[5 Amino 6,8 di­chloro 2,3 bis­(2 pyridyl)­quinoxaline]­di­chloro­zinc(II)

(1)metal-organic papers [5-Amino-6,8-dichloro-2,3-bis(2-pyridyl)quinoxaline]dichlorozinc(II). Acta Crystallographica Section E. Structure Reports Online ISSN 1600-5368. Dao-Li An,a Miao Du,a Xian-He Bu,a* Kumar Biradhab and Mitsuhiko Shionoyac a Department of Chemistry, Nankai University, Tianjin 300071, People's Republic of China, b Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan, and cDepartment of Chemistry, Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan. The ZnII atom in the title complex, [ZnCl2(C18H11N5Cl2)], has a distorted tetrahedral environment formed by the N atoms of two quinoxaline ortho-pyridyl substituents and two terminal chloro ligands. There is a symmetry-independent intermolecular hydrogen bond in the crystal, which links one of the H atoms of the aniline group with one of the chloro ligands Ê and Cl  HÐN 142 ]. This hydrogen bond [Cl  N 3.418 (3) A is responsible for the formation of in®nite zigzag chains, which run along the b axis of the crystal.. Received 17 June 2002 Accepted 8 July 2002 Online 19 July 2002. Correspondence e-mail: buxh@nankai.edu.cn. Comment Key indicators Single-crystal X-ray study T = 193 K Ê Mean (C±C) = 0.007 A R factor = 0.046 wR factor = 0.088 Data-to-parameter ratio = 13.6 For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e.. # 2002 International Union of Crystallography Printed in Great Britain ± all rights reserved. m436. Dao-Li An et al.. . Polypyridyl ligands and their transition metal complexes have attracted much interest owing to their potential as building blocks for supramolecular assemblies, as well as their possible use in optical sensors and probes for nucleic acids (Arkin et al., 1996; Holmlin et al., 1999). 2,3-Bis(2-pyridyl)quinoxaline and its derivatives represent an important class of chelating agents which have been extensively studied over the last two decades (Balzani et al., 1996; Scott et al., 1999). However, most of the results were obtained for RuII, OsII, and ReI complexes, whereas studies on ®rst row transition metals are still quite rare. We report herein the synthesis and crystal structure of the zinc(II) complex [5-amino-6,8-dichloro-2,3-bis(2-pyridyl)quinoxaline]dichlorozinc(II), (I) (Fig. 1).. The ZnII atom has a distorted tetrahedral coordination, formed by the N atoms of two ortho-pyridyl groups of the chelate system and two chloro ligands. The ortho-pyridyl substituents in the quinoxaline system can not be coplanar, either with each other or with the quinoxaline moiety, as a planar conformation would cause sterically unacceptable contacts between the pyridyl rings. In fact, the existence of the adjacent pyridyl substituents causes substantial out-of-plane twist, even within the quinoxaline itself, the torsion angle C1AÐC2ÐC3ÐC1B being ÿ4.1 (1) ; the mean atomic displacement from the least-squares quinoxaline plane is Ê . The two pyridine rings form dihedral angles of 0.0345 (2) A. [ZnCl2(C18H11N5Cl2)]. DOI: 10.1107/S1600536802011996. Acta Cryst. (2002). E58, m436±m438.

