organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2056-9890
Volume 69| Part 5| May 2013| Pages o654-o655

1,3-Di­iodo­azulene-2-carbo­nitrile

aInstitut für Organische Chemie, TU Bergakademie Freiberg, Leipziger Strasse 29, D-09596 Freiberg/Sachsen, Germany
*Correspondence e-mail: edwin.weber@chemie.tu-freiberg.de

(Received 25 February 2013; accepted 26 March 2013; online 5 April 2013)

In the title compound, C11H5I2N, the two iodine-atom substitutents with their large atomic sizes lead to short intra­molecular I⋯H distances (3.01 Å). In the crystal, the tris­ubstituted azulene system forms π-stacks [centroid–centroid distance = 3.6343 (11) Å] along the a-axis direction, showing the characteristic azulene inter­action mode between the electron-rich five-membered ring and the electron-deficient seven-membered ring. I⋯I [3.9129 (2) Å] non-covalent contacts are observed along with weak C—H⋯N and C—H⋯π. bonds.

Related literature

For the naphthalene isomer azulene, see: Plattner & Pfau (1937[Plattner, P. A. & Pfau, A. S. (1937). Helv. Chim. Acta, 19, 858-879.]). For the use of azulene derivatives for medical purposes, see: Shi et al. (2011[Shi, W., Zuo, Z., Deng, C., Shi, C. & Xu, K. (2011). CN Patent No. 102114010.]). The synthesis of the title compound was performed starting from the azulene derivative 2-cyano­azulene (Nozoe et al., 1962[Nozoe, T., Seto, S. & Matsumura, S. (1962). Bull. Chem. Soc. Jpn, 35, 1990-1998.]). For the synthesis of related compounds, see Schmitt et al. (1998[Schmitt, S., Baumgarten, M., Simon, J. & Hafner, K. (1998). Angew. Chem. Int. Ed. 29, 1077-1081.]); Suzuka & Yasunami (2008[Suzuka, I. & Yasunami, M. (2008). Jpn Patent No. 2008285435.]). For related structures, see: Förster et al. (2012[Förster, S., Hahn, T., Loose, C., Röder, C., Liebing, S., Seichter, W., Ei\, F., Kortus, J. & Weber, E. (2012). J. Phys. Org. Chem. 25, 856-863.]); Hussain et al. (2005[Hussain, Z., Oeser, T. & Hopf, H. (2005). Acta Cryst. E61, o478-o479.]); Rahman et al. (2004[Rahman, M., Murafuji, T., Kurotobi, K. & Sugihara, Y. (2004). Organometallics, 23, 6176-6183.]). For halogen inter­actions in mol­ecular crystal structures, see: Awwadi et al. (2006[Awwadi, F. F., Willett, R. D., Peterson, K. A. & Twamley, B. (2006). Chem. Eur. J. 12, 8952-896.]); Metrangolo et al. (2008[Metrangolo, P., Resnati, G., Pilati, T. & Biella, S. (2008). Struct. Bond. 126, 105-136.]). For weak C—H⋯N hydrogen bonding, see: Desiraju & Steiner (1999[Desiraju, G. R. & Steiner, T. (1999). The Weak Hydrogen Bond, pp. 29-123. Oxford University Press.]). For C—H⋯π inter­actions, see: Nishio et al. (2009[Nishio, M., Umezawa, Y., Honda, K., Tsuboyama, S. & Suezawa, H. (2009). CrystEngComm, 11, 1757-1788.]).

[Scheme 1]

Experimental

Crystal data
  • C11H5I2N

  • Mr = 404.96

  • Monoclinic, P 21 /n

  • a = 4.2677 (1) Å

  • b = 14.9344 (4) Å

  • c = 16.7882 (4) Å

  • β = 96.952 (1)°

  • V = 1062.14 (5) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 5.88 mm−1

  • T = 100 K

  • 0.52 × 0.07 × 0.03 mm

Data collection
  • Bruker APEXII CCD area-detector diffractometer

  • Absorption correction: multi-scan (SADABS; Sheldrick, 2007)[Sheldrick, G. M. (2007). SADABS. University of Göttingen, Germany.] Tmin = 0.150, Tmax = 0.843

  • 17691 measured reflections

  • 4616 independent reflections

  • 3863 reflections with I > 2σ(I)

  • Rint = 0.023

Refinement
  • R[F2 > 2σ(F2)] = 0.024

  • wR(F2) = 0.058

  • S = 1.05

  • 4616 reflections

  • 127 parameters

  • H-atom parameters constrained

  • Δρmax = 1.48 e Å−3

  • Δρmin = −1.32 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

Cg(C11—N1) is the mid-point of the C11—N1 bond.

