Syntheses, structures, and stabilities of aliphatic and aromatic fluorous iodine(I) and iodine(III) compounds: the role of iodine Lewis basicity

The title molecules are sought in connection with various synthetic applications. The aliphatic fluorous alcohols R_fnCH₂OH (R_fn = CF₃(CF₂)_n-1; n = 11, 13, 15) are converted to the triflates R_fnCH₂OTf (Tf₂O, pyridine; 22-61%) and then to R_fnCH₂I (NaI, acetone; 58-69%). Subsequent reactions with NaOCl/HCl give iodine(III) dichlorides R_fnCH₂ICl₂ (n = 11, 13; 33-81%), which slowly evolve Cl₂. The ethereal fluorous alcohols CF₃CF₂CF₂O(CF(CF₃)CF₂O)_xCF(CF₃)CH₂OH (x = 2-5) are similarly converted to triflates and then to iodides, but efforts to generate the corresponding dichlorides fail. Substrates lacking a methylene group, R_fnI, are also inert, but additions of TMSCl to bis(trifluoroacetates) R_fnI(OCOCF₃)₂ appear to generate R_fnICl₂, which rapidly evolve Cl₂. The aromatic fluorous iodides 1, 3-R_f6C₆H₄I, 1, 4-R_f6C₆H₄I, and 1, 3-R_f10C₆H₄I are prepared from the corresponding diiodides, copper, and R_fnI (110-130 °C, 50-60%), and afford quite stable R_fnC₆H₄ICl₂ species upon reaction with NaOCl/HCl (80-89%). Iodinations of 1, 3-(R_f6)₂C₆H₄ and 1, 3-(R_f8CH₂CH₂)₂C₆H₄ (NIS or I₂/H₅IO₆) give 1, 3, 5-(R_f6)₂C₆H₃I and 1, 2, 4-(R_f8CH₂CH₂)₂C₆H₃I (77-93%). The former, the crystal structure of which is determined, reacts with Cl₂ to give a 75:25 ArICl₂/ArI mixture, but partial Cl₂ evolution occurs upon work-up. The latter gives the easily isolated dichloride 1, 2, 4-(R_f8CH₂CH₂)₂C₆H₃ICl₂ (89%). The relative thermodynamic ease of dichlorination of these and other iodine(I) compounds is probed by DFT calculations.