An Innovative Method to Generate Iodine(V and III)-Fluorine Bonds and Contributions to the Reactivity of Fluoroorganoiodine(III) Fluorides and Related Compounds
This dissertation offers at least four new contributions to chemical science: (1) A new method of generation iodofluorides and organoiodofluorides, in which a simple, general and industrial applicable route to I-F compound was developed. This method is suitable for the synthesis of IF5, organoiodine(III) fluorides, and -(V)fluorides. The convenient method is characterised by an oxygen-fluorine substitution process using anhydrous HF (aHF) or aqueous HF in a two phase system. (2) The first synthesis of perfluoroalkenyl(aryl)iodonium tetrafluoroborate salts is reported. The salts result from the reaction of (difluoroiodo)arenes (ArIF2) generally with organodifluorboranes to yield the corresponding organo(aryl)iodonium tetrafluoroborates in good yields and high purity. The iodonium salts were investigated spectroscopically and structurally. (3) Key reactivities of monofluoro(difluoroiodo)benzenes are investigated. The reactions of (difluoroiodo)arenes (Ar = o-, m-, p-C6H4F) with n [N(CH3)4]F (n = 0.5, 1, 2, 3), CsF (n = 1, 2), 2,2´-bipyridine, and different kind of alcohols (CH3OH, CH3CH2OH and CF3CH2OH) and protonic acids (CF3CO2H, HF) were examined. The solid structure of ArIF2 (Ar = o-, p-C6H4F) was investigated which show strong intermolecular contacts between the positively charged iodine centre and negatively charged fluorine atoms of the IF2 group of neighbour molecules. Zigzag arrangements result in case of the para and ortho isomers. (4) Introduction concerning the reactivity of perfluoroalkenyl(aryl)iodonium tetrafluoroborate salts were performed. The reactions of perfluorovinyl(aryl)iodonium tetrafluoroborate salts with [N(CH3)4]F in dichloromethane show that the metathesis of the tetrafluoroborate anion by fluoride was accompanied by the spontaneous decomposition even at low temperature. The reaction of [trans-CF3CF=CF(aryl)I][BF4] with weak but oxidisable Lewis bases such as (p-C6H4F)3As or (p-C6H4F)3P emphasise the preparative potential of perfluoroalkenyl-(aryl)iodonium salts to enable the electrophilic alkenylation of nucleophiles. In the present case [trans-CF3CF=CF(p-C6H4F)3As][BF4] and [trans-CF3CF=CF(p-C6H4F)3P][BF4] were formed in a mixture of by-products. In the crystal structure of the alkenyl(aryl)iodonium tetrafluoroborate salt a pronounced cation anion interaction was found which lead to a three-dimensional network.