organic compounds
A second monoclinic polymorph of 2,9-dimethyl-1,10-phenanthroline dihydrate
aDepartment of Physics, Faculty of Arts and Sciences, University of Ondokuz Mayıs, Kurupelit 55139, Samsun, Turkey, and bSchool of Natural Sciences (Chemistry), Bedson Building, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU, England
*Correspondence e-mail: w.clegg@ncl.ac.uk
A second monoclinic polymorph of the title compound, neocuproine dihydrate, C14H12N2·2H2O, is reported. Unlike the first polymorph [Baggio, Baggio & Mombrú (1998). Acta Cryst. C54, 1900–1902], in which the phenanthroline ring system was constrained to lie in a crystallographic mirror plane, here there is no such imposed symmetry. Consequently, the molecule shows small deviations from planarity, the outer rings being twisted slightly in opposite directions from the plane of the central ring. The hydrogen-bonding motifs remain essentially the same as in the first polymorph, involving small rings of four water molecules and large rings containing four water molecules and two neocuproine molecules, but with no H-atom disorder for the water molecules in this case. There are also aromatic π–π stacking interactions.
Comment
In our ongoing research on squaric acid, we have synthesized some mixed-ligand metal complexes of squaric acid and their structures have been reported (Uçar et al., 2004, 2005; Bulut et al., 2004). We have used such co-ligands as isonicotinamide and 2,9-dimethyl-1,10-phenanthrolione (neocuproine) in our research and, while synthesizing an iron complex of squaric acid and neocuproine, we obtained crystals of neocuproine dihydrate, (I), as a side product. A search of the Cambridge Structural Database (CSD, Version 5.26 plus three updates; Allen, 2002) did not find a match, and it was only by carrying out a structure-based search that we found that a structure of the same compound, also as a dihydrate, had previously been reported (Baggio et al., 1998). The of a hemihydrate has also been determined (Britton et al., 1991). A unit-cell determination with our sample at 298 K gave essentially the same parameters as were determined at 150 K, with the expected slight expansion, and so we are confident that we are reporting the of a second monoclinic polymorph of (I), and not the result of a at low temperature.
This second monoclinic polymorph of (I), shown in Fig. 1, crystallizes in C2/c with all atoms lying in general positions. Britton et al. (1991) reported some slight tilting of the individual six-membered rings with respect to one another within the phenanthroline system in the hemihydrate. Baggio et al. (1998) reported that the molecule was exactly planar in the first polymorph of the dihydrate, as a consequence of crystallographic mirror symmetry. A least-squares plane fitted through all non-H atoms of the phenathroline skeleton of (I) has an r.m.s. deviation of 0.024 Å, and the dihedral angle between two mean planes fitted through the outermost rings is 2.37 (2)°, indicating a small deviation of the molecule from planarity. This distortion consists mainly of a twist of the outer rings in opposite directions out of the plane of the central ring, as indicated by the N1—C12—C11—N2 torsion angle of −2.8 (3)°, almost the same as the above dihedral angle.
The overall crystal packing of (I) is similar to that in the first monoclinic polymorph, albeit without the perfectly planar sheets achieved by imposed mirror symmetry. In the first polymorph, H-atom disorder in the water molecules means there is more than one possible orientation of each water molecule and hence some uncertainty about the hydrogen-bonding arrangement. In (I), all H atoms were easily and convincingly located in a difference map and water H atoms were freely refined. The hydrogen-bonding arrangement is shown in Fig. 2. The water molecules form hydrogen bonds around an inversion centre to generate a square R44(8) motif (Bernstein et al., 1995). A second large R66(18) motif links two neocuproine molecules together via the water molecules.
Unlike the first polymorph, we find no evidence of weak C—H⋯O hydrogen bonding here. However, the separations between parallel neocuproine molecules stacked along the b axis are alternately 3.32 and 3.39 Å, and each molecule has approximately a half-ring overlap with the next molecule in the stack, characteristic of aromatic π–π interactions.