D—H⋯A D—H H⋯A DA D—H⋯A
C8—H8⋯N1i 0.95 2.62 3.400 (3) 139
C6—H6⋯Cg(C11—N1)i 0.95 2.76 3.63 (3) 152
Symmetry code: (i) [x-{\script{3\over 2}}, -y+{\script{1\over 2}}, z-{\script{1\over 2}}].

Data collection: APEX2 (Bruker, 2007[Bruker (2007). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2007[Bruker (2007). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012[Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849-854.]); software used to prepare material for publication: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]).

Supporting information


Comment top

The naphthalene isomer azulene is a well known blue nonbenzenoid aromatic hydrocarbon (Plattner 1937). Besides the use of azulene derivatives for medical purposes (Shi 2011), special electronic properties and redox behaviour makes them interesting compounds for electronic applications (Förster et al. 2012). In this regard, the present trisubstituted azulene derivative is a promising intermediate. In the crystal structure of this compound, the asymmetric unit contains one molecule featuring an almost planar azulene ring system with a maximum deviations of 0.023 (2) and 0.023 (2) Å (Fig.1). Short intramolecular distances (3.01 Å) involving the iodine atoms and their neighboring H atoms (I1···H9, I2···H5) are a further characteristic of the molecular structur. Along the crystallographic a-axis, the crystal structure is stabilized by formation of molecular stacks with a distance of 3.46 Å between the planes of the molecules. The parallel orientated azulene ring systems are arranged in an offset face-to-face fashion showing π···π overlap between the five- and seven-membered ring components in conformity with their dipole character. In direction of the crystallographic b and c axes, these stacks are connected via C—H···N contacts [C8—H8···N1 (3/2+x,1/2-y,1/2+z) 2.62 Å, 139.1°] (Desiraju & Steiner, 1999), I···I interactions [I1···I2 (3/2-x,-1/2+y,1/2-z) 3.91 Å, 91°] (Metrangolo et al., 2008) and C—H···π contacts [C6—H6···center(C11, N1) (1/2-x,-1/2+y,1/2-z) 2.76 Å, 152.6°] (Nishio et al., 2009) (Fig 2).

Related literature top

For the naphthalene isomer azulene, see: Plattner & Pfau (1937). For the use of azulene derivatives for medical purposes, see: Shi et al. (2011). The synthesis of the title compound was performed starting from the azulene derivative 2-cyanoazulene (Nozoe et al., 1962). For the synthesis of related compounds, see Schmitt et al. (1998); Suzuka & Yasunami (2008). For related structures, see: Förster et al. (2012); Hussain et al. (2005); Rahman et al. (2004). For halogen interactions in molecular crystal structures, see: Awwadi et al. (2006); Metrangolo et al. (2008). For weak C—H···N hydrogen bonding, see: Desiraju & Steiner (1999). For C—H···π interactions, see: Nishio et al. (2009).

Experimental top

The synthesis of the title compound was done starting from the literature known azulene derivative 2-cyanoazulene (Nozoe et al., 1962). This latter compound (0.1 g, 0.65 mmol) and N-iodosuccinimide (0.44 g, 1.96 mmol) were dissolved in 20 ml dichloromethane. The solution was stirred for 8 h under reflux. After removal of the solvent, the residue was purified by column chromatography on SiO2 [60 F254 Merck eluent: hexane/ethyl acetate (4:1)] to yield 0.24 g (91%) product as a green solid. Analytical data: mp = 211°C; 1H-NMR: (CDCl3) δ/p.p.m. = 7.46 (t, 2 H, ArH, 3JHH = 9.78 Hz), 7.83 (t, 1 H, ArH, 3JHH = 9.85 Hz), 8.30 (d, 2 H, ArH, 3JHH = 9.95 Hz); 13C-NMR: (CDCl3) δ/p.p.m. = 78.41(ArC), 117.30(CN), 126.86(ArC), 129.23(ArC), 141.00(ArC), 142.82(ArC), 143.06(ArC); GC/MS calc.: 405; found: 405 [M]+.. Crystallization by slow evaporation from n-hexane yielded suitable crystals.

