organic compounds
An orthorhombic polymorph of pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile
aDepartment of Chemistry, Capital Normal University, Beijing 100048, People's Republic of China, bResearch Center for Import–Export Chemicals Safety of the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China (AQSIQ), Chinese Academy of Inspection and Quarantine, Beijing 100123, People's Republic of China, and cKey Laboratory of Terahertz Optoelectronics, Ministry of Education, Department of Physics, Capital Normal University, Beijing 100048, People's Republic of China
*Correspondence e-mail: jinqh204@163.com
The title compound, C16H6N6, is a polymorph of the previously reported structure [Kozlov & Goldberg (2008). Acta Cryst. C64, o498–o501]. Unlike the previously reported monoclinic polymorph (space group P21/c, Z = 8), the title compound reveals orthorhombic symmetry (space group Pnma, Z = 4). The molecule shows crystallographic mirror symmetry, while the previously reported structure exhibits two independent molecules per In the title compound, adjacent molecules are essentially parallel along the c axis and tend to be vertical along the b axis with dihedral angles of 72.02 (6)°. However, in the reported polymorph, the entire shows an antiparallel arrangement of adjacent columns related by inversion centers and the two independent molecules are nearly parallel with a dihedral angle of 2.48 (6)°.
Related literature
For ligands based on 1,10-phenanthroline in coordination chemistry, see: Rabaca et al. (2008); Stephenson et al. (2008). For reports of the title compound in coordination chemistry, see: Kulkarni et al. (2004); Stephenson & Hardie (2006); Xiao et al. (2011); Xu et al. (2002). For examples of see: Demirtaş et al. (2011); Jiang et al. (2000); Okabe et al. (2001); Pan & Chen (2009); Ramos Silva et al. (2011); Thallapally et al. (2004). For the previously reported polymorph, see: Kozlov & Goldberg (2008). For related structures, see: Kozlov et al. (2008).
Experimental
Crystal data
|
Data collection: SMART (Bruker, 2007); cell SAINT-Plus (Bruker, 2007); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: SHELXTL.
Supporting information
https://doi.org/10.1107/S1600536811047039/zq2127sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536811047039/zq2127Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S1600536811047039/zq2127Isup3.cml
A mixture of CuCl2.2H2O (0.0178 g, 0.1 mmol) in 5 ml CH2Cl2 and DICNQ (0.0290 g, 0.1 mmol) in 3 ml CH3CN was stirred for 30 min, then a solution of 4,4'-bipyridine (0.0202 g, 0.1 mmol) in 2 ml CH3CN was added under continuous stirring. The resulting solution was refluxed for 5 h and filtered. The filtrate was allowed to evaporate slowly at room temperature to yield yellow block crystals of the title complex. Crystals suitable for single-crystal X-ray diffraction were selected directly from the sample as prepared.
IR (KBr, disc: v/cm-1): 3466.82 s, 1587.57m, 1571.17m, 1505.59m, 1459.84m, 1444.23m, 1384.77m, 1372.26m, 1331.97w, 1264.07w, 1219.29m, 1141.93m, 1123.84w, 1073.56w, 1028.64w, 975.09w, 817.56m, 743.23m, 688.54w, 618.37w, 527.98w, 441.00w, 420.02w, 409.42w.
H atoms were positioned geometrically and refined using a riding model with C—H = 0.93 Å and with Uiso(H) = 1.2Ueq(C).
