C18H12Br2CuN4O2, monoclinic, P21/c (no. 14), a = 11.5165(11) Å, b = 5.4369(5) Å, c = 14.4872(14) Å, V = 873.52(14) Å3, Z = 2, R gt (F) = 0.0232, wR ref (F2) = 0.0559, T = 200 K.
|Size:||0.25 × 0.10 × 0.08 mm|
|Wavelength:||Mo Kα radiation (0.71073 Å)|
|Diffractometer, scan mode:||Bruker Apex-II, φ and ω|
|θmax, completeness:||30.6°, >99%|
|N(hkl)measured, N(hkl)unique, Rint:||24890, 2680, 0.031|
|Criterion for Iobs, N(hkl)gt:||Iobs > 2 σ(Iobs), 2239|
|Programs:||Bruker , SHELX , Mercury , PLATON , WinGX/ORTEP , |
|Br1||0.92682 (2)||0.29323 (4)||0.29381 (2)||0.03565 (7)|
|C1||0.71540 (16)||0.8184 (3)||0.45057 (13)||0.0247 (3)|
|C2||0.83933 (18)||0.8481 (4)||0.45822 (16)||0.0351 (4)|
|C3||0.90086 (18)||0.6939 (4)||0.41266 (17)||0.0364 (5)|
|C4||0.84106 (17)||0.5011 (3)||0.35819 (13)||0.0271 (4)|
|C5||0.72055 (16)||0.4605 (3)||0.34963 (12)||0.0247 (3)|
|C6||0.65605 (15)||0.6163 (3)||0.39524 (11)||0.0213 (3)|
|C7||0.52762 (15)||0.5696 (3)||0.38121 (11)||0.0211 (3)|
|C8||0.45589 (16)||0.3758 (3)||0.33160 (12)||0.0260 (4)|
|C9||0.34164 (16)||0.4199 (4)||0.33940 (13)||0.0270 (4)|
|H1||0.295 (2)||0.704 (5)||0.4089 (17)||0.037 (7)*|
|N1||0.45866 (13)||0.7188 (3)||0.41696 (10)||0.0227 (3)|
|N2||0.34578 (14)||0.6249 (3)||0.39083 (11)||0.0258 (3)|
|O1||0.66406 (11)||0.9777 (2)||0.49569 (10)||0.0290 (3)|
Source of material
A warm DMF (3 cm3) Cu(NO3)2⋅3H2O solution (0.5 mmol) was slowly heated with a warm DMF (3 cm3) 4–bromo-2- (1H-pyrazol-3-yl) phenol (0.25 mmol) ligand solution. The resulting green-brown solution was allowed to crystallize by slow evaporation at room temperature. After two days, the dark green single crystals of the complex were filtered and washed with a small amount of DMF. Yield: 0.01 g. FTIR–ATR (Bruker Tensor 27 FTIR–ATR spectrometer) ν (cm−1): 3330, 3145, 1487, 1431, 1402, 1369, 972.
All hydrogen atoms were located from a difference Fourier map. The nitrogen-bound H atom was refined freely, along with its isotropic displacement parameter. The remaining H atoms were constrained to ride on their parent atoms with Uiso(H) = 1.2Ueq(C).
Pyrazolyl molecules exhibit various biologically relevant properties including anti-inflammatory, analgesic and anti-cancer effects , . Due to their various coordination capabilities, pyrazole derivatives are used for the extraction of metal ions  and also for the formation of metal organic frameworks . Usage of pyrazole derivatives in processes involving metal atoms is related to their versatile coordinating properties. Rigidity of the pyrazole ring diminishes potential variation of the steric properties of the pyrazole derivatives, which makes these molecules a convenient choice in attempts to control the influence of the various substituents on the complexation properties as well as intra and inter molecular interactions. As part of our ongoing research on the synthesis, physico-chemical and structural properties of pyrazole based coordination compounds ,  herein we report the crystal structure of the title compound. We reported previously the crystal structure of uncoordinated 4-bromo-2-(1H-pyrazol-3-yl) phenol . Addition of halogenated phenols to the pyrazolyl ring adds new possibilities for both coordination, and intermolecular interactions. Geometrical constraints make the deprotonated phenolic oxygen the likely site for bonding to metal, while the halogen substituent can potentially form hydrogen bond or halogen-halogen interaction . The structure is built up of isolated units with a copper(II) ion located on an inversion center. Two molecules of the [4-bromo-2-(1H-pyrazol-3-yl) phenolato ligand are coordinated through the phenolate-O and pyridine-like nitrogen of the pyrazole moiety arranged in a square-planar geometry resulting in a trans disposition of these ligands (left part of the Figure). To gain better insight into the coordinating properties of this ligand we performed a CSD search  (CSD version 5.41) using the chemical structure of the title ligand, with exclusion of hydrogen atoms, and Br substituted by any halogen atom, as a template. This search returned only seven hits, having the CSD refcodes AHIZIB, AHIZIB01, CIVVEJ, CIVVIN, CIVVOT, TEQHEE and TEQHII (the last two structures contain Cl instead of Br). As opposed to the mononuclear complex found in the title structure, all seven structures consist of trinuclear complexes. This is associated with different coordinating capabilities of the pyrazolyl ligand achieved through additional deprotonation at pyrrolic–N thus making it a tridentate ligand. The title complex possesses capabilities for hydrogen bonding involving Br , however, association of molecules is achieved through chelate-chelate stacking  and Br⋯Br interactions . Figure, on the right, depicts associations of molecules into the chains through the stacking interactions between the six-membered chelate ring and pyrazole ring at a distance of 3.2848(10) Å. Neighboring chains are connected by Br⋯Br interactions (Br1⋯Br1 = 3.6050(5) Å, C4–Br1⋯Br1 = 95°, Br1⋯Br1–C4 = 167°. The geometry of the C–Br⋯Br–C contacts indicates that it is a type II halogen⋯halogen contact  which represents an attractive interaction .
Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.
Research funding: None declared.
Conflict of interest statement: The authors declare no conflicts of interest regarding this article.
1. Bruker. APEX2, SAINT and SADABS; Bruker AXS Inc: Madison, Wisconsin, USA, 2009. Search in Google Scholar
3. Macrae, C. F., Edgington, P. R., McCabe, P., Pidcock, E., Shields, G. P., Taylor, R., van der Streek, T. Mercury 4.0: from visualization to analysis, design and prediction. J. Appl. Crystallogr. 2020, 39, 453–457; https://doi.org/10.1107/S1600576719014092. Search in Google Scholar
7. Khan, M. F., Alam, M. M., Verma, G., Akhtar, W., Akhter, M., Shaquiquzzaman, M. The therapeutic voyage of pyrazole and its analogs: a review. Eur. J. Med. Chem. 2016, 120, 170–201; https://doi.org/10.1016/j.ejmech.2016.04.077. Search in Google Scholar
8. Alam, J., Alam, O., Alam, P., Naim, M. J. A review on pyrazole chemical entity and biological activity. Int. J. Pharm. Sci. Res. 2015, 6, 1433–1442. Search in Google Scholar
9. Attayibat, A., Radi, S., Lekchiri, Y., Ramdani, A., Hacht, B., Bacquet, M., Willai, S., Morcellet, M. New functionalised C,C bipyrazoles. synthesis and cation binding properties. J. Chem. Res. 2006, 10, 655–657; https://doi.org/10.3184/030823406779173587. Search in Google Scholar
10. Pettinari, C., Tabacaru, A., Galli, S. Coordination polymers and metal-organic frameworks based on poly(pyrazole)-containing ligands. Coord. Chem. Rev. 2016, 307, 1–31; https://doi.org/10.1016/j.ccr.2015.08.005. Search in Google Scholar
11. Jaćimović, Ž. K., Leovac, V. M., Tomić, Z. D. Crystal structure of hexakis(μ2-chloro)-κ4-oxo- tetrakis((3,5-dimethylpyrazole)copper(II)) ethanol tetrasolvate, Cu4OCl6(C5H8N2)4⋅4C2H5OH. Z. Kristallogr. NCS 2007, 222, 246–248. Search in Google Scholar
12. Jaćimović, Ž. K., Giester, G., Kosović, M., Bogdanović, G. A., Novaković, S. B., Leovac, V. M., Latinović, N., Holló, B. B., Meszaros Szecsenyi, K. Pyrazole-type complexes with Ni(II) and Cu(II). solvent exchange reactions in coordination compounds. J. Therm. Anal. Calorim. 2017, 127, 1501–1509. Search in Google Scholar
13. Jaćimović, Ž. K., Kosović, M., Novaković, S. B., Bogdanović, G. A., Giester, G., Kastratović, V. Crystal structure of 4-bromo-2-(1H-pyrazol-3-yl) phenol, C9H7BrN2O. Z. Kristallogr. NCS 2017, 232, 507–509. Search in Google Scholar
14. Lieberman, H. F., Davey, R. J., Newsham, D. M. T. Br⋯Br and Br⋯H interactions in action: polymorphism, hopping, and twinning in 1,2,4,5-tetrabromobenzene. Chem. Mater. 2000, 12, 490–494; https://doi.org/10.1021/cm991123p. Search in Google Scholar
16. Sredojević, D. N., Tomić, Z. D., Zarić, S. D. Evidence of chelate-chelate stacking interactions in crystal structures of transition-metal complexes. Cryst. Growth Des. 2010, 10, 3901–3908; https://doi.org/10.1021/cg100312r. Search in Google Scholar
17. Pedireddi, V. R., Reddy, D. S., Goud, S., Craig, D. C., Raeb, A. B., Desiraju, G. R. The nature of halogen. halogen interactions and the crystal structure of 1,3,5,7-tetraiodoadamantane. J. Chem. Soc., Perkin Trans. 1994, 2, 2353–2360; https://doi.org/10.1039/p29940002353. Search in Google Scholar
© 2021 Željko K. Jaćimović et al., published by De Gruyter, Berlin/Boston
This work is licensed under the Creative Commons Attribution 4.0 International License.