Refinement top

Aromatic H atoms were positioned geometrically and allowed to ride on their respective parent atoms, with C—H = 0.95 Å and Uiso = 1.2 Ueq(C).

Computing details top

Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. Asymmetric unit of the title compound, showing the atom numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.
[Figure 2] Fig. 2. A view along the a axis of the crystal packing of the title compound. Intermolecular interactions are represented as dashed lines.
1,3-Diiodoazulene-2-carbonitrile top
Crystal data top
C11H5I2NF(000) = 736
Mr = 404.96Dx = 2.532 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 7883 reflections
a = 4.2677 (1) Åθ = 2.7–36.5°
b = 14.9344 (4) ŵ = 5.88 mm1
c = 16.7882 (4) ÅT = 100 K
β = 96.952 (1)°Needle, green
V = 1062.14 (5) Å30.52 × 0.07 × 0.03 mm
Z = 4
Data collection top
Bruker APEXII CCD area-detector
diffractometer
4616 independent reflections
Radiation source: fine-focus sealed tube3863 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.023
phi and ω scansθmax = 35.1°, θmin = 1.8°
Absorption correction: multi-scan
(SADABS; Sheldrick, 2007)
h = 64
Tmin = 0.150, Tmax = 0.843k = 2422
17691 measured reflectionsl = 2427
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.024Hydrogen site location: difference Fourier map
wR(F2) = 0.058H-atom parameters constrained
S = 1.05 w = 1/[σ2(Fo2) + (0.0289P)2 + 0.3529P]
where P = (Fo2 + 2Fc2)/3
4616 reflections(Δ/σ)max = 0.001
127 parametersΔρmax = 1.48 e Å3
0 restraintsΔρmin = 1.32 e Å3
Crystal data top
C11H5I2NV = 1062.14 (5) Å3
Mr = 404.96Z = 4
Monoclinic, P21/nMo Kα radiation
a = 4.2677 (1) ŵ = 5.88 mm1
b = 14.9344 (4) ÅT = 100 K
c = 16.7882 (4) Å0.52 × 0.07 × 0.03 mm
β = 96.952 (1)°
Data collection top
Bruker APEXII CCD area-detector
diffractometer
4616 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2007)
3863 reflections with I > 2σ(I)
Tmin = 0.150, Tmax = 0.843Rint = 0.023
17691 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0240 restraints
wR(F2) = 0.058H-atom parameters constrained
S = 1.05Δρmax = 1.48 e Å3
4616 reflectionsΔρmin = 1.32 e Å3
127 parameters
Special details top