Ligands based on 1,10-phenanthroline are attractive building blocks for the formation of metal-organic complexes bearing diverse dimensionalities (Rabaca et al., 2008; Stephenson et al., 2008). Among 1,10-phenanthroline derivatives, the DICNQ (DICNQ = pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile) (Xu et al., 2002; Kulkarni et al., 2004) has a big
and multiple coordination including strong chelating phenanthroline ring, bridging pyrazine ring and cyanite groups, so it is good in synthesizing luminescent complexes containing multifunctional ligands. Up to date only a few complexes of DICNQ are reported, such as [Co(dicnq)2Br2] and [Cu(dicnq)2Br2][Cu(dicnq)2Br]Br.(CH3CN).2(H2O) (Stephenson & Hardie, 2006). Very recently, we synthesized five Cu(I) complexes [Cu(PPh3)(C16H6N6)X] (C16H6N6 = pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile; X = Cl, Br, I, CN, SCN) (Xiao et al., 2011). During our attempts to synthesize Cu(II) complexes of DICNQ and 4,4'-bipyridine, we obtained crystals of a new orthorhombic polymorph of the solvent-free DICNQ.Polymorphism can potentially be found in any crystalline material including polymers, minerals, and metals, and is related to allotropy, which refers to elemental solids. When
exists as a result of difference in crystal packing, it is called packing The different crystal types probably are the result of hydration, solvation or the effect of synthesis methods. There are recently reported examples of organic polymorphs: 2-(pyrimidin-2-ylsulfanyl) acetic acid, which is able to form monoclinic and orthorhombic crystals (Ramos Silva et al., 2011; Pan & Chen, 2009). 3,4,5-Trihydroxybenzoic acid monohydrate is found to form three polymorphs (Demirtaş et al., 2011; Jiang et al., 2000; Okabe et al., 2001). We herein report a new orthorhombic polymorph of DICNQ (1).ORTEPIII (Burnett & Johnson, 1996) representation of the title compound (1) is shown in Fig. 1. The title compound belongs to orthorhombic system,
Pnma, consisting of one symmetric unit of single molecule, unlike the reported monoclinic polymorph (space group P21/c), (2), (Kozlov & Goldberg, 2008), which consists of two crystallographically independent molecules.The phenanthroline fragment of both polymorphs is nearly planar, and a similar bending of the cyano groups from the plane of the phenanthroline residues can be observed. The deviating distance of the cyano groups from the plane in (1) (0.182 (7) Å) is obviously bigger than the corresponding deviating distances in (2) (0.0345 Å and 0.0374 Å).
The packing pattern differs from the reported polymorph. In the title compound, there are two packing arrangements (Fig. 2), adjacent molecules are essentially parallel along the c axis and tend to be vertical along the b axis with dihedral angles of 72.02 (6)°. Howerver, in the reported polymorph the entire
shows an antiparallel arrangement of the adjacent columns related by inversion centers, and the two independent molecules are nearly parallel with a dihedral angle of 2.48 (6)°.In addition, the intermolecular assembly of (1) is dominated by π-π stacking of overlaps among phenanthroline fragments and π-π stacking between phenanthroline fragment and cyano group of adjacent molecules (Fig. 2), with an interplanar distance between the parallel phenanthroline rings in the two adjacent molecules of 3.030 (1) Å. In contrast, in (2) and the ethanol solvate of DICNQ (C16H6N6).(C2H6O) (3) (Kozlov et al., 2008), adjacent molecules overlap only through their phenanthroline fragments with the shortest interplanar distance of 3.380 (3) Å for (2), 3.27 Å and 3.40 Å for (3).
