Crystal and molecular structures of six-coordinate germanium difluorides and dibromides containing lactamomethyl C,O-chelating ligands

The structures of (O-Ge)-bischelate bis(lactamomethyl)difluoro- and -dibrom ogermanes [L-(n)](2)GeX2, where L is the bidentare lactamomethyl C,O-chelat ing ligand, n = 5-7 (the size of the lactam ring), and X = F or Br, were st udied by X-ny diffraction analysis. The six-coordinate Ge atom in these com pounds is involved in two hypervalent X-Ge-O bonds whose parameters are com pared with the corresponding values in analogous dichlorides and five-coord inate Ge derivatives. On going from difluorides to dichlorides and then to dibromides, the coordination environment about the Ge atom approaches the i deal octahedron. An analogous effect is observed as the size of the lactam ring increases.