Experimental
Squaric acid, H2Sq (0.57 g, 5 mmol) dissolved in water (25 ml) was neutralized with NaOH (0.40 g, 10 mmol) and the mixture was added to a hot solution of FeCl2·6H2O (1.17 g, 5 mmol) dissolved in water (50 ml). The mixture was stirred at 333 K for 12 h and then cooled to room temperature. The brown crystals that formed were filtered off, washed with water and ethanol, and dried in vacuo. A solution of 2,9-dimethyl-1,10-phenanthroline (0.435 g, 2 mmol) in methanol (50 ml) was added dropwise with stirring to a suspension of FeSq·2H2O (0.21 g, 1 mmol) in water (50 ml). The brown solution was refluxed for about 2 h and then cooled to room temperature. A few days later, brown crystals of the desired Fe complex had formed, along with some well formed colourless crystals of (I) as a side-product.
Crystal data
|
Data collection
Refinement
|
All H atoms were located in a difference Fourier map. Water H atoms were freely refined, giving O—H distances shown in Table 1. Other H atoms were treated as riding, with Uiso(H) = 1.2Ueq(C) and C—H = 0.95 Å for aromatic, and Uiso(H) = 1.5Ueq(C) and C—H = 0.98 Å for methyl groups.
Data collection: SMART (Bruker, 2001); cell SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2001); program(s) used to refine structure: SHELXTL; molecular graphics: DIAMOND (Brandenburg & Putz, 2004); software used to prepare material for publication: SHELXTL and local programs.
Supporting information
https://doi.org/10.1107/S1600536805033179/bt6763sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536805033179/bt6763Isup2.hkl
Data collection: SMART (Bruker, 2001); cell
SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2001); program(s) used to refine structure: SHELXTL; molecular graphics: DIAMOND (Brandenburg & Putz, 2004); software used to prepare material for publication: SHELXTL and local programs.C14H12N2·2H2O | F(000) = 1040 |
Mr = 244.29 | Dx = 1.301 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2yc | Cell parameters from 6879 reflections |
a = 22.942 (2) Å | θ = 2.4–28.8° |
b = 6.7388 (7) Å | µ = 0.09 mm−1 |
c = 17.9594 (18) Å | T = 150 K |
β = 116.019 (2)° | Block, colourless |
V = 2495.2 (4) Å3 | 0.61 × 0.38 × 0.21 mm |
Z = 8 |
Bruker SMART 1K CCD area-detector diffractometer | 2191 independent reflections |
Radiation source: sealed tube | 1781 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.029 |
Thin–slice ω scans | θmax = 25.0°, θmin = 2.0° |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | h = −27→27 |
Tmin = 0.928, Tmax = 0.982 | k = −7→8 |
8619 measured reflections | l = −21→21 |
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)] = 0.062 | Hydrogen site location: difference Fourier map |
wR(F2) = 0.154 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.22 | w = 1/[σ2(Fo2) + (0.0516P)2 + 4.5458P] where P = (Fo2 + 2Fc2)/3 |
