Synthesis, crystal and molecular structure, and stereochemical nonrigidityof bis[(N-methylacetamido)methyl]dichlorogermane and -stannane

Previously unknown (O-Ge)-bischelate bis[(N-methylacetamido)methyl]dichloro germane and (O-Sn)-bischelate bis[(N-methylacetamido)methyl]dichlorostannan e were prepared, respectively, by reaction of N-trimethylsilyl-N-methylacet amide with bis(chloromethyl)dichlorogermane and by direct reaction of metal lic tin with N-methyl-N-chloromethylacetamide. The single-crystal X-ray dif fraction study showed that the germanium and tin atoms are coordinated octa hedrally, with the carbon atoms in trans positions and coordinating oxygen atoms and chlorine atoms, in cis positions relative to each other. The geom etric parameters of the central coordination cores in these dichlorides wer e compared with those of the previously described complexes with bidentate lactamomethyl ligands. According to the H-1, C-13, and Sn-119 NMR data, the hexacoordination of the central atom and the geometry of the coordination entity are preserved in solution at low temperatures; at higher temperature s a stereodynamic process occurs, making isochronous the signals of the NCH 2M protons (M = Ge, Sn).