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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
xyzUiso*/Ueq
I10.78365 (3)0.118650 (8)0.153674 (8)0.01453 (4)
I20.54859 (3)0.379652 (8)0.426773 (8)0.01708 (4)
N11.0480 (4)0.14850 (13)0.39516 (11)0.0216 (4)
C10.6331 (4)0.23056 (12)0.21157 (11)0.0131 (3)
C20.7006 (4)0.24765 (12)0.29426 (11)0.0129 (3)
C30.5399 (4)0.32630 (12)0.31275 (11)0.0131 (3)
C40.3685 (4)0.35906 (12)0.24230 (11)0.0126 (3)
C100.4300 (4)0.29734 (12)0.17661 (11)0.0126 (3)
C90.3126 (5)0.30350 (13)0.09587 (12)0.0157 (3)
H90.38520.25910.06200.019*
C80.1030 (5)0.36596 (14)0.05796 (12)0.0182 (4)
H80.05090.35810.00180.022*
C70.0398 (5)0.43785 (14)0.09082 (13)0.0186 (4)
H70.18030.47140.05400.022*
C60.0090 (5)0.46858 (13)0.16964 (13)0.0178 (4)
H60.12790.52060.17880.021*
C50.1722 (4)0.43354 (12)0.23683 (12)0.0148 (3)
H50.16010.46480.28560.018*
C110.8938 (5)0.19344 (13)0.35015 (12)0.0151 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
I10.01660 (6)0.01155 (6)0.01611 (6)0.00045 (4)0.00466 (4)0.00113 (4)
I20.02230 (7)0.01668 (6)0.01229 (6)0.00117 (4)0.00219 (4)0.00198 (4)
N10.0239 (9)0.0197 (8)0.0198 (9)0.0022 (7)0.0036 (7)0.0007 (7)
C10.0144 (7)0.0101 (7)0.0152 (8)0.0011 (6)0.0029 (6)0.0011 (6)
C20.0131 (7)0.0110 (7)0.0145 (8)0.0006 (6)0.0020 (6)0.0001 (6)
C30.0150 (8)0.0117 (7)0.0127 (8)0.0010 (6)0.0022 (6)0.0011 (6)
C40.0131 (7)0.0113 (7)0.0136 (8)0.0022 (6)0.0027 (6)0.0001 (6)
C100.0137 (7)0.0109 (7)0.0134 (8)0.0013 (6)0.0026 (6)0.0001 (6)
C90.0177 (8)0.0147 (8)0.0146 (8)0.0023 (6)0.0017 (6)0.0003 (6)
C80.0200 (9)0.0204 (9)0.0133 (8)0.0017 (7)0.0008 (7)0.0031 (7)
C70.0161 (8)0.0212 (9)0.0181 (9)0.0006 (7)0.0004 (7)0.0067 (7)
C60.0168 (8)0.0132 (8)0.0234 (10)0.0024 (6)0.0026 (7)0.0033 (7)
C50.0156 (8)0.0116 (7)0.0178 (9)0.0002 (6)0.0044 (7)0.0001 (6)
C110.0161 (8)0.0129 (8)0.0162 (8)0.0009 (6)0.0017 (6)0.0019 (6)
Geometric parameters (Å, º) top
I1—C12.0741 (18)C10—C91.390 (3)
I2—C32.0697 (19)C9—C81.392 (3)
N1—C111.155 (3)C9—H90.9500
C1—C101.403 (3)C8—C71.382 (3)
C1—C21.407 (3)C8—H80.9500
C2—C31.413 (3)C7—C61.392 (3)
C2—C111.424 (3)C7—H70.9500
C3—C41.401 (3)C6—C51.390 (3)
C4—C51.389 (3)C6—H60.9500
C4—C101.485 (3)C5—H50.9500
C10—C1—C2109.05 (16)C10—C9—H9115.6
C10—C1—I1125.99 (14)C8—C9—H9115.6
C2—C1—I1124.80 (13)C7—C8—C9128.91 (19)
C1—C2—C3108.70 (16)C7—C8—H8115.5
C1—C2—C11125.46 (17)C9—C8—H8115.5
C3—C2—C11125.83 (17)C8—C7—C6129.82 (19)
C4—C3—C2108.81 (16)C8—C7—H7115.1
C4—C3—I2126.53 (14)C6—C7—H7115.1
C2—C3—I2124.62 (13)C5—C6—C7128.80 (19)
C5—C4—C3125.77 (18)C5—C6—H6115.6
C5—C4—C10127.40 (17)C7—C6—H6115.6
C3—C4—C10106.80 (16)C4—C5—C6128.82 (19)
C9—C10—C1125.92 (18)C4—C5—H5115.6
C9—C10—C4127.44 (17)C6—C5—H5115.6
C1—C10—C4106.64 (16)N1—C11—C2179.1 (2)
C10—C9—C8128.76 (19)
C10—C1—C2—C30.1 (2)I1—C1—C10—C4175.27 (13)
I1—C1—C2—C3175.66 (13)C5—C4—C10—C92.5 (3)
C10—C1—C2—C11178.71 (18)C3—C4—C10—C9179.32 (18)
I1—C1—C2—C113.2 (3)C5—C4—C10—C1177.67 (18)
C1—C2—C3—C40.4 (2)C3—C4—C10—C10.5 (2)
C11—C2—C3—C4178.40 (18)C1—C10—C9—C8177.6 (2)
C1—C2—C3—I2178.31 (13)C4—C10—C9—C82.6 (3)
C11—C2—C3—I20.5 (3)C10—C9—C8—C70.4 (4)
C2—C3—C4—C5177.63 (18)C9—C8—C7—C61.5 (4)
I2—C3—C4—C50.2 (3)C8—C7—C6—C51.1 (4)
C2—C3—C4—C100.5 (2)C3—C4—C5—C6178.5 (2)
I2—C3—C4—C10178.39 (13)C10—C4—C5—C60.8 (3)
C2—C1—C10—C9179.57 (18)C7—C6—C5—C40.1 (4)
I1—C1—C10—C94.9 (3)C1—C2—C11—N155 (15)
C2—C1—C10—C40.2 (2)C3—C2—C11—N1123 (15)
Hydrogen-bond geometry (Å, º) top
Cg(C11—N1) is the mid-point of the C11—N1 bond.
D—H···AD—HH···AD···AD—H···A
C8—H8···N1i0.952.623.400 (3)139
C6—H6···Cg(C11—N1)i0.952.763.63 (3)152
Symmetry code: (i) x3/2, y+1/2, z1/2.

