Discovery and Isolation of Two Arsenotungastate Species: [As 4 W 48 O 168 ] 36- and [As 2 W 21 O 77 (H 2 O) 3 ] 22 .

Two novel arsenotungstate species, [As 4 W 48 O 168 ] 36- ( 1a ) and [As 2 W 21 O 77 (H 2 O) 3 ] 22- ( 2a ), have been successfully isolated under a one-pot synthetic method. 1a is the second largest arsenotungstate cluster and is constructed from four {AsW 12 } clusters combined together. 2a can be described as lacunary sites of {As 2 W 19 } filled by {W 2 O 8 } units. Compounds 1 and 2 exhibit proton conductivity properties, and the conductivity value of 1 is 5.0 × 10 -3 S cm -1 at 98% relative humidity and 75 °C. This work proves that the lattice water molecules and polyoxoanions can participate in the formation of a hydrogen bond, acting as effective pathway for intermolecular proton conduction.