(2) metal-organic papers chloro-2,3-bis(2-pyridyl)quinoxaline (147 mg, 0.4 mmol) in CHCl3 (20 ml) was left to stand at room temperature. Yellow crystals precipitated slowly with the evaporation of the solvent. Yield: 75%. FT±IR data (KBr pellet, cmÿ1): 3490 (m), 3380 (s), 1602 (vs), 1570 (m), 1487 (s), 1458 (m), 1349 (vs), 1029 (s), 789 (m), 755 (m). Analysis calculated for the title complex: C 42.85, H 2.20, N 13.89%; found: C 42.81, H 2.40, N 13.83%. Crystal data. Figure 1. ORTEPII view (Johnson, 1976) of the title complex, shown with 30% probability displacement ellipsoids.. 115.1 (3) and 53.3 (2) with the mean quinoxaline plane, and a dihedral angle of 94.4 (3) with each other. Selected bond distances and angles are given in Table 1. The C2ÐN1 and C3ÐN2 bond distances [1.318 (6) and Ê , respectively] are noticeably shorter than N1ÐC9 1.315 (6) A Ê , respectively], which is and N2ÐC4 [1.354 (6) and 1.351 (6) A typical for quinoxaline system geometry (Rasmussen et al., 1990). All NÐC bond lengths are well within the range between the ranges normally considered standard for single Ê (Sasada, 1984) and CÐN and double C N bonds [1.47 A Ê (Wang et al., 1998), respectively]. 1.28 A Although there are two `active' H atoms in the structure, only one of them (H3C) actually takes part in intermolecular hydrogen bonding. The hydrogen bond N3ÐH3C  Cl4i Ê and N3ÐH3C  Cl3i 142 ; symmetry [N3  Cl3i 3.418 (3) A code: (i) ÿx, yÿ1/2, 1/2ÿz] links the molecules of the complex into in®nite chains along the b axis of the crystal (Fig. 2).. Experimental The title complex was synthesized by the reaction of 1-nitro-2,3phenylenediamine and 2,20 -bipyridyl, and then reduced by Pd/C in the presence of concentrated (36%) HCl under re¯ux. The details will be published elsewhere. A mixture of solutions of equimolecular ZnCl2 (55 mg, 0.4 mmol) in CH3OH (30 ml) and 5-amino-6,8-di-. Dx = 1.710 Mg mÿ3 Mo K radiation Cell parameters from 10665 re¯ections  = 1.3±25.0  = 1.81 mmÿ1 T = 193 (2) K Prism, yellow 0.30  0.25  0.20 mm. [ZnCl2(C18H11N5Cl2)] Mr = 504.49 Monoclinic, P21 =c Ê a = 16.097 (9) A Ê b = 8.922 (3) A Ê c = 13.858 (4) A

(3) = 100.04 (3) Ê3 V = 1959.8 (14) A Z=4. Data collection 3451 independent re¯ections 2107 re¯ections with I > 2(I) Rint = 0.096 max = 25.0 h = ÿ19 ! 10 k = ÿ9 ! 10 l = ÿ13 ! 16. Bruker SMART 1000 diffractometer ! scans Absorption correction: multi-scan [SAINT (Bruker, 1998) and SADABS (Sheldrick, 1997)] Tmin = 0.612, Tmax = 0.713 10833 measured re¯ections. Re®nement Re®nement on F 2 R[F 2 > 2(F 2)] = 0.046 wR(F 2) = 0.088 S = 1.04 3451 re¯ections 254 parameters. H-atom parameters constrained w = 1/[ 2(Fo2) + (0.0256P)2] where P = (Fo2 + 2Fc2)/3 (/)max = 0.006 Ê ÿ3 max = 0.47 e A Ê ÿ3 min = ÿ0.45 e A. Table 1. Ê ,  ). Selected geometric parameters (A ZnÐN1A ZnÐN1B ZnÐCl3 ZnÐCl4 N1ÐC2. 2.062 (4) 2.056 (4) 2.2218 (18) 2.2093 (17) 1.318 (6). N1ÐC9 N2ÐC3 N2ÐC4 N3ÐC5. 1.354 (6) 1.315 (6) 1.351 (6) 1.371 (6). N1BÐZnÐN1A N1BÐZnÐCl4 N1AÐZnÐCl4. 91.32 (15) 113.73 (13) 112.42 (12). N1BÐZnÐCl3 N1AÐZnÐCl3 Cl4ÐZnÐCl3. 107.47 (12) 106.32 (13) 121.30 (6). Table 2. Ê ,  ). Hydrogen-bonding geometry (A DÐH  A N3ÐH3C  Cl4. i. DÐH. H  A. D  A. DÐH  A. 0.88. 2.68. 3.418 (3). 142. Symmetry code: (i) ÿx; y ÿ 12; 12 ÿ z.. Figure 2. View of the zigzag chain in the crystal of the title complex. Acta Cryst. (2002). E58, m436±m438. All H atoms were placed in geometrically calculated positions and included in the ®nal re®nement in the riding-model approximation, with displacement parameters derived from the atoms to which they were bonded. The Uiso values for the H atoms were set at 1.2Ueq of the parent atom values. Data collection: SMART (Bruker, 1998); cell re®nement: SMART; data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to re®ne Dao-Li An et al.. . [ZnCl2(C18H11N5Cl2)]. m437.

