Possible role of relativistic effects in the plasticity of the coordination geometry of cadmium(II). A voltametric study of the stability of the complexes of cadmium(II) with 12-crown-4, 15-crown-5 and 18-crown-6 in aqueous solution and the structures of [Cd(benzo-18crown-6)(NCS)(sub 2)] and [K(18-crown-6)][Cd(SCN)(sub 3)]

The voltametric and crystallographic study of complexes of Cd(II) with the crown ethers 12-crown-4, 15-crown-5, and 18-crown 6 is reported. Cd(II) forms stable complexes with the crown ethers 12-crown-4, 15-crown-5, and 18-crown 6, with a remarkable ability of the Cd(II) to bind strongly to these crowns of very different sizes.