The transannular interaction germanium–nitrogen in germocanes: The influence of substituents

The reaction of RN(CH2CH2OH)CHR1CR2R3OH (1–8) with a stoichiometric amount of tetrachloro(bromo)germane leads to the corresponding RN(CH2CH2O)(CHR1CR2R3O)GeHal2 (9–21). Difluorenylgermocane 22 was prepared by treatment of diethoxydifluorenylgermane with N-methyldiethanolamine. Different dialkanolamines were found to be successive precursors of dimethylgermocanes, RN(CH2CH2O)(CHR1CR2R3O)GeMe2 (23–26). The chemical properties of simple and easy to access germocanes RN(CH2CH2O)2GeX2 [X = OH, Br (28), Cl (29)] were studied and the difluoro (27), haloalkoxy (30–32), and dialkoxy (33, 34) derivatives were prepared. The structures of the compounds 16, 20–22, and 26 were confirmed by X-ray diffraction and the structural features in solution of 23 and 26 were studied by NMR spectroscopy (NOEs). The relationship between the nature of substituents at different positions of the germocane skeleton and the strength of the intramolecular Ge ← N bond is discussed.