(4) metal-organic papers structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: SHELXTL (Bruker, 1998).. The authors gratefully acknowledge ®nancial support from the National Natural Science Foundation of China (No. 29971019).. References Arkin, M. R., Stemp, E. D. A., Holmlin, R. E., Barton, J. K., Hormann, A., Olson, E. J. C. & Barbara, P. F. (1996). Science, 273, 475±480. Balzani, V., Juris, A., Venturi, M., Campagna, S. & Serroni, S. (1996). Chem. Rev. 96, 759±833.. m438. Dao-Li An et al.. . [ZnCl2(C18H11N5Cl2)]. Bruker (1998). SMART, SAINT and SHELXTL. Bruker AXS Inc., Madison, Wisconsin, USA. Holmlin, R. E., Yao, J. A. & Barton, J. K. (1999). Inorg. Chem. 38, 174± 189. Johnson, C. K. (1976). ORTEPII. Report ORNL-5138. Oak Ridge National Laboratory, Tennessee, USA. Rasmussen, S. C., Richter, M. M., Yi, E., Place, H. & Brewer, K. J. (1990). Inorg. Chem. 29, 3926±3932. Sasada, Y. (1984). Molecular and Crystal Structures, in Chemistry Handbook, 3rd ed. Tokyo: The Chemical Society of Japan. Scott, S. M., Gordon, K. C. & Burrell, A. K. (1999). J. Chem. Soc. Dalton Trans. pp. 2669±2673. Sheldrick, G. M. (1997). SADABS, SHELXS97 and SHELXL97. University of GoÈttingen, Germany. Wang, Z.-X., Jian, F.-F., Duan, C.-Y., Bai, Z.-P. & You, X.-Z. (1998). Acta Cryst. C54, 1927±1929.. Acta Cryst. (2002). E58, m436±m438.

(5) supporting information. supporting information Acta Cryst. (2002). E58, m436–m438. [https://doi.org/10.1107/S1600536802011996]. [5-Amino-6,8-dichloro-2,3-bis(2-pyridyl)quinoxaline]dichlorozinc(II) Dao-Li An, Miao Du, Xian-He Bu, Kumar Biradha and Mitsuhiko Shionoya [5-Amino-6,8-dichloro-2,3-bis(2-pyridyl)quinoxaline]dichlorozinc(II) Crystal data [ZnCl2(C18H11N5Cl2)] Mr = 504.49 Monoclinic, P21/c a = 16.097 (9) Å b = 8.922 (3) Å c = 13.858 (4) Å β = 100.04 (3)° V = 1959.8 (14) Å3 Z=4. F(000) = 1008 Dx = 1.710 Mg m−3 Mo Kα radiation, λ = 0.71073 Å Cell parameters from 10665 reflections θ = 1.3–25.0° µ = 1.81 mm−1 T = 193 K Prism, yellow 0.30 × 0.25 × 0.20 mm. Data collection Bruker SMART 1000 diffractometer ω scans Absorption correction: multi-scan [SAINT (Bruker 1998) and SADABS (Sheldrick, 1997)] Tmin = 0.612, Tmax = 0.713 10833 measured reflections. 3451 independent reflections 2107 reflections with I > 2σ(I) Rint = 0.096 θmax = 25.0° h = −19→10 k = −9→10 l = −13→16. Refinement Refinement on F2 R[F2 > 2σ(F2)] = 0.046 wR(F2) = 0.088 S = 1.04 3451 reflections 254 parameters. H-atom parameters constrained w = 1/[σ2(Fo2) + (0.0256P)2] where P = (Fo2 + 2Fc2)/3 (Δ/σ)max = 0.006 Δρmax = 0.47 e Å−3 Δρmin = −0.45 e Å−3. Special details 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. Full-MATRIX. Acta Cryst. (2002). E58, m436–m438. sup-1.

