A Giant 3d-4f Polyoxometalate Super-Tetrahedron with High Proton Conductivity.

The assembly of gigantic heterometallic metal clusters remains a great challenge for synthetic chemistry. Herein, based on the slow release strategy of lanthanide ions and in situ formation of lacunary polyoxometalates, two giant 3d-4f polyoxometalate inorganic clusters [LaNi12 W35 Sb3 P3 O139 (OH)6 ]23- (LaNi12 ) and [La10 Ni48 W140 Sb16 P12 O568 (OH)24 (H2 O)20 ]86- (La10 Ni48 ) are obtained. The nanoscopic inorganic cluster La10 Ni48 possesses a super tetrahedron structure, which can be viewed as assembly from four LaNi12 molecules encapsulating a central [La6 (SbO3 )4 (H2 O)20 ]6+ octahedron core. This giant aesthetic La10 Ni48 tetrahedron containing 214 metal ions is the largest 3d-4f cluster reported thus far in polyoxometalate system. More interestingly, the LaNi12 and La10 Ni48 display high stability in solution and La10 Ni48 displays excellent proton conductivity.