TRIFLUOROMETHYL-SUBSTITUTED PLUMBANES - SYNTHESIS, PROPERTIES AND NMR-SPECTRA OF COMPOUNDS (CF3)NPBR4-N (N = 1-3) AND (CF3)NPBR3-NX (N = 1, 2, R = ME, ET, X = HAL)

Trifluoromethylated derivatives of lead, (CF3)nPbR4-n (n = 1-3; R = CH3, C2H5), have been prepared by a stepwise halide/CF3 exchange from (CF3)nPbR3-nX (n = 0-2) and donor-stabilized (CF3)2Cd. Upon treatment of CF3PbR3 and (CF3)2PbR2 with halides under mild conditions, selective cleavage of the Pb-C(H) bond and formation of the corresponding alkyl(trifluoromethyl)haloplumbanes were achieved, whereas with (CF3)3PbMe only (CF3)2PbMeX was obtained. The direct exchange of alkyl and trifluoromethyl groups was observed for the systems PbR4/(CF3)nE (E = Hg, Ge, Sn), (CF3)4Sn being the most efficient CF3 transfer reagent. All compounds were characterized by vibrational, mass and multinuclear NMR spectroscopy. The NMR coupling constants (n)J(Pb-207-E) (E = F-19, H-1, C-13), which vary strongly with solvents and substituents, have been determined along with their absolute signs. Linear correlations were found between 1J(Pb-207-CF3) and 2J(Pb-207-F) or 2J(Pb-207-F) and 2J(Sn-119-F) of homologous trifluoromethylated stannanes, respectively.