Wearing Gigantic Silver Armor on Transition‐Metal‐Containing Polyoxometalates: Formation of Supertetrahedral Intercluster Compounds

Abstract Compared to versatile polyoxometalate (POM)‐templated Ag clusters, the construction of closed Ag clusters using transition‐metal‐containing polyoxometalates (TMCPOMs) as anionic templates has, to our knowledge, never been reported. In this work, we have synthesized three TMCPOM‐templated gigantic closed Ag clusters, [{(Co 0.58 W 0.42 ) 3 (OH) 3 (Ag 0.5 O 3 )(SiW 9 O 34 )} 4 @Ag 114 Br 4 ( t BuC≡C) 72 ]·[SiW 12 O 40 ] 2 ·10CH 3 CN ( 1 ), [{(Cu 0.58 W 0.42 ) 3 (OH) 3 (Ag 0.5 O 3 )(SiW 9 O 34 )} 4 @Ag 114 Br 4 ( t BuC≡C) 72 ]·[SiW 12 O 40 ] 2 ( 2 ), and [{(Co 0.58 W 0.42 ) 3 (OH) 3 (Ag 0.5 O 3 )(GeW 9 O 34 )} 4 @Ag 114 Br 4 ( t BuC≡C) 72 ]·[GeW 12 O 40 ] 2 ( 3 ), using a universal one‐pot solvothermal synthetic approach. Single‐crystal X‐ray diffraction analyses demonstrate that the high‐nuclearity transition metal‐containing (M = Co/Cu) POMs with idealized T d symmetry are closely covered by gigantic Ag armors, representing the largest TMCPOM‐templated closed Ag clusters to date. Moreover, compounds 1 − 3 can form interesting supertetrahedral intercluster packing structures through Columbic and hydrogen bonding interactions between the cationic TMCPOM‐templated gigantic {Ag 114 } clusters and the counter [XW 12 O 40 ] 4− (X = Si/Ge) anions. Upon light irradiation, all three compounds exhibited decent photocatalytic CO 2 reduction activity, which is dependent on their different electronic structures.