Various methods and conditions of the crystallization process are the main reason responsible for the formation of different polymorphic forms (Thallapally et al., 2004). The two polymorphs (1) and (2) are prepared under different catalysts. (1) was prepared under the catalysis of CuCl2.2H2O and 4,4'-bipy, while (2) was prepared under the catalysis of [Pd(PPh3)Cl2].
For ligands based on 1,10-phenanthroline in coordination chemistry, see: Rabaca et al. (2008); Stephenson et al. (2008). For reports of the title compound in coordination chemistry, see: Kulkarni et al. (2004); Stephenson & Hardie (2006); Xiao et al. (2011); Xu et al. (2002). For examples of
see: Demirtaş et al. (2011); Jiang et al. (2000); Okabe et al. (2001); Pan & Chen (2009); Ramos Silva et al. (2011); Thallapally et al. (2004). For the previously reported polymorph, see: Kozlov & Goldberg (2008). For related structures, see: Kozlov et al. (2008).Data collection: SMART (Bruker, 2007); cell
SAINT-Plus (Bruker, 2007); data reduction: SAINT-Plus (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).Fig. 1. Perspective view of a basic unit of the title complex. Atoms are displayed as elliposoids at the 50% probability level at ca 293 K. | |
Fig. 2. The crystal packing of the title complex. |
C16H6N6 | F(000) = 576 |
Mr = 282.27 | Dx = 1.544 Mg m−3 |
Orthorhombic, Pnma | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ac 2n | Cell parameters from 1184 reflections |
a = 14.1055 (13) Å | θ = 2.9–27.5° |
b = 16.3331 (14) Å | µ = 0.10 mm−1 |
c = 5.2694 (4) Å | T = 293 K |
V = 1214.00 (18) Å3 | Block, yellow |
Z = 4 | 0.45 × 0.30 × 0.26 mm |
Bruker SMART CCD area-detector diffractometer | 1113 independent reflections |
Radiation source: fine-focus sealed tube | 759 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.046 |
phi and ω scans | θmax = 25.0°, θmin = 2.9° |
Absorption correction: multi-scan (SADABS; Bruker, 2007) | h = −16→16 |
Tmin = 0.956, Tmax = 0.974 | k = −19→7 |
4543 measured reflections | l = −6→6 |
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)] = 0.041 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.119 | H-atom parameters constrained |
S = 1.06 | w = 1/[σ2(Fo2) + (0.0556P)2 + 0.3018P] where P = (Fo2 + 2Fc2)/3 |
1113 reflections | (Δ/σ)max < 0.001 |
100 parameters | Δρmax = 0.20 e Å−3 |
0 restraints | Δρmin = −0.24 e Å−3 |
C16H6N6 | V = 1214.00 (18) Å3 |
Mr = 282.27 | Z = 4 |
Orthorhombic, Pnma | Mo Kα radiation |
a = 14.1055 (13) Å | µ = 0.10 mm−1 |
b = 16.3331 (14) Å | T = 293 K |
c = 5.2694 (4) Å | 0.45 × 0.30 × 0.26 mm |
Bruker SMART CCD area-detector diffractometer | 1113 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2007) | 759 reflections with I > 2σ(I) |
Tmin = 0.956, Tmax = 0.974 | Rint = 0.046 |
4543 measured reflections |
R[F2 > 2σ(F2)] = 0.041 | 0 restraints |
wR(F2) = 0.119 | H-atom parameters constrained |
S = 1.06 | Δρmax = 0.20 e Å−3 |
1113 reflections | Δρmin = −0.24 e Å−3 |
100 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
N1 | 0.56932 (11) | 0.33317 (10) | −0.1078 (3) | 0.0347 (5) | |
N2 | 0.77953 (11) | 0.33585 (9) | 0.6140 (3) | 0.0322 (4) | |
N3 | 0.92249 (13) | 0.37680 (13) | 1.1146 (4) | 0.0539 (6) | |
C1 | 0.61818 (12) | 0.29508 (11) | 0.0786 (3) | 0.0279 (5) | |
C2 | 0.67134 (12) | 0.33802 (11) | 0.2603 (3) | 0.0281 (5) | |
C3 | 0.67273 (13) | 0.42373 (12) | 0.2476 (4) | 0.0349 (5) | |
H3 | 0.7060 | 0.4542 | 0.3673 | 0.042* | |
C4 | 0.62440 (14) | 0.46176 (13) | 0.0564 (4) | 0.0381 (6) | |
H4 | 0.6249 | 0.5185 | 0.0422 | 0.046* | |
C5 | 0.57451 (13) | 0.41428 (12) | −0.1161 (4) | 0.0369 (5) | |
H5 | 0.5426 | 0.4410 | −0.2463 | 0.044* | |