2191 reflections | (Δ/σ)max < 0.001 |
181 parameters | Δρmax = 0.27 e Å−3 |
0 restraints | Δρmin = −0.26 e Å−3 |
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. |
x | y | z | Uiso*/Ueq | ||
O1 | 0.19573 (11) | 0.4772 (4) | −0.01527 (15) | 0.0406 (6) | |
H1O | 0.1883 (16) | 0.553 (6) | 0.017 (2) | 0.055 (11)* | |
H2O | 0.1861 (18) | 0.355 (7) | −0.009 (2) | 0.073 (13)* | |
O2 | 0.17540 (10) | 0.0684 (3) | −0.00899 (12) | 0.0335 (5) | |
H3O | 0.1572 (17) | −0.035 (6) | 0.002 (2) | 0.055 (11)* | |
H4O | 0.2143 (16) | 0.022 (5) | 0.0011 (18) | 0.038 (9)* | |
N1 | 0.08861 (9) | 0.7549 (3) | 0.00743 (12) | 0.0206 (5) | |
N2 | 0.20798 (9) | 0.7166 (3) | 0.13865 (12) | 0.0190 (5) | |
C1 | 0.03091 (11) | 0.7632 (4) | −0.05702 (15) | 0.0239 (6) | |
C2 | −0.02721 (12) | 0.7565 (4) | −0.04881 (16) | 0.0299 (6) | |
H2 | −0.0678 | 0.7609 | −0.0966 | 0.036* | |
C3 | −0.02506 (12) | 0.7436 (4) | 0.02798 (16) | 0.0283 (6) | |
H3 | −0.0640 | 0.7420 | 0.0344 | 0.034* | |
C4 | 0.03580 (11) | 0.7325 (4) | 0.09819 (16) | 0.0243 (6) | |
C5 | 0.04243 (12) | 0.7185 (4) | 0.18106 (16) | 0.0301 (6) | |
H5 | 0.0046 | 0.7160 | 0.1901 | 0.036* | |
C6 | 0.10114 (13) | 0.7087 (4) | 0.24644 (16) | 0.0301 (6) | |
H6 | 0.1042 | 0.7012 | 0.3009 | 0.036* | |
C7 | 0.15925 (12) | 0.7094 (4) | 0.23481 (15) | 0.0225 (6) | |
C8 | 0.22152 (12) | 0.6992 (4) | 0.30111 (15) | 0.0256 (6) | |
H8 | 0.2268 | 0.6918 | 0.3565 | 0.031* | |
C9 | 0.27443 (12) | 0.6998 (4) | 0.28505 (16) | 0.0254 (6) | |
H9 | 0.3168 | 0.6953 | 0.3295 | 0.030* | |
C10 | 0.26627 (11) | 0.7072 (3) | 0.20277 (15) | 0.0204 (5) | |
C11 | 0.15525 (11) | 0.7208 (3) | 0.15433 (14) | 0.0191 (5) | |
C12 | 0.09161 (11) | 0.7366 (3) | 0.08391 (14) | 0.0200 (5) | |
C13 | 0.03040 (12) | 0.7823 (5) | −0.14102 (15) | 0.0337 (7) | |
H13A | 0.0561 | 0.8982 | −0.1414 | 0.051* | |
H13B | −0.0143 | 0.7986 | −0.1835 | 0.051* | |
H13C | 0.0491 | 0.6625 | −0.1528 | 0.051* | |
C14 | 0.32325 (11) | 0.7054 (4) | 0.18304 (16) | 0.0272 (6) | |
H14A | 0.3246 | 0.5786 | 0.1571 | 0.041* | |
H14B | 0.3633 | 0.7221 | 0.2342 | 0.041* | |
H14C | 0.3191 | 0.8142 | 0.1448 | 0.041* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0556 (14) | 0.0307 (12) | 0.0565 (14) | 0.0088 (10) | 0.0440 (12) | 0.0049 (11) |
O2 | 0.0324 (11) | 0.0283 (11) | 0.0437 (12) | −0.0050 (9) | 0.0204 (10) | −0.0016 (9) |
N1 | 0.0164 (10) | 0.0252 (12) | 0.0200 (10) | 0.0002 (8) | 0.0077 (8) | 0.0009 (9) |
N2 | 0.0163 (10) | 0.0201 (10) | 0.0213 (10) | −0.0004 (8) | 0.0089 (8) | 0.0001 (8) |
C1 | 0.0195 (12) | 0.0268 (14) | 0.0220 (13) | −0.0010 (10) | 0.0060 (10) | −0.0026 (11) |
C2 | 0.0177 (12) | 0.0373 (16) | 0.0288 (14) | −0.0011 (11) | 0.0049 (11) | −0.0027 (12) |
C3 | 0.0150 (12) | 0.0370 (16) | 0.0348 (15) | −0.0011 (11) | 0.0125 (11) | −0.0017 (12) |
