6,6'-(Pyridine-2,6-di-yl)bis-(pyrrolo-[3,4-b]pyridine-5,7-dione).

Abstract

The title compound, C(19)H(9)N(5)O(4), has crystallographically imposed twofold rotational symmetry. The asymmetric unit contains one half-mol-ecule. The crystal structure is stabilized by π-π stacking of inversion-related pyrrolo-[3,4-b]pyridine rings, with a centroid-centroid distance between stacked pyridines of 3.6960 (8) Å. The dihedral angle between the central pyridine ring and the pyrrolo-pyridine side rings is 77.86 (2)° while the angle between the two side chains is 60.87 (2)°.

Full text

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6,60 0 0-(Pyridine-2,6-diyl)bis(pyrrolo[3,4-b]-
pyridine-5,7-dione)
P. C. W. Van der Berg,* Hendrik G. Visser and Andreas
Roodt
Department of Chemistry, University of the Free State, PO Box 339, Bloemfontein
9300, South Africa
Correspondence e-mail: vanderbergpcw@ufs.ac.za
Received 5 October 2011; accepted 24 October 2011
Key indicators: single-crystal X-ray study; T = 100 K; mean ?(C–C) = 0.002 A ˚;
R factor = 0.034; wR factor = 0.091; data-to-parameter ratio = 15.0.
The title compound, C19H9N5O4, has crystallographically
imposed twofold rotational symmetry. The asymmetric unit
contains one half-molecule. The crystal structure is stabilized
by ?–? stacking of inversion-related pyrrolo[3,4-b]pyridine
rings, with a centroid–centroid distance between stacked
pyridines of 3.6960 (8) A˚. The dihedral angle between the
central pyridine ring and the pyrrolo-pyridine side rings is
77.86 (2)?while the angle between the two side chains is
60.87 (2)?.
Related literature
For related structures, see: Jain et al. (2004). For related metal
complexes, see: Schutte et al. (2009, 2010); Brink et al. (2011).
Experimental
Crystal data
C19H9N5O4
Mr= 371.31
Monoclinic, C2=c
a = 14.539 (1) A˚
b = 7.391 (1) A˚
c = 15.686 (1) A˚
? = 108.752 (2)?
V = 1596.1 (3) A˚3
Z = 4
Mo K? radiation
? = 0.11 mm?1
T = 100 K
0.34 ? 0.29 ? 0.27 mm
Data collection
Bruker X8 APEXII 4K KappaCCD
diffractometer
Absorption correction: multi-scan
(SADABS; Bruker, 2004)
Tmin= 0.681, Tmax= 0.746
12803 measured reflections
1920 independent reflections
1717 reflections with I > 2?(I)
Rint= 0.024
Refinement
R[F2> 2?(F2)] = 0.034
wR(F2) = 0.091
S = 1.06
1920 reflections
128 parameters
H-atom parameters constrained
??max= 0.31 e A˚?3
??min= ?0.21 e A˚?3
Data collection: APEX2 (Bruker, 2010); cell refinement: SAINT-
Plus (Bruker, 2004); data reduction: SAINT-Plus; program(s) used to
solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to
refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics:
DIAMOND (Brandenburg & Putz, 2005); software used to prepare
material for publication: WinGX (Farrugia, 1999).
The Research fund of the University of the Free State, the
NRF and NTembi are thankfully acknowledged for funding.
Supplementary data and figures for this paper are available from the
IUCr electronic archives (Reference: PK2352).
References
Brandenburg, K. & Putz, H. (2005). DIAMOND. Crystal Impact GbR, Bonn,
Germany.
Brink, A., Visser, H. G. & Roodt, A. (2011). Acta Cryst. E67, m34–m35.
Bruker (2004). SAINT-Plus and SADABS. Bruker AXS Inc., Madison,
Wisconsin, USA.
Bruker (2010). APEX2. Bruker AXS Inc., Madison, Wisconsin, USA.
Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838.
Jain, S. L., Bhattacharyya, P., Milton, H. L., Slawin, A. M. Z., Crayston, J. A. &
Woollins, J. D. (2004). Dalton Trans. pp. 862–871.
Schutte, M., Visser, H. G. & Brink, A. (2009). Acta Cryst. E65, m1575–m1576.
Schutte, M., Visser, H. G. & Roodt, A. (2010). Acta Cryst. E66, m859–m860.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.
organic compounds
o3130
Van der Berg et al.
doi:10.1107/S160053681104414X
Acta Cryst. (2011). E67, o3130
Acta Crystallographica Section E
Structure Reports
Online
ISSN 1600-5368

