1102 https://doi.org/10.1107/S2056989019009344 Acta Cryst. (2019). E75, 1102–1107 research communications Received 13 June 2019 Accepted 28 June 2019 Edited by W. T. A. Harrison, University of Aberdeen, Scotland Keywords: crystal structure; perfluoropyridine. CCDC references: 1937619; 1937620; 1937621; 1937622; 1937623 Supporting information: this article has supporting information at journals.iucr.org/e Crystal structures and Hirshfeld surface analysis of a series of 4-O-arylperfluoropyridines Andrew J. Peloquin, Cynthia A. Corley, Sonya K. Adas, Gary J. Balaich and Scott T. Iacono* Department of Chemistry & Chemistry Research Center, United States Air Force, Academy, Colorado Springs, CO 80840, USA. *Correspondence e-mail: scott.iacono@usafa.edu Five new crystal structures of perfluoropyridine substituted in the 4-position with phenoxy, 4-bromophenoxy, naphthalen-2-yloxy, 6-bromonaphthalen-2- yloxy, and 4,4 0 -biphenoxy are reported, viz. 2,3,5,6-tetrafluoro-4-phenoxy- pyridine, C 11 H 5 F 4 NO (I), 4-(4-bromophenoxy)-2,3,5,6-tetrafluoropyridine, C 11 H 4 BrF 4 NO (II), 2,3,5,6-tetrafluoro-4-[(naphthalen-2-yl)oxy]pyridine, C 15 H 7 F 4 NO (III), 4-[(6-bromonaphthalen-2-yl)oxy]-2,3,5,6-tetrafluoropyridine, C 15 H 6 BrF 4 NO (IV), and 2,2 0 -bis[(perfluoropyridin-4-yl)oxy]-1,1 0 -biphenyl, C 22 H 8 F 8 N 2 O 2 (V). The dihedral angles between the aromatic ring systems in I–IV are 78.74 (8), 56.35 (8), 74.30 (7), and 64.34 (19) , respectively. The complete molecule of V is generated by a crystallographic twofold axis: the dihedral angle between the pyridine ring and adjacent phenyl ring is 80.89 (5) and the equivalent angle between the biphenyl rings is 27.30 (5) . In each crystal, the packing is driven by C—HF interactions, along with a variety of C—F , C—H, C—BrN, C—HN, and C—Br contacts. Hirshfeld surface analysis was conducted to aid in the visualization of these various influences on the packing. 1. Chemical context Pentafluoropyridine, or perfluoropyridine (C 5 F 5 N) is one of the most important perfluoroheteroaromatic compounds. It is commercially available and its chemistry is well understood. As a result of the presence of five fluorine atoms, in addition to the nitrogen atom of the pyridine ring, these systems are highly electrophilic and undergo substitution reactions readily in a predictable pattern (Baker & Muir, 2010; Chambers et al. , 1988). This chemistry has already been used in the design of several drugs (Bhambra et al., 2016) and in peptide modifi- cation (Gimenez et al., 2017). In an effort to further under- stand the intermolecular interactions in the solid state of these fluorinated compounds, five new crystal structures of penta- fluoropyridine derivatives are herein reported as well as their syntheses. ISSN 2056-9890