(6) supporting information Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2). Zn Cl1 Cl2 Cl3 Cl4 N1 N2 N3 H3C H3D C2 C3 C4 C5 C6 C7 H7 C8 C9 N1A C1A C2A H2A C3A H3A C4A H4A C5A H5A N1B C1B C2B H2B C3B H3B C4B H4B C5B H5B. x. y. z. Uiso*/Ueq. 0.33071 (4) −0.18991 (10) 0.06455 (10) 0.44506 (9) 0.21520 (9) 0.1754 (3) 0.1164 (3) −0.0538 (3) −0.1080 −0.0167 0.2280 (3) 0.1975 (3) 0.0613 (3) −0.0271 (3) −0.0823 (3) −0.0537 (4) −0.0936 0.0307 (4) 0.0916 (3) 0.3706 (3) 0.3189 (3) 0.3480 (4) 0.3112 0.4306 (4) 0.4516 0.4826 (4) 0.5393 0.4506 (4) 0.4872 0.3092 (3) 0.2522 (3) 0.2420 (3) 0.2026 0.2895 (4) 0.2825 0.3469 (3) 0.3802 0.3551 (3) 0.3947. 0.47111 (6) 0.55278 (17) 0.95320 (16) 0.42847 (14) 0.56715 (14) 0.6791 (4) 0.3866 (4) 0.3202 (4) 0.2995 0.2472 0.5662 (5) 0.4169 (5) 0.5008 (5) 0.4662 (6) 0.5861 (6) 0.7365 (6) 0.8157 0.7689 (6) 0.6503 (5) 0.5888 (4) 0.6064 (5) 0.6681 (5) 0.6784 0.7137 (5) 0.7552 0.6991 (5) 0.7329 0.6344 (5) 0.6215 0.2828 (4) 0.2817 (5) 0.1585 (5) 0.1605 0.0313 (5) −0.0551 0.0306 (5) −0.0556 0.1577 (5) 0.1574. 0.25157 (4) 0.34475 (11) 0.39969 (11) 0.18617 (10) 0.16385 (9) 0.4168 (3) 0.3805 (3) 0.3560 (3) 0.3466 0.3589 0.4158 (3) 0.3938 (3) 0.3809 (3) 0.3661 (3) 0.3623 (3) 0.3730 (3) 0.3686 0.3895 (4) 0.3950 (3) 0.3793 (3) 0.4452 (3) 0.5377 (4) 0.5840 0.5606 (4) 0.6233 0.4925 (4) 0.5063 0.4038 (4) 0.3576 0.3291 (3) 0.3910 (3) 0.4469 (3) 0.4905 0.4393 (4) 0.4772 0.3766 (4) 0.3706 0.3229 (3) 0.2795. 0.02659 (17) 0.0520 (4) 0.0530 (4) 0.0412 (4) 0.0370 (4) 0.0258 (10) 0.0254 (10) 0.0368 (12) 0.044* 0.044* 0.0233 (12) 0.0212 (11) 0.0269 (12) 0.0290 (12) 0.0332 (13) 0.0384 (15) 0.046* 0.0344 (14) 0.0247 (12) 0.0254 (10) 0.0239 (12) 0.0315 (14) 0.038* 0.0356 (15) 0.043* 0.0353 (15) 0.042* 0.0321 (13) 0.039* 0.0238 (10) 0.0242 (12) 0.0306 (13) 0.037* 0.0386 (14) 0.046* 0.0335 (13) 0.040* 0.0269 (12) 0.032*. Atomic displacement parameters (Å2). Zn Cl1. U11. U22. U33. U12. U13. U23. 0.0280 (4) 0.0281 (9). 0.0221 (3) 0.0651 (10). 0.0305 (3) 0.0610 (9). 0.0013 (3) 0.0023 (8). 0.0073 (3) 0.0029 (8). 0.0025 (3) 0.0095 (8). Acta Cryst. (2002). E58, m436–m438. sup-2.

