Fig. 1. (a) Crystal structure of 1-Yb. (b) Superimposed structures of 1-Yb (dark-green) and 1-Ca (pink). (c) Crystal structure of 3-Ca. (d) Crystal structure of 7-Ca. All H atoms (except OH and NH hydrogen) are omitted for clarity. In 3-Ca and 7-Ca, the Et and Me groups from BDI* and Am*, respectively, have also been omitted for clarity.
