Powder diffraction and synchrotron radiation, a powerful tool in the investigation of new compounds: CdBr 2 (3-fluoroaniline) 2 and CdBr 2 (4-fluoroaniline) 2 M. Grzesiak-Nowak, a * G. Appleby b and W. Lasocha a,c Using synchrotron powder diffraction data, two new complexes of CdBr 2 with 3-fluoroaniline and 4-fluoroaniline were fully characterised with regard to their structure. Their crystal structures were solved and refined by means of powder diffraction tech- niques. The investigated materials belong to the group of hybrid inorganic–organic coordination polymers. The structures of both compounds are created by the same type, infinite chains formed by CdBr 4 N 2 octahedra. Each cadmium cation is surrounded by four Br À anions, and two N atoms from two fluoroaniline molecules. The obtained structural data enable us to investigate the influence of the position of the F atom in the aniline ring on the crystal structure, as well as to interpret its thermal stability. Copyright © 2015 John Wiley & Sons, Ltd. Introduction It is known that transition metal halides Me(tr)X 2 (Me(tr) and X denote any transition metal and halogen atom) easily react with amines forming compounds with interesting architectures. [1,2] Among amines, fluorine-substituted aniline is particularly interest- ing, because beside coordination bonds with Me(tr), π–π interac- tions and hydrogen bonds can be formed. It is a common belief that C–H…F–C hydrogen bonding does not play an important role in molecular interaction when other stronger interactions (π–π stacking) are present. [3] Moreover, hydrogen bonds with fluorine as acceptor are rare, but it has been reported that this kind of molecular interactions can be strong enough to pair two independent molecules. [4] In the beginning of our investigations, we have searched Cambridge Structural Database (CSD) for compounds containing Me(tr)X 2 and fluoroaniline. We were surprised that only 11 such entries can be found. Among them, there are eight compounds with Pd as central atom; in ten compounds, chlorine was used as the ligand X. Pd atoms exhibit strong tendency to be present in square planar coordination (coordination number is 4). [3] Other elements used as central atoms in such compounds are Ni, [5] Zn [6] and Ru. [7] Unfortunately, these compounds do not exhibit interest- ing structure features and form isolated single molecules. We have concluded that the usage of bigger central atom such as Cd and bromine as ligand X could result in connection of isolated struc- tural motifs. To the investigations, we selected CdBr 2 complexes with 2-fluoroaniline, 3-fluoroaniline and 4-fluoroaniline trying to elucidate influence of F atom position on the obtained crystal structure. Our aim was therefore to test the possibility of obtaining new interesting structural motifs using bigger components of inorganic centres Me(tr)X 2 . The second task was the verification of the possibility of C–F…H bond formation and qualification of their importance for the structure and compound properties. In this study, we present two hybrid organic–inorganic cadmium compounds with two fluoroanilines. In our compounds, C–H…F–C interactions are present and seem to play an important role in the formation of two-dimensional and three-dimensional extended structures. In the case of our materials, we cannot obtain single crystals. Their powder diffraction patterns have been looking very promis- ing; we could index them without any doubt. However, they were not good enough to enable us to solve their crystal struc- tures. The reason may be that the patterns were affected by texture, a small number of impurities or absorption (we try to minimise texture using transmission experiments in DSH geo- metry). In our case, structure solutions were achieved when very short wavelength synchrotron radiation measurements were available for us. As we know, the precision of powder diffraction structure is definitely less than that of structures solved from single crystal data; however, these data, in many cases, are all that we can obtain. Moreover, for many applications these data are sufficient. In this paper, we describe two structures created by new hybrid materials. Even using powder diffraction data, we can solve beau- tiful crystal structures with astonishing crystal architectures. With a crystal structure at hand, we can predict certain properties of * Correspondence to: M. Grzesiak-Nowak, Jerzy Haber Institute of Catalysis and Surface Chemistry PAS, ul. Niezapominajek 8, Kraków 30-239, Poland. a Jerzy Haber Institute of Catalysis and Surface Chemistry PAS, ul. Niezapominajek 8, Kraków 30-239, Poland b HASYLAB, Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, Hamburg D-22607, Germany c Faculty of Chemistry, Jagiellonian University, ul. Ingardena 3, Kraków 30-060, Poland X-Ray Spectrom. (2015) Copyright © 2015 John Wiley & Sons, Ltd. Special issue article Published online in Wiley Online Library (wileyonlinelibrary.com) DOI 10.1002/xrs.2647