(7) supporting information Cl2 Cl3 Cl4 N1 N2 N3 C2 C3 C4 C5 C6 C7 C8 C9 N1A C1A C2A C3A C4A C5A N1B C1B C2B C3B C4B C5B. 0.0506 (11) 0.0381 (10) 0.0353 (9) 0.029 (3) 0.029 (3) 0.023 (3) 0.030 (3) 0.021 (3) 0.030 (3) 0.025 (3) 0.029 (4) 0.036 (4) 0.034 (4) 0.029 (4) 0.024 (3) 0.028 (4) 0.042 (4) 0.036 (4) 0.033 (4) 0.031 (4) 0.024 (3) 0.022 (3) 0.030 (4) 0.049 (4) 0.033 (4) 0.020 (3). 0.0349 (8) 0.0358 (8) 0.0390 (8) 0.026 (2) 0.026 (2) 0.034 (3) 0.020 (3) 0.025 (3) 0.030 (3) 0.037 (3) 0.047 (3) 0.049 (4) 0.034 (3) 0.031 (3) 0.018 (2) 0.009 (2) 0.019 (3) 0.024 (3) 0.025 (3) 0.022 (3) 0.021 (2) 0.022 (3) 0.028 (3) 0.020 (3) 0.020 (2) 0.025 (3). 0.0716 (10) 0.0551 (9) 0.0357 (8) 0.023 (2) 0.023 (2) 0.053 (3) 0.021 (3) 0.019 (3) 0.021 (3) 0.024 (3) 0.024 (3) 0.032 (3) 0.035 (3) 0.015 (3) 0.034 (2) 0.033 (3) 0.034 (3) 0.040 (3) 0.045 (4) 0.044 (3) 0.026 (2) 0.028 (3) 0.036 (3) 0.048 (3) 0.048 (3) 0.036 (3). 0.0093 (8) 0.0064 (7) 0.0099 (7) 0.001 (2) −0.003 (2) −0.002 (2) −0.001 (2) −0.001 (2) 0.001 (3) 0.002 (3) 0.004 (3) 0.017 (3) 0.007 (3) 0.006 (3) 0.001 (2) 0.001 (2) 0.001 (3) −0.006 (3) −0.002 (3) −0.002 (3) 0.000 (2) 0.000 (2) 0.000 (3) 0.001 (3) 0.005 (3) −0.001 (2). 0.0055 (8) 0.0232 (8) 0.0031 (7) 0.006 (2) 0.008 (2) 0.006 (2) 0.006 (2) 0.005 (2) 0.006 (2) 0.005 (2) 0.006 (3) 0.010 (3) 0.006 (3) 0.007 (3) 0.005 (2) 0.001 (3) 0.007 (3) −0.011 (3) 0.000 (3) 0.007 (3) 0.004 (2) 0.003 (3) 0.010 (3) 0.013 (3) 0.009 (3) 0.004 (3). −0.0061 (7) 0.0039 (6) 0.0063 (6) −0.0032 (17) 0.0007 (17) 0.005 (2) −0.002 (2) 0.005 (2) 0.004 (2) 0.003 (2) 0.008 (2) 0.005 (3) −0.001 (2) 0.000 (2) 0.0027 (17) 0.003 (2) −0.002 (2) −0.007 (2) 0.001 (2) 0.005 (2) −0.0011 (17) −0.002 (2) 0.008 (2) 0.009 (3) 0.000 (2) −0.004 (2). Geometric parameters (Å, º) Zn—N1A Zn—N1B Zn—Cl3 Zn—Cl4 Cl2—C8 Cl1—C6 N1—C2 N1—C9 N2—C3 N2—C4 N3—C5 N3—H3C N3—H3D C2—C3 C2—C1A C3—C1B C4—C9 C4—C5 C9—C8. Acta Cryst. (2002). E58, m436–m438. 2.062 (4) 2.056 (4) 2.2218 (18) 2.2093 (17) 1.730 (5) 1.732 (6) 1.318 (6) 1.354 (6) 1.315 (6) 1.351 (6) 1.371 (6) 0.8800 0.8800 1.434 (6) 1.492 (7) 1.498 (6) 1.423 (6) 1.435 (7) 1.436 (7). C6—C5 N1A—C5A N1A—C1A C1A—C2A C2A—C3A C2A—H2A C3A—C4A C3A—H3A C4A—C5A C4A—H4A C5A—H5A N1B—C5B N1B—C1B C1B—C2B C2B—C3B C2B—H2B C3B—C4B C3B—H3B C4B—C5B. 1.386 (7) 1.337 (6) 1.348 (6) 1.399 (6) 1.373 (7) 0.9500 1.373 (7) 0.9500 1.373 (7) 0.9500 0.9500 1.349 (6) 1.360 (6) 1.371 (6) 1.383 (7) 0.9500 1.374 (7) 0.9500 1.375 (6). sup-3.

