{Ti12} Cluster-Added Poly(polyoxometalate) Containing Mixed Trivacant Keggin and Dawson Fragments

A new high-nuclear Ti-oxo-cluster-added poly(polyoxometalate) Cs 2 Na 19 H 12 [(Cs@Ti 12 O 18 )@{( A -α-SiW 9 O 34 ) (P 2 W 15 O 56 ) 3 }]·29H 2 O ( 1 ) has been made by reacting two types of trivacant precursors with TiOSO 4 under hydrothermal conditions. The polyoxoanion of 1 contains one Keggin-type [ A -α-SiW 9 O 34 ] 10– and three Dawson-type [P 2 W 15 O 56 ] 12– fragments that synergistically induce the Ti 4+ ions to aggregate at vacant sites, resulting in a large {Ti 12 }-oxo-cluster cavity sealing a Cs + ion. It is worth noting that the {Ti 12 } cluster is built by three edge-shared Ti 3 O 13 ({Ti 3 } 1 ) cores and one corner-shared Ti 3 O 15 ({Ti 3 } 2 ) core bridged via 6 μ 2 -O, which has never been seen before in polyoxometalate chemistry. Significantly, 1 represents the first example of [ A -α-SiW 9 O 34 ] 10– and [P 2 W 15 O 56 ] 12– simultaneously participating in making poly(polyoxometalate).