C6 | 0.72648 (12) | 0.29328 (11) | 0.4470 (3) | 0.0285 (5) | |
C7 | 0.83106 (12) | 0.29288 (12) | 0.7773 (4) | 0.0317 (5) | |
C8 | 0.88437 (14) | 0.33918 (13) | 0.9640 (4) | 0.0372 (5) |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0333 (9) | 0.0368 (10) | 0.0339 (10) | 0.0021 (7) | −0.0025 (8) | 0.0040 (8) |
N2 | 0.0305 (9) | 0.0357 (9) | 0.0303 (9) | −0.0020 (7) | 0.0014 (8) | −0.0007 (8) |
N3 | 0.0476 (11) | 0.0703 (14) | 0.0437 (12) | −0.0084 (10) | −0.0041 (10) | −0.0142 (11) |
C1 | 0.0249 (9) | 0.0318 (10) | 0.0271 (11) | 0.0011 (8) | 0.0041 (8) | 0.0010 (9) |
C2 | 0.0255 (9) | 0.0291 (10) | 0.0296 (11) | 0.0002 (8) | 0.0036 (8) | 0.0018 (9) |
C3 | 0.0335 (11) | 0.0312 (10) | 0.0401 (13) | −0.0031 (9) | −0.0007 (10) | −0.0031 (10) |
C4 | 0.0353 (11) | 0.0302 (10) | 0.0488 (14) | 0.0018 (9) | 0.0026 (11) | 0.0059 (10) |
C5 | 0.0354 (11) | 0.0370 (12) | 0.0382 (12) | 0.0052 (9) | −0.0005 (10) | 0.0082 (10) |
C6 | 0.0253 (9) | 0.0319 (9) | 0.0283 (10) | −0.0016 (8) | 0.0028 (8) | −0.0029 (8) |
C7 | 0.0264 (10) | 0.0428 (11) | 0.0261 (11) | −0.0027 (8) | 0.0008 (9) | −0.0014 (9) |
C8 | 0.0314 (11) | 0.0480 (13) | 0.0321 (12) | −0.0018 (9) | 0.0013 (10) | −0.0013 (11) |
N1—C5 | 1.327 (3) | C3—C4 | 1.366 (3) |
N1—C1 | 1.352 (2) | C3—H3 | 0.9300 |
N2—C7 | 1.327 (2) | C4—C5 | 1.387 (3) |
N2—C6 | 1.348 (2) | C4—H4 | 0.9300 |
N3—C8 | 1.138 (3) | C5—H5 | 0.9300 |
C1—C2 | 1.404 (2) | C6—C6i | 1.414 (4) |
C1—C1i | 1.473 (4) | C7—C7i | 1.401 (4) |
C2—C3 | 1.402 (3) | C7—C8 | 1.451 (3) |
C2—C6 | 1.451 (2) | ||
C5—N1—C1 | 117.07 (17) | C3—C4—H4 | 120.6 |
C7—N2—C6 | 117.02 (16) | C5—C4—H4 | 120.6 |
N1—C1—C2 | 122.55 (17) | N1—C5—C4 | 124.37 (19) |
N1—C1—C1i | 117.41 (10) | N1—C5—H5 | 117.8 |
C2—C1—C1i | 119.97 (11) | C4—C5—H5 | 117.8 |
C3—C2—C1 | 118.29 (17) | N2—C6—C6i | 121.05 (10) |
C3—C2—C6 | 121.85 (17) | N2—C6—C2 | 118.69 (16) |
C1—C2—C6 | 119.80 (17) | C6i—C6—C2 | 120.23 (10) |
C4—C3—C2 | 118.85 (18) | N2—C7—C7i | 121.93 (10) |
C4—C3—H3 | 120.6 | N2—C7—C8 | 116.61 (17) |
C2—C3—H3 | 120.6 | C7i—C7—C8 | 121.41 (11) |
C3—C4—C5 | 118.85 (18) | N3—C8—C7 | 177.0 (2) |
C5—N1—C1—C2 | 1.0 (3) | C3—C4—C5—N1 | 0.7 (3) |
C5—N1—C1—C1i | −175.87 (13) | C7—N2—C6—C6i | −0.18 (19) |
N1—C1—C2—C3 | 0.5 (3) | C7—N2—C6—C2 | −178.16 (15) |
C1i—C1—C2—C3 | 177.37 (12) | C3—C2—C6—N2 | 0.7 (3) |
N1—C1—C2—C6 | −176.57 (15) | C1—C2—C6—N2 | 177.73 (15) |
C1i—C1—C2—C6 | 0.26 (19) | C3—C2—C6—C6i | −177.26 (13) |
C1—C2—C3—C4 | −1.5 (3) | C1—C2—C6—C6i | −0.26 (19) |
C6—C2—C3—C4 | 175.52 (17) | C6—N2—C7—C7i | 0.18 (19) |
C2—C3—C4—C5 | 1.0 (3) | C6—N2—C7—C8 | −177.14 (15) |
C1—N1—C5—C4 | −1.7 (3) |
Symmetry code: (i) x, −y+1/2, z. |
Experimental details
Crystal data | |
Chemical formula | C16H6N6 |
Mr | 282.27 |
Crystal system, space group | Orthorhombic, Pnma |
Temperature (K) | 293 |
a, b, c (Å) | 14.1055 (13), 16.3331 (14), 5.2694 (4) |
V (Å3) | 1214.00 (18) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.10 |
Crystal size (mm) | 0.45 × 0.30 × 0.26 |
Data collection | |
Diffractometer | Bruker SMART CCD area-detector |
Absorption correction | Multi-scan (SADABS; Bruker, 2007) |
Tmin, Tmax | 0.956, 0.974 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4543, 1113, 759 |
Rint | 0.046 |
(sin θ/λ)max (Å−1) | 0.595 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.041, 0.119, 1.06 |
No. of reflections | 1113 |
No. of parameters | 100 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.20, −0.24 |
Computer programs: SMART (Bruker, 2007), SAINT-Plus (Bruker, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008) and ORTEPIII (Burnett & Johnson, 1996), SHELXTL (Sheldrick, 2008).