C4 | 0.0183 (12) | 0.0257 (14) | 0.0306 (14) | 0.0015 (10) | 0.0121 (11) | 0.0009 (11) |
C5 | 0.0234 (13) | 0.0441 (16) | 0.0309 (14) | 0.0015 (12) | 0.0192 (12) | 0.0031 (13) |
C6 | 0.0317 (14) | 0.0395 (16) | 0.0239 (13) | −0.0008 (12) | 0.0166 (12) | 0.0041 (12) |
C7 | 0.0248 (13) | 0.0202 (13) | 0.0224 (13) | −0.0009 (10) | 0.0103 (10) | 0.0014 (10) |
C8 | 0.0299 (14) | 0.0262 (14) | 0.0169 (12) | −0.0012 (11) | 0.0068 (11) | −0.0001 (10) |
C9 | 0.0199 (12) | 0.0245 (13) | 0.0247 (13) | 0.0003 (10) | 0.0032 (10) | 0.0008 (11) |
C10 | 0.0154 (12) | 0.0173 (12) | 0.0234 (13) | 0.0000 (9) | 0.0039 (10) | 0.0002 (10) |
C11 | 0.0187 (12) | 0.0163 (12) | 0.0219 (12) | 0.0003 (10) | 0.0085 (10) | −0.0005 (10) |
C12 | 0.0199 (12) | 0.0188 (12) | 0.0222 (12) | −0.0008 (10) | 0.0100 (10) | −0.0007 (10) |
C13 | 0.0242 (13) | 0.0524 (18) | 0.0207 (13) | −0.0001 (13) | 0.0064 (11) | −0.0009 (13) |
C14 | 0.0166 (12) | 0.0334 (15) | 0.0279 (14) | 0.0022 (11) | 0.0064 (11) | 0.0012 (12) |
O1—H1O | 0.84 (4) | C5—C6 | 1.345 (4) |
O1—H2O | 0.87 (5) | C6—H6 | 0.950 |
O2—H3O | 0.88 (4) | C6—C7 | 1.437 (3) |
O2—H4O | 0.89 (3) | C7—C8 | 1.404 (3) |
N1—C1 | 1.323 (3) | C7—C11 | 1.410 (3) |
N1—C12 | 1.350 (3) | C8—H8 | 0.950 |
N2—C10 | 1.329 (3) | C8—C9 | 1.365 (4) |
N2—C11 | 1.357 (3) | C9—H9 | 0.950 |
C1—C2 | 1.405 (4) | C9—C10 | 1.407 (3) |
C1—C13 | 1.509 (3) | C10—C14 | 1.497 (3) |
C2—H2 | 0.950 | C11—C12 | 1.457 (3) |
C2—C3 | 1.361 (4) | C13—H13A | 0.980 |
C3—H3 | 0.950 | C13—H13B | 0.980 |
C3—C4 | 1.414 (3) | C13—H13C | 0.980 |
C4—C5 | 1.431 (4) | C14—H14A | 0.980 |
C4—C12 | 1.412 (3) | C14—H14B | 0.980 |
C5—H5 | 0.950 | C14—H14C | 0.980 |
H1O—O1—H2O | 110 (3) | C7—C8—C9 | 119.3 (2) |
H3O—O2—H4O | 102 (3) | H8—C8—C9 | 120.4 |
C1—N1—C12 | 118.6 (2) | C8—C9—H9 | 120.0 |
C10—N2—C11 | 118.1 (2) | C8—C9—C10 | 120.1 (2) |
N1—C1—C2 | 122.5 (2) | H9—C9—C10 | 120.0 |
N1—C1—C13 | 116.4 (2) | N2—C10—C9 | 122.1 (2) |
C2—C1—C13 | 121.1 (2) | N2—C10—C14 | 116.5 (2) |
C1—C2—H2 | 120.2 | C9—C10—C14 | 121.4 (2) |
C1—C2—C3 | 119.6 (2) | N2—C11—C7 | 123.3 (2) |
H2—C2—C3 | 120.2 | N2—C11—C12 | 117.8 (2) |
C2—C3—H3 | 120.3 | C7—C11—C12 | 118.9 (2) |
C2—C3—C4 | 119.3 (2) | N1—C12—C4 | 122.7 (2) |
H3—C3—C4 | 120.3 | N1—C12—C11 | 118.3 (2) |
C3—C4—C5 | 122.9 (2) | C4—C12—C11 | 119.0 (2) |
C3—C4—C12 | 117.1 (2) | C1—C13—H13A | 109.5 |
C5—C4—C12 | 119.9 (2) | C1—C13—H13B | 109.5 |
C4—C5—H5 | 119.3 | C1—C13—H13C | 109.5 |
C4—C5—C6 | 121.3 (2) | H13A—C13—H13B | 109.5 |
H5—C5—C6 | 119.3 | H13A—C13—H13C | 109.5 |
C5—C6—H6 | 119.6 | H13B—C13—H13C | 109.5 |
C5—C6—C7 | 120.7 (2) | C10—C14—H14A | 109.5 |
H6—C6—C7 | 119.6 | C10—C14—H14B | 109.5 |
C6—C7—C8 | 122.7 (2) | C10—C14—H14C | 109.5 |
C6—C7—C11 | 120.1 (2) | H14A—C14—H14B | 109.5 |
C8—C7—C11 | 117.2 (2) | H14A—C14—H14C | 109.5 |
C7—C8—H8 | 120.4 | H14B—C14—H14C | 109.5 |
