Preparation and Properties of Trifluoromethylated Aryl Derivatives of Germanium, Tin, and Lead. High-Yield Syntheses of Trifluoromethylbenzene

Abstract

Ligand exchange reactions of Cd(CF3)2·glyme with a number of aryl-containing Pb, Sn, and Ge halides, acetates, and thioethers were examined in THF or CHCl3. With an excess of trifluoromethylating agent and relatively lengthy reaction times, complete displacement of the halides or halide equivalents from the group 14 centers was observed, and the new compounds PbPh(CF3)3, 51%, PbPh2(CF3)2, 61%, PbPh3CF3, 81%, SnPh2(CF3)2, 55%, SnPh3CF3, 80%, and GePh3CF3, 72%, were isolated and characterized. With shorter reaction times and/or with the trifluoromethylating agent as the limiting reactant, partial substitution predominated, and the new species PbPh2(Cl)CF3, 78%, PbPh2(O2CCH3)CF3, 89%, PbPh(O2CCH3)2CF3, 63%, and PbPh(O2CCH3)(CF3)2, 64%, were separated. In addition, two preliminary studies of the reactivity of aryl−group-IVA compounds were carried out. In the first, ligand exchanges of PbPh3CF3 with a representative main group and transition metal complex were probed; Sb(CF3)3, 61%, and Pd(PEt3)2(Cl)CF3, 62%, were generated. In the second, the feasibility of forming aryl−CF3 species in high yields via CuCl-mediated M−Ph cleavages was examined. In these reactions PhCF3 was isolated from M2Ph6 in yields of 95% (M = Pb), 96% (M = Sn), and 58% (M = Ge).