Solution <sup>31</sup>P NMR Study of the Acid-Catalyzed Formation of a Highly Charged {U<sub>24</sub>Pp<sub>12</sub>} Nanocluster, [(UO<sub>2</sub>)<sub>24</sub>(O<sub>2</sub>)<sub>24</sub>(P<sub>2</sub>O<sub>7</sub>)<sub>12</sub>]<sup>48–</sup>, and Its Structural Characterization in the Solid State Using Single-Crystal Neutron Diffraction
收藏资源简介：
The first neutron diffraction study of a single crystal containing uranyl peroxide nanoclusters is reported for pyrophosphate-functionalized Na44K6[(UO2)24(O2)24(P2O7)12][IO3]2·140H2O (1). Relative to earlier X-ray studies, neutron diffraction provides superior information concerning the positions of H atoms and lighter counterions. Hydrogen positions have been assigned and reveal an extensive network of H-bonds; notably, most O atoms present in the anionic cluster accept H-bonds from surrounding H2O molecules, and none of the surface-bound O atoms are protonated. The D4h symmetry of the cage is consistent with the presence of six encapsulated K cations, which appear to stabilize the lower symmetry variant of this cluster. 31P NMR measurements demonstrate retention of this symmetry in solution, while in situ 31P NMR studies suggest an acid-catalyzed mechanism for the assembly of 1 across a wide range of pH values.