(8) supporting information C8—C7 C7—C6 C7—H7. 1.369 (7) 1.417 (7) 0.9500. C4B—H4B C5B—H5B. 0.9500 0.9500. N1B—Zn—N1A N1B—Zn—Cl4 N1A—Zn—Cl4 N1B—Zn—Cl3 N1A—Zn—Cl3 Cl4—Zn—Cl3 C2—N1—C9 C3—N2—C4 C5—N3—H3C C5—N3—H3D H3C—N3—H3D N1—C2—C3 N1—C2—C1A C3—C2—C1A N2—C3—C2 N2—C3—C1B C2—C3—C1B N2—C4—C9 N2—C4—C5 C9—C4—C5 N1—C9—C4 N1—C9—C8 C4—C9—C8 C7—C8—C9 C7—C8—Cl2 C9—C8—Cl2 C8—C7—C6 C8—C7—H7 C6—C7—H7 C5—C6—C7 C5—C6—Cl1 C7—C6—Cl1 N3—C5—C6 N3—C5—C4 C6—C5—C4 C5A—N1A—C1A. 91.32 (15) 113.73 (13) 112.42 (12) 107.47 (12) 106.32 (13) 121.30 (6) 118.0 (4) 118.8 (4) 120.0 120.0 120.0 121.1 (5) 114.5 (4) 124.4 (4) 121.0 (4) 113.9 (4) 124.9 (5) 119.9 (5) 118.2 (4) 121.9 (5) 120.9 (4) 121.1 (5) 118.0 (5) 120.1 (5) 120.3 (4) 119.6 (4) 120.8 (5) 119.6 119.6 122.1 (5) 119.5 (4) 118.4 (4) 122.8 (5) 120.3 (5) 116.9 (5) 118.3 (4). C5A—N1A—Zn C1A—N1A—Zn N1A—C1A—C2A N1A—C1A—C2 C2A—C1A—C2 C3A—C2A—C1A C3A—C2A—H2A C1A—C2A—H2A C4A—C3A—C2A C4A—C3A—H3A C2A—C3A—H3A C3A—C4A—C5A C3A—C4A—H4A C5A—C4A—H4A N1A—C5A—C4A N1A—C5A—H5A C4A—C5A—H5A C5B—N1B—C1B C5B—N1B—Zn C1B—N1B—Zn N1B—C1B—C2B N1B—C1B—C3 C2B—C1B—C3 C1B—C2B—C3B C1B—C2B—H2B C3B—C2B—H2B C4B—C3B—C2B C4B—C3B—H3B C2B—C3B—H3B C3B—C4B—C5B C3B—C4B—H4B C5B—C4B—H4B N1B—C5B—C4B N1B—C5B—H5B C4B—C5B—H5B. 121.0 (3) 120.2 (3) 121.2 (5) 118.7 (4) 120.0 (5) 119.0 (5) 120.5 120.5 119.6 (5) 120.2 120.2 118.5 (6) 120.7 120.7 123.3 (5) 118.4 118.4 118.1 (4) 119.9 (3) 121.9 (3) 121.5 (4) 118.3 (4) 120.1 (5) 119.5 (5) 120.3 120.3 119.6 (5) 120.2 120.2 118.5 (5) 120.7 120.7 122.8 (5) 118.6 118.6. Hydrogen-bond geometry (Å, º) D—H···A N3—H3C···Cl4. i. D—H. H···A. D···A. D—H···A. 0.88. 2.68. 3.418 (3). 142. Symmetry code: (i) −x, y−1/2, −z+1/2.. Acta Cryst. (2002). E58, m436–m438. sup-4.

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