Inorganic Chemistry, Vol.58, No.7, 4244-4252, 2019
Control of Lambda- and Delta-Isomerization of the Atrane Cages in Group XIV Metallatranes by Chiral Axial Substituents
The syntheses of the novel stannatranes N(CH2CMe2O)(3)Sn-(1S)-(-)-OC(O)C(OMe)(CF3)(C6H5), 1(S, Delta), and N(CH2CMe2O)(3)Sn-(1R)-(-O-OC(O)C(OMe)(CF3)(C6H5), 2(R, A), and germatranes N(CH2CMe2O)3Ge-(1S)-(O)-OC(O)C(OMe)(CF3)(C6H5), 3(S, A), and N(CH2CMe2O)(3)Ge-(1R)-(+)-OC(O)C(OMe)(CF3)(C6H5), 4(R, A) (with 1, S, A-configured/2, R, A configured and 3, S, A-configured/4, R, A-configured being pairs of enantiomers) are reported. The compounds were characterized by NMR and IR spectroscopy, electrospray ionization mass spectrometry, and single crystal X-ray diffraction analysis. The epimerization via A A ring flip of the enantiomeric stannatrane pair 1(S, A)/2(R, A) was investigated by NMR experiments at variable temperatures and density functional theory (DFT) calculations.