Notably, although the synthesis and crystallization of Ra1 was performed identically to Ba1, the complexes were not isostructural. Ra1 instead crystallized in the triclinic P1 space group, and the conformation of DB30C10 in Ra1 resembled that of Ba2 and Ba3 (Figure ). In this case, the disparate configurations between Ba1 and Ra1 cannot be attributed to the presence of different counteranions in the crystal lattice because both complexes possess two outer-sphere BPh4 -anions. Rather, these results suggest that the size of the M 2+ center plays an important role in the conformation adopted by DB30C10. Specifically, the 8coordinate ionic radii established for Sm 2+ and Ba 2+ are 1.27 Å and 1.42 Å, respectively, whereas the ionic radius of Ra 2+ is 1.48 Å. Thus, we hypothesize that the Ra 2+ ion may be too large to be optimally accommodated by DB30C10 in the "Pac-Man" configuration.