With these optimal reaction conditions in place, we executed the synthesis of the analogous Ra 2+ complex in a radiological fume hood using 226 Ra(NO3)2 dissolved in D2O. Four large crystals formed after 21 h. One crystal was selected and mounted immediately on the diffractometer using an established protocol (see methods). Analysis of the data acquired by scXRD revealed the complex as [Ra(DB30C10)(H2O)][BPh4]2 (Ra1) (Figure ). Even with the rapid crystallization time of Ra1, the crystals were not colorless as expected, but were instead pale yellow. This yellowing of the crystals was likely due to radiation damage and has also been observed in 226 Ra(SO4) pXRD samples. After 48 hours, the yellow color of the crystals grew more pronounced (Figure ), and additional crystals that formed over this time frame were already degraded to a quality not suitable for scXRD measurements. Collectively, these observations underscore the need for rapid formation and analysis of crystals when working with 226 Ra 2+ . Crystallographic Analysis. Ba1 crystallizes in the monoclinic space group C2/c. The Ba 2+ center is coordinated by all ten etheric oxygen (Oether) donor groups of DB30C10 in a "Pac-Man" configuration (Figure ). In this configuration, the crown ether folds over onto itself, encompassing the metal center. This conformation is further stabilized by ᴨ-ᴨ stacking of the phenyl groups and has been observed previously in an isostructural divalent Sm 2+ complex of DB30C10, [Sm(DB30C10)][BPh4]2•MeCN (Sm1). The crystal structures of two other Ba 2+ complexes of DB30C10 have also been reported. These structures were obtained under different synthetic conditions and crystallized with [Bi2Cl8] - and [Co(NCS)4] -as counteranions, giving rise to complexes with the formulas [Ba(DB30C10)(H2O)][Bi2Cl8] (Ba2) and [Ba(DB30C10)(H2O)][Co(NCS)4]•H2O (Ba3), respectively. In contrast to Ba1, both Ba2 and Ba3 have a water molecule bound to the metal center, forming 11-coordinate complexes. Furthermore, the phenyl groups of DB30C10 are angled away from each other and therefore do not engage in ᴨ-ᴨ stacking. Consequently, Ba2 and Ba3 lack the "Pac-Man" conformation observed in Ba1 and Sm1 (Figure ). These differences suggest that the nature of the counteranion can affect the packing of the crystal structure, resulting in various conformations of DB30C10 around the M 2+ center.