New Media for Classical Coordination Chemistry: Phase Transfer of Werner and Related Polycations into Highly Nonpolar Fluorous Solvents

Optimized procedures for the previously reported conversions of 1,3-diiodobenzene and perfluorohexyliodide (Rf6I; copper, DMSO, 140 degrees C) to 1,3-C6H4(R-f6)(2) (3; 86-70%) and 3 to Br(3,5-C6H3(R-f6)(2) (2; NBS, H2SO4/CF3CO2H; 88-75%) are described. The latter is converted (t-BuLi, BCl3) to the "fluorous BArf" salt NaB(3,5-C6H3(R-f6)(2))(4) (1 or NaBArf6; 77-70%), as given earlier. When orange aqueous solutions of [Co(en)(3)]Cl-3 (en = ethylenediamine) are treated with perfluoro(methylcyclohexane) (PFMC) solutions of 1 (1:3 mol ratio), the aqueous phase decolorizes and [Co(en)(3)](BArf6)(3) can be isolated from the fluorous phase (96%). Similar reactions with the trans-1,2-cyclohexanediamine analogue [Co(R,R-chxn)(3)]Cl-3 and [Ru(bipy)(3)]Cl-2 give [Co(R,R-chxn)(3)](BArf6)(3) (92%) and [Ru(bipy)(3)] (BArf6)(2) (95%). All of these salts are isolated as hydrates and exhibit toluene/PFMC partition coefficients of <= 1:>= 99, establishing that the anion BArf6- can efficiently transport polar polycations into highly nonpolar fluorous phases. When equal volumes of CH2Cl2 and PFMC are charged with the "nonfluorous" BArf (B(3,5-C6H3-(CF3)(2))(4)) salt [Co(en)(3)](BArf)(3) and 3.0 equiv of the fluorous salt NaBArf6, the cobalt trication partitions predominantly into the fluorous phase (64:36). The arene 2 crystallizes in a polar space group (tetragonal, I4, Z = 8) with fluorous and nonfluorous domains and all eight bromine atoms located essentially on one face of the unit cell.