Beryllium Crown Ether Complexes Reinvestigated

The species present in solutions of [12]crown‐4, [15]crown‐5, and [18]crown‐6 complexes with BeCl 2 were investigated by 1 H, 13 C, and 9 Be NMR spectroscopy. These are [(BeCl)([12]crown‐4)] + ( 1 ), [(BeCl 2 )([15]crown‐5)] ( 2 ), and [(BeCl 2 ) 2 ([18]crown‐6)] ( 3 ), however in solution the majority of the crown ethers is not bound to beryllium. In case of [12]crown‐4 and [18]crown‐6 huge amounts of precipitate are formed, which were identified to be [(BeCl)([12]crown‐4)]Cl ( 1a ) and compound 3 , while [15]crown‐5 is capable of dissolving more than one equivalent of BeCl 2 in dichloromethane.