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(f)(n)CH(2)OH (R(f)(n) = CF(3)(CF(2))(n)(–1); n = 11, 13, 15) are converted to the triflates R(f)(n)CH(2)OTf (Tf(2)O, pyridine; 22–61%) and then to R(f)(n)CH(2)I (NaI, acetone; 58–69%). Subsequent reactions with NaOCl/HCl give iodine(III) dichlorides R(f)(n)CH(2)ICl(2) (n = 11, 13; 33–81%), which slowly evolve Cl(2). The ethereal fluorous alcohols CF(3)CF(2)CF(2)O(CF(CF(3))CF(2)O)(x)CF(CF(3))CH(2)OH (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(f)(n)I, are also inert, but additions of TMSCl to bis(trifluoroacetates) R(f)(n)I(OCOCF(3))(2) appear to generate R(f)(n)ICl(2), which rapidly evolve Cl(2). The aromatic fluorous iodides 1,3-R(f6)C(6)H(4)I, 1,4-R(f6)C(6)H(4)I, and 1,3-R(f10)C(6)H(4)I are prepared from the corresponding diiodides, copper, and R(f)(n)I (110–130 °C, 50–60%), and afford quite stable R(f)(n)C(6)H(4)ICl(2) species upon reaction with NaOCl/HCl (80–89%). Iodinations of 1,3-(R(f6))(2)C(6)H(4) and 1,3-(R(f8)CH(2)CH(2))(2)C(6)H(4) (NIS or I(2)/H(5)IO(6)) give 1,3,5-(R(f6))(2)C(6)H(3)I and 1,2,4-(R(f8)CH(2)CH(2))(2)C(6)H(3)I (77–93%). The former, the crystal structure of which is determined, reacts with Cl(2) to give a 75:25 ArICl(2)/ArI mixture, but partial Cl(2) evolution occurs upon work-up. The latter gives the easily isolated dichloride 1,2,4-(R(f8)CH(2)CH(2))(2)C(6)H(3)ICl(2) (89%). The relative thermodynamic ease of dichlorination of these and other iodine(I) compounds is probed by DFT calculations.