Synthesis, crystal and molecular structures, and stereochemical nonrigidity of N-(chlorodimethylgermylmethyl)- and N-(bromodimethylgermylmethyl)-N-[(S)-1-phenylethyl]acetamides and N-(chlorodimethylgermylmethyl)-4-phenyl-2-pyrrolidone

Racemic N-(chlorodimethylgermylmethyl)-4-phenyl-2-pyrrolidone and the first optically active amide derivatives containing the asymmetrical carbon atom and the five-coordinate germanium atom, viz., N-(chlorodimethylgermylmethy l)- and N-(bromodimethylgermylmethyl)-N-[(S)-1-phenylethyl]acetamides, were synthesized. Their structures were established by X-ray diffraction analys is. The geometric characteristics of the triponal-bipyramidal valence envir onment about the germanium atoms are compared with those of analogous enant iomeric silicon compounds and the related five-coordinate germanium compoun ds. The barriers to permutational isomerization of the title compounds were determined by dynamic H-1 NMR spectroscopy. It was found that these barrie rs are higher than those of the corresponding silicon analogs.