Felton Daniel E, Smith Kyson R, Poole Nicholas A, Cronberger Karl, Burns Peter C
Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA.
Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN 46556, USA.
Chemistry. 2024 May 8;30(26):e202400678. doi: 10.1002/chem.202400678. Epub 2024 Mar 21.
The assembly of molybdenum polyoxometalates (POMs) has afforded large discrete nanoclusters with varied degrees of reduction such as the ~20 % reduced molybdenum blues. While many heterometals have been incorporated into these clusters to afford new properties, uranium has yet to be reported. Here we report the first uranium containing molybdenum blue clusters and the unique properties exhibited by this incorporation. The uranyl ion (UO ) directs formation of MoU, a square POM comprised of two faces connected by eight edge-sharing molybdenum dimers. MoU, a chiral cluster, crystallizes as a racemic mixture and, in the solid state, has a 'negative' charge localized on one face of the cluster opposite the 'positively' charged face of another cluster. Using U(IV) as both heterometal and molybdenum reductant afforded crystals of MoU, a wheel cluster with a heptamolybdate cap on one face. MoU dissociates in solution, losing the heptamolybdate, to form MoU. Using more solvent during synthesis afforded crystals of MoUS which, instead of heptamolybdate, contains four sulfate ions. Crystals of MoUS undergo a dehydration induced phase change where clusters form a sheet through oxide bridges. Half of the bridges are cation-cation interactions between the uranyl oxygen atom and molybdenum, the first reported of this kind.
多金属氧酸盐（POMs）钼的组装产生了具有不同还原程度的大型离散纳米团簇，例如约20%还原的钼蓝。虽然许多杂金属已被纳入这些团簇以赋予新的性质，但铀尚未见报道。在此，我们报道了首例含铀的钼蓝团簇以及这种掺入所展现的独特性质。铀酰离子（UO ）引导形成MoU，这是一种方形POM，由通过八个边共享钼二聚体相连的两个面组成。MoU是一种手性团簇，以外消旋混合物形式结晶，并且在固态下，其“负”电荷位于团簇的一个面上，与另一个团簇的“正”电荷面相对。使用U(IV)作为杂金属和钼还原剂得到了MoU的晶体，这是一种在一个面上带有七钼酸帽的轮状团簇。MoU在溶液中解离，失去七钼酸，形成MoU。在合成过程中使用更多溶剂得到了MoUS的晶体，其不含七钼酸，而是含有四个硫酸根离子。MoUS的晶体经历脱水诱导的相变，其中团簇通过氧化物桥形成薄片。一半的桥是铀酰氧原子与钼之间的阳离子 - 阳离子相互作用，这是首次报道此类相互作用。
