Giant Polytungstoarsenate Clusters Derived from New [As₄W₁₉O₆₈(H₂O)]^14–Building Blocks

A new compound K8Na4[As4W19O69]center dot 19.5H(2)O (1), which can be described as an extended structure of [As2W19O67(H2O)](14-), was synthesized and used as building blocks to construct the high nuclear polytungstoarsenate cluster K10Na8[(W13O28)(H2O)(6)(OH)(4)(AsW9O33)(4)]center dot 56H(2)O (2). Polyoxoanion 2 is composed of four trivacant Keggin B-alpha-type [AsW9O33] units encapsulating a unique polytungstate cluster W13O32(OH)(4)(H2O)(6), which has never observed in the polyoxometalate chemistry. Electrocatalytic studies indicate that compound 2 displays electrocatalytic activity toward the reduction of nitrate.