−0.2 (2)	C7—N3—C10—S1	−179.92 (13)
C2—C1—C6—C5	0.7 (2)	C8—N2—C10—N3	−0.13 (16)
C2—C1—C6—C7	−178.73 (12)	N1—N2—C10—N3	179.65 (11)
C4—C5—C6—C1	−0.5 (2)	C8—N2—C10—S1	179.92 (9)
C4—C5—C6—C7	178.95 (13)	N1—N2—C10—S1	−0.31 (15)
C10—N3—C7—C8	−0.10 (14)	C9—S1—C10—N3	−179.73 (16)
C10—N3—C7—C6	179.31 (11)	C9—S1—C10—N2	0.21 (10)
C1—C6—C7—C8	175.00 (13)	N1—C9—C11—C12	−129.32 (16)
C5—C6—C7—C8	−4.5 (2)	S1—C9—C11—C12	54.69 (18)
C1—C6—C7—N3	−4.31 (18)	C9—C11—C12—C13	64.3 (2)
C5—C6—C7—N3	176.24 (12)	C9—C11—C12—C14	−172.81 (17)

Hydrogen-bond geometry (Å, º) top

Cg3 is the centroid of the C1–C6 benzene ring.

D—H···A	D—H	H···A	D···A	D—H···A
C11—H11A···Cg3ⁱ	0.97	2.60	3.5063 (16)	155

Symmetry code: (i) −x+2, −y+2, −z+1.

Experimental details

Crystal data
Chemical formula	C₁₅H₁₇N₃OS
M_r	287.38
Crystal system, space group	Triclinic, P1
Temperature (K)	296
a, b, c (Å)	5.7139 (1), 10.1795 (1), 12.9689 (2)
α, β, γ (°)	85.174 (1), 85.164 (1), 80.690 (1)
V (Å³)	739.84 (2)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.22
Crystal size (mm)	0.43 × 0.31 × 0.17

Data collection
Diffractometer	Bruker SMART APEXII CCD diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2009)
T_min, T_max	0.911, 0.964
No. of measured, independent and observed [I > 2σ(I)] reflections	23503, 6213, 3805
R_int	0.028
(sin θ/λ)_max (Å⁻¹)	0.797

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.053, 0.163, 1.03
No. of reflections	6213
No. of parameters	181
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.30, −0.28

Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top

Cg3 is the centroid of the C1–C6 benzene ring.

D—H···A	D—H	H···A	D···A	D—H···A
C11—H11A···Cg3ⁱ	0.97	2.60	3.5063 (16)	155

Symmetry code: (i) −x+2, −y+2, −z+1.

Footnotes

‡Thomson Reuters ResearcherID: A-3561-2009.

§Thomson Reuters ResearcherID: A-5523-2009.

Acknowledgements

HKF and CSY thank Universiti Sains Malaysia (USM) for the Research University Grant No. 1001/PFIZIK/811160.

References

Bruker (2009). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Fun, H.-K., Hemamalini, M., Prasad, D. J., Castelino, P. A. & Anitha, V. V. (2011). Acta Cryst. E67, o254. Web of Science CSD CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar

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Volume 67| Part 2| February 2011| Page o255

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