Acknowledgements
This work was supported by the National Natural Science Foundation of China (No. 21171119). It was granted by the research project of recycling PET of food contact materials (No. 2010 J K022) from the Chinese Academy of Inspection and Quarantine, National Keystone Basic Research Program (973 Program) under grant Nos. 2007CB310408 and 2006CB302901, and the Funding Project for Academic Human Resources Development in Institutions of Higher Learning Under the Jurisdiction of Beijing Municipality.
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Ligands based on 1,10-phenanthroline are attractive building blocks for the formation of metal-organic complexes bearing diverse dimensionalities (Rabaca et al., 2008; Stephenson et al., 2008). Among 1,10-phenanthroline derivatives, the DICNQ (DICNQ = pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile) (Xu et al., 2002; Kulkarni et al., 2004) has a big conjugated system and multiple coordination including strong chelating phenanthroline ring, bridging pyrazine ring and cyanite groups, so it is good in synthesizing luminescent complexes containing multifunctional ligands. Up to date only a few complexes of DICNQ are reported, such as [Co(dicnq)2Br2] and [Cu(dicnq)2Br2][Cu(dicnq)2Br]Br.(CH3CN).2(H2O) (Stephenson & Hardie, 2006). Very recently, we synthesized five Cu(I) complexes [Cu(PPh3)(C16H6N6)X] (C16H6N6 = pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile; X = Cl, Br, I, CN, SCN) (Xiao et al., 2011). During our attempts to synthesize Cu(II) complexes of DICNQ and 4,4'-bipyridine, we obtained crystals of a new orthorhombic polymorph of the solvent-free DICNQ.
Polymorphism can potentially be found in any crystalline material including polymers, minerals, and metals, and is related to allotropy, which refers to elemental solids. When polymorphism exists as a result of difference in crystal packing, it is called packing polymorphism. The different crystal types probably are the result of hydration, solvation or the effect of synthesis methods. There are recently reported examples of organic polymorphs: 2-(pyrimidin-2-ylsulfanyl) acetic acid, which is able to form monoclinic and orthorhombic crystals (Ramos Silva et al., 2011; Pan & Chen, 2009). 3,4,5-Trihydroxybenzoic acid monohydrate is found to form three polymorphs (Demirtaş et al., 2011; Jiang et al., 2000; Okabe et al., 2001). We herein report a new orthorhombic polymorph of DICNQ (1).
ORTEPIII (Burnett & Johnson, 1996) representation of the title compound (1) is shown in Fig. 1. The title compound belongs to orthorhombic system, space group Pnma, consisting of one symmetric unit of single molecule, unlike the reported monoclinic polymorph (space group P21/c), (2), (Kozlov & Goldberg, 2008), which consists of two crystallographically independent molecules.
The phenanthroline fragment of both polymorphs is nearly planar, and a similar bending of the cyano groups from the plane of the phenanthroline residues can be observed. The deviating distance of the cyano groups from the plane in (1) (0.182 (7) Å) is obviously bigger than the corresponding deviating distances in (2) (0.0345 Å and 0.0374 Å).
The packing pattern differs from the reported polymorph. In the title compound, there are two packing arrangements (Fig. 2), adjacent molecules are essentially parallel along the c axis and tend to be vertical along the b axis with dihedral angles of 72.02 (6)°. Howerver, in the reported polymorph the entire crystal structure shows an antiparallel arrangement of the adjacent columns related by inversion centers, and the two independent molecules are nearly parallel with a dihedral angle of 2.48 (6)°.
In addition, the intermolecular assembly of (1) is dominated by π-π stacking of overlaps among phenanthroline fragments and π-π stacking between phenanthroline fragment and cyano group of adjacent molecules (Fig. 2), with an interplanar distance between the parallel phenanthroline rings in the two adjacent molecules of 3.030 (1) Å. In contrast, in (2) and the ethanol solvate of DICNQ (C16H6N6).(C2H6O) (3) (Kozlov et al., 2008), adjacent molecules overlap only through their phenanthroline fragments with the shortest interplanar distance of 3.380 (3) Å for (2), 3.27 Å and 3.40 Å for (3).
Various methods and conditions of the crystallization process are the main reason responsible for the formation of different polymorphic forms (Thallapally et al., 2004). The two polymorphs (1) and (2) are prepared under different catalysts. (1) was prepared under the catalysis of CuCl2.2H2O and 4,4'-bipy, while (2) was prepared under the catalysis of [Pd(PPh3)Cl2].