Interaction of the electrophilic bis(pentafluorophenyl)iodonium cation [(C6F5)2I]+ with the ambident pseudohalogenide anions [SCN]− and [CN]

• Published in: Journal of fluorine chemistry 2014-07, Vol.163, p.28-33
• Main Authors: Hirschberg, Markus E., Barthen, Peter, Frohn, Hermann-Josef, Bläser, Dieter, Tobey, Briac, Jansen, Georg
• Format: Article
• Language: English
• Subjects: Ab initio computations; Ambident pseudohalides; Anion metathesis; Bis(pentafluorophenyl)iodonium salts; Molecular structure
• ISSN: 0022-1139; 1873-3328
• DOI: 10.1016/j.jfluchem.2014.04.006

The iodonium pseudohalides [(C6F5)2I][X] (X=CN and SCN) result from reactions of [(C6F5)2I][F] with (CH3)3Si–CN or (CH3)3Si–NCS, respectively and form oligomers in solution. Dimeric [(C6F5)2I][SCN] is characterized by its single crystal structure. •An efficient anion metathesis approach to new iodonium salts is offered by reaction of [(C6F5)2I][F] with (CH3)3SiX (X=CN and NCS).•Monomeric [(C6F5)2I][X] tends to associate in the gas phase, in coordinating solvent solutions, and in the solid state.•Intrinsically unstable [(C6F5)2I][X] shows a clean decomposition to equimolar amounts of C6F5I and C6F5X. The iodonium pseudohalide compounds, [(C6F5)2I][X] (X=SCN and CN) were synthesized by means of fluoride substitution in [(C6F5)2I][F] with the Lewis acidic reagents (CH3)3Si–NCS and (CH3)3Si–CN. The isolated iodonium pseudohalides are intrinsically unstable solids. Decomposition resulted in equimolar amounts of C6F5I and C6F5SCN or C6F5I and C6F5CN, respectively. In case of [(C6F5)2I][SCN] single crystals could be grown from CH2Cl2. The crystal structure revealed a dimer with an eight membered ring formed by two ambident anions bridging the iodine atoms of two cations by N and S coordination. The favored dimerization of [(C6F5)2I][SCN] and [(C6F5)2I][CN] in the gas phase is supported by ab initio computations.