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supplementary materials

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supplementary materials
sup-1
Acta Cryst. (2011). E67, o3130 [ doi:10.1107/S160053681104414X ]
6,6'-(Pyridine-2,6-diyl)bis(pyrrolo[3,4-b]pyridine-5,7-dione)
P. C. W. Van der Berg, H. G. Visser and A. Roodt
Comment
The title compound was synthesized as a ligand for potential use in medical and radiopharmaceutical applications (Schutte
et al., 2009; Schutte et al., 2010; Brink et al., 2011).
The title compound, C19H9N5O4, has crystallographically imposed two-fold rotational symmetry. The asymmetric unit
contains one half-molecule with C1, H1 and N1 lying on a two-fold rotational axis. The dihedral angle between the central
pyridine ring and the pyrrolo-pyridine side rings is 77.86 (2)° while the angle between the two side chains is 60.87 (2)°.
In the crystal, all bond distances and angles are normal (Jain et al. (2004). The molecules pack in layers, diagonally across
the ac plane in a head-to-tail fashion and the structure is stabilized by π-π stacking between the outlying pyridine rings of
inversion-related structures. The centroid to centroid distances between these stacked rings = 3.6960 (8) Å (see Fig. 2).
Experimental
Under oxygen atmosphere: 2,3-pyridinedicarboxylic acid (1.000 g, 5.982 mmol) was added as a solid in one portion to a
suspension of 2,6-diaminopyridine (0.3092 g, 2.833 mmol) in pyridine (10 ml) and the mixture was stirred at 40 °C for 40
min. Triphenylphosphite (10 ml) was added dropwise over 10 minutes after which the temperature was increased to 90–100
°C and stirred for a further 24 h. On cooling the precipitate was filtered, washed with H2O (50 ml) and then MeOH (50 ml).
The precipitate was recrystallized in chloroform to obtain colourless crystals after five days.
Refinement
The aromatic H atoms were placed in geometrically idealized positions at C—H = 0.93 Å, respectively and constrained to
ride on their parent atoms, with Uiso(H) = 1.2Ueq(C). The highest peak is located 0.67 Å from C5 and the deepest hole is
situated 1.26 Å from C1
Figures
Fig. 1. Molecular structure of the title compound. Displacement ellipsoids are drawn at the
50% probability level. Unlabelled atoms are related to their labelled counterparts by a crystal-
lographic 2-fold rotation about b.
Fig. 2. Packing and illustration of π-π stacking in the crystal.

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supplementary materials
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6,6'-(Pyridine-2,6-diyl)bis(pyrrolo[3,4-b]pyridine-5,7-dione)
Crystal data
C19H9N5O4
F(000) = 760
Dx = 1.545 Mg m−3
Mo Kα radiation, λ = 0.71073 Å
Cell parameters from 6738 reflections
θ = 2.7–28.3°
µ = 0.11 mm−1
T = 100 K
Mr = 371.31
Monoclinic, C2/c
a = 14.539 (1) Å
b = 7.391 (1) Å
c = 15.686 (1) Å
β = 108.752 (2)°
V = 1596.1 (3) Å3
Z = 4
Cuboid, colourless
0.34 × 0.29 × 0.27 mm
Data collection
Bruker X8 APEXII 4K KappaCCD
diffractometer
Radiation source: fine-focus sealed tube
graphite
ω and φ scans
Absorption correction: multi-scan
(SADABS; Bruker, 2004)
Tmin = 0.681, Tmax = 0.746
12803 measured reflections
1920 independent reflections
1717 reflections with I > 2σ(I)
Rint = 0.024
θmax = 28°, θmin = 3.1°
h = −19→15
k = −9→9
l = −20→20
Refinement
Refinement on F2
Primary atom site location: structure-invariant direct
methods
Secondary atom site location: difference Fourier map
Hydrogen site location: inferred from neighbouring
sites
Least-squares matrix: full
R[F2 > 2σ(F2)] = 0.034
wR(F2) = 0.091
H-atom parameters constrained
S = 1.06
w = 1/[σ2(Fo2) + (0.0432P)2 + 1.2599P]
where P = (Fo2 + 2Fc2)/3
(Δ/σ)max < 0.001
Δρmax = 0.31 e Å−3
Δρmin = −0.21 e Å−3
1920 reflections
128 parameters
0 restraints
Special details
Experimental. The intensity data were collected on a Bruker X8 ApexII 4 K Kappa CCD diffractometer using an exposure time of 30
s/frame. A total of 1758 frames were collected with a frame width of 0.5° covering up to θ = 28.00° with 99.3% completeness accom-
plished.