C12—N1—C1—C2 | 0.9 (4) | C8—C9—C10—C14 | −179.2 (2) |
C12—N1—C1—C13 | −179.6 (2) | C10—N2—C11—C7 | −2.0 (3) |
N1—C1—C2—C3 | 0.9 (4) | C10—N2—C11—C12 | 178.3 (2) |
C13—C1—C2—C3 | −178.6 (3) | C6—C7—C11—N2 | −178.1 (2) |
C1—C2—C3—C4 | −1.4 (4) | C6—C7—C11—C12 | 1.5 (3) |
C2—C3—C4—C5 | −179.9 (3) | C8—C7—C11—N2 | 1.9 (4) |
C2—C3—C4—C12 | 0.3 (4) | C8—C7—C11—C12 | −178.5 (2) |
C3—C4—C5—C6 | −179.8 (3) | C1—N1—C12—C4 | −2.1 (3) |
C12—C4—C5—C6 | −0.1 (4) | C1—N1—C12—C11 | 178.0 (2) |
C4—C5—C6—C7 | −0.8 (4) | C3—C4—C12—N1 | 1.5 (4) |
C5—C6—C7—C8 | −179.9 (3) | C3—C4—C12—C11 | −178.5 (2) |
C5—C6—C7—C11 | 0.1 (4) | C5—C4—C12—N1 | −178.2 (2) |
C6—C7—C8—C9 | 179.7 (2) | C5—C4—C12—C11 | 1.7 (4) |
C11—C7—C8—C9 | −0.3 (4) | N2—C11—C12—N1 | −2.8 (3) |
C7—C8—C9—C10 | −1.1 (4) | N2—C11—C12—C4 | 177.3 (2) |
C11—N2—C10—C9 | 0.6 (3) | C7—C11—C12—N1 | 177.6 (2) |
C11—N2—C10—C14 | −179.3 (2) | C7—C11—C12—C4 | −2.4 (3) |
C8—C9—C10—N2 | 1.0 (4) |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1O···N2 | 0.84 (4) | 2.31 (4) | 3.105 (3) | 157 (3) |
O1—H2O···O2 | 0.87 (5) | 1.95 (5) | 2.805 (3) | 167 (4) |
O2—H3O···N1i | 0.88 (4) | 2.15 (4) | 3.005 (3) | 164 (3) |
O2—H4O···O1ii | 0.89 (3) | 1.97 (3) | 2.810 (3) | 158 (3) |
Symmetry codes: (i) x, y−1, z; (ii) −x+1/2, −y+1/2, −z. |
Acknowledgements
The authors thank the EPSRC for equipment and partial studentship funding.
References
Allen, F. H. (2002). Acta Cryst. B58, 380–388. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Baggio, S., Baggio, R. & Mombrú, A. W. (1998). Acta Cryst. C54, 1900–1902. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555–1573. CrossRef CAS Web of Science Google Scholar
Brandenburg, K. & Putz, H. (2004). DIAMOND. Version 3. University of Bonn, Germany. Google Scholar
Britton, D., Thompson, L. C. & Holz, R. C. (1991). Acta Cryst. C47, 1101–1103. CSD CrossRef CAS Web of Science IUCr Journals Google Scholar
Bruker (2001). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Bulut, A., Uçar, I., Yeşilel, O. Z., Içbudak, H., Ölmez, H. & Büyükgüngör, O. (2004). Acta Cryst. C60, m526–m528. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Sheldrick, G. M. (2001). SHELXTL. Version 6. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Sheldrick, G. M. (2003). SADABS. University of Göttingen, Germany. Google Scholar
Uçar, I., Bulut, A. & Büyükgüngör, O. (2005). Acta Cryst. C61, m218–m220. Web of Science CSD CrossRef IUCr Journals Google Scholar
Uçar, I., Yeşilel, O. Z., Bulut, A., Ölmez, H. & Büyükgüngör, O. (2004). Acta Cryst. E60, m1025–m1027. Web of Science CSD CrossRef IUCr Journals Google Scholar
© International Union of Crystallography. Prior permission is not required to reproduce short quotations, tables and figures from this article, provided the original authors and source are cited. For more information, click here.