Experimental details

Crystal data
Chemical formulaC11H5I2N
Mr404.96
Crystal system, space groupMonoclinic, P21/n
Temperature (K)100
a, b, c (Å)4.2677 (1), 14.9344 (4), 16.7882 (4)
β (°) 96.952 (1)
V3)1062.14 (5)
Z4
Radiation typeMo Kα
µ (mm1)5.88
Crystal size (mm)0.52 × 0.07 × 0.03
Data collection
DiffractometerBruker APEXII CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 2007)
Tmin, Tmax0.150, 0.843
No. of measured, independent and
observed [I > 2σ(I)] reflections
17691, 4616, 3863
Rint0.023
(sin θ/λ)max1)0.809
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.024, 0.058, 1.05
No. of reflections4616
No. of parameters127
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)1.48, 1.32

Computer programs: APEX2 (Bruker, 2007), SAINT (Bruker, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 2012), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top
Cg(C11—N1) is the mid-point of the C11—N1 bond.
D—H···AD—HH···AD···AD—H···A
C8—H8···N1i0.952.623.400 (3)139.1
C6—H6···Cg(C11—N1)i0.952.763.63 (3)152.1
Symmetry code: (i) x3/2, y+1/2, z1/2.
 

Acknowledgements

This work was performed within the Cluster of Excellence Structure Design of Novel High-Performance Materials via Atomic Design and Defect Engineering (ADDE), which is financially supported by the European Union (European Regional Development Fund) and by the Ministry of Science and Art of Saxony (SMWK).

References

First citationAwwadi, F. F., Willett, R. D., Peterson, K. A. & Twamley, B. (2006). Chem. Eur. J. 12, 8952–896.  Web of Science CrossRef PubMed CAS
First citationBruker (2007). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.
First citationDesiraju, G. R. & Steiner, T. (1999). The Weak Hydrogen Bond, pp. 29–123. Oxford University Press.
First citationFarrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854.  Web of Science CrossRef CAS IUCr Journals
First citationFörster, S., Hahn, T., Loose, C., Röder, C., Liebing, S., Seichter, W., Ei\, F., Kortus, J. & Weber, E. (2012). J. Phys. Org. Chem. 25, 856–863.
First citationHussain, Z., Oeser, T. & Hopf, H. (2005). Acta Cryst. E61, o478–o479.  Web of Science CSD CrossRef CAS IUCr Journals
First citationMetrangolo, P., Resnati, G., Pilati, T. & Biella, S. (2008). Struct. Bond. 126, 105–136.  Web of Science CrossRef CAS
First citationNishio, M., Umezawa, Y., Honda, K., Tsuboyama, S. & Suezawa, H. (2009). CrystEngComm, 11, 1757–1788.  Web of Science CrossRef CAS
First citationNozoe, T., Seto, S. & Matsumura, S. (1962). Bull. Chem. Soc. Jpn, 35, 1990–1998.  CrossRef CAS Web of Science
First citationPlattner, P. A. & Pfau, A. S. (1937). Helv. Chim. Acta, 19, 858–879.
First citationRahman, M., Murafuji, T., Kurotobi, K. & Sugihara, Y. (2004). Organometallics, 23, 6176–6183.  CAS
First citationSchmitt, S., Baumgarten, M., Simon, J. & Hafner, K. (1998). Angew. Chem. Int. Ed. 29, 1077–1081.  CrossRef
First citationSheldrick, G. M. (2007). SADABS. University of Göttingen, Germany.
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals
First citationShi, W., Zuo, Z., Deng, C., Shi, C. & Xu, K. (2011). CN Patent No. 102114010.
First citationSuzuka, I. & Yasunami, M. (2008). Jpn Patent No. 2008285435.

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Volume 69| Part 5| May 2013| Pages o654-o655
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