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supplementary materials
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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)
x
−0.05122 (6)
0.22325 (6)
0
0.07684 (7)
0.07688 (7)
0.17897 (8)
0.02795 (8)
0.15034 (8)
0.1419
0.16835 (8)
0.09539 (8)
0.25407 (8)
0.3115
0.23809 (8)
0.2863
0.03783 (8)
0.04021 (8)
0.0678
0
0
y
0.18475 (11)
0.31769 (14)
0.22247 (19)
0.22769 (13)
0.39842 (13)
0.39008 (15)
0.24566 (15)
0.48687 (16)
0.5224
0.31349 (16)
0.35189 (15)
0.48175 (16)
0.5102
0.52873 (16)
0.5884
0.12612 (16)
−0.06106 (16)
−0.1208
−0.1562 (2)
−0.282
z
0.00789 (5)
0.24267 (6)
0.25
0.13958 (6)
−0.07379 (6)
0.08242 (7)
0.04720 (7)
−0.09009 (8)
−0.149
0.16665 (8)
0.01192 (7)
0.06507 (8)
0.1104
−0.02460 (8)
−0.0407
0.19763 (7)
0.19451 (7)
0.1565
0.25
0.25
Uiso*/Ueq
0.0226 (2)
0.0327 (2)
0.0206 (3)
0.0209 (2)
0.0212 (2)
0.0210 (2)
0.0186 (2)
0.0231 (2)
0.028*
0.0232 (2)
0.0184 (2)
0.0249 (3)
0.03*
0.0246 (3)
0.029*
0.0205 (2)
0.0228 (2)
0.027*
0.0237 (3)
0.028*
O1
O2
N1
N2
N3
C7
C4
C10
H10
C6
C5
C8
H8
C9
H9
C3
C2
H2
C1
H1
Atomic displacement parameters (Å2)
U11
0.0175 (4)
0.0241 (5)
0.0173 (6)
0.0179 (5)
0.0210 (5)
0.0184 (5)
0.0182 (5)
0.0250 (6)
0.0189 (5)
0.0162 (5)
0.0177 (5)
U22
0.0269 (4)
0.0474 (6)
0.0254 (7)
0.0265 (5)
0.0210 (5)
0.0217 (5)
0.0193 (5)
0.0208 (5)
0.0268 (6)
0.0176 (5)
0.0251 (6)
U33
0.0224 (4)
0.0219 (4)
0.0177 (6)
0.0180 (4)
0.0226 (5)
0.0223 (5)
0.0187 (5)
0.0262 (5)
0.0230 (5)
0.0221 (5)
0.0306 (6)
U12
−0.0041 (3)
−0.0071 (4)
0
−0.0026 (4)
0.0000 (4)
0.0000 (4)
0.0010 (4)
0.0007 (4)
−0.0019 (4)
0.0005 (4)
−0.0027 (4)
U13
0.0052 (3)
0.0010 (4)
0.0037 (5)
0.0053 (4)
0.0084 (4)
0.0059 (4)
0.0064 (4)
0.0120 (5)
0.0053 (4)
0.0070 (4)
0.0062 (5)
U23
−0.0019 (3)
−0.0015 (4)
0
−0.0012 (4)
−0.0002 (4)
−0.0032 (4)
−0.0017 (4)
0.0008 (4)
−0.0033 (4)
−0.0027 (4)
−0.0037 (5)
O1
O2
N1
N2
N3
C7
C4
C10
C6
C5
C8