Silver Ion-Induced Formation of Unprecedented Thorium Nonamer Clusters via Lacuna-Construction Strategy

Herein, we report the synthesis and structures of two novel mixed-metal clusters denoted as Th9Ag6 and Th9Ag12. Both clusters feature unprecedented Th-9 cores. The cores are tricapped trigonal prism moieties that are novel among actinides. Attempted alternative synthesis routes indicate that the Th-9 clusters are accessible only through slow introduction of Ag+ into a solution containing a Th-6 cluster modified with 2-picolinic acid. Alternative rapid addition of Ag+ leads to dissociation of the Th-6 cluster with formation of a high-purity (ThAg)(infinity) two-dimensional layered structure material. A mechanism for cluster dissociation and reassembly to yield Th9 from Th6 is proposed that is consistent with spectroscopic observations and computational results. Because of Ag center dot center dot center dot Ag and pi-pi interactions, the Th9Ag12 cluster exhibits high stability in air, at elevated temperature, under gamma-irradiation, and in common solvents.