title: 1,3,5-Tri(iodoethynyl)-2,4,6-trifluorobenzene: halogen-bonded frameworks and NMR spectroscopic analysis.
abstract: Halogen bonding is the non-covalent interaction between the region of positive electrostatic potential associated with a covalently bonded halogen atom, named the σ-hole, and a Lewis base. Single-crystal X-ray diffraction structures are reported for a series of seven halogen-bonded cocrystals featuring 1,3,5-tris(iodoethynyl)-2,4,6-trifluorobenzene (1) as the halogen-bond donor, and bromide ions (as ammonium or phosphonium salts) as the halogen-bond acceptors: (1)·MePh3PBr, (1)·EtPh3PBr, (1)·acetonyl-Ph3PBr, (1)·Ph4PBr, (1)·[bis(4-fluorophenyl)methyl]triphenylphosphonium bromide, and two new polymorphs of (1)·Et3BuNBr. The cocrystals all feature moderately strong iodine-bromide halogen bonds. The crystal structure of pure [bis(4-fluorophenyl)methyl]triphenylphosphonium bromide is also reported. The results of a crystal engineering strategy of varying the size of the counter-cation are explored, and the features of the resulting framework materials are discussed. Given the potential utility of (1) in future crystal engineering applications, detailed NMR analyses (in solution and in the solid state) of this halogen-bond donor are also presented. In solution, complex13C and19F multiplets are explained by considering the delicate interplay between various J couplings and subtle isotope shifts. In the solid state, the formation of (1)·Et3BuNBr is shown through significant13C chemical shift changes relative to pure solid 1,3,5-tris(iodoethynyl)-2,4,6-trifluorobenzene.
authors.affiliation: Department of Chemistry and Biomolecular Sciences and Centre for Catalysis Research and Innovation, University of Ottawa, 10 Marie Curie Private, Ottawa, Ontario K1N 6N5, Canada.
authors.forename: Patrick M J
authors.initials: PM
authors.lastname: Szell
authors.affiliation: Department of Chemistry and Biomolecular Sciences and Centre for Catalysis Research and Innovation, University of Ottawa, 10 Marie Curie Private, Ottawa, Ontario K1N 6N5, Canada.
authors.forename: Bulat
authors.initials: B
authors.lastname: Gabidullin
authors.affiliation: Department of Chemistry and Biomolecular Sciences and Centre for Catalysis Research and Innovation, University of Ottawa, 10 Marie Curie Private, Ottawa, Ontario K1N 6N5, Canada.
authors.forename: David L
authors.initials: DL
authors.lastname: Bryce
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D001965:Bromides / Q000737:chemistry; D002722:Chlorobenzenes / Q000737:chemistry*; D003460:Crystallization; D018360:Crystallography, X-Ray; D007454:Iodides / Q000737:chemistry; D007462:Iodobenzenes / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy
chemical_list: D000480:Alkynes; D001965:Bromides; D002722:Chlorobenzenes; D007454:Iodides; D007462:Iodobenzenes; C054509:iodobromine
keywords: NMR spectroscopy; X-ray diffraction; crystal engineering; halogen bond; iodine; isotope shift