Through reactions of 1,2-disila[12]crown-4 or 1,2-disila-benzo[12]crown-4 ethers with BeCl2 eight-membered Be–O-heterocycles, which are annulated by two six-membered Be–O-cycles were obtained and characterised. The reactions leading to these unusual ring systems have been investigated by NMR and IR spectroscopy as well as reactions with further ligand derivatives.
