A Sandwich Complex of Bismuth Cation and Mono‐Lacunary α‐Keggin‐Type Phosphotungstate: Preparation and Structural Characterisation

We report the first Peacock–Weakley type complexes composed of mono‐lacunary Keggin‐type phosphotungstate, [α‐PW 11 O 39 ] 7– , and Bi 3+ . The self‐assembly reaction between the Keggin‐type phosphotungstate and Bi 3+ in aqueous solution produced Peacock–Weakley type 2:1 ([(PW 11 O 39 ) 2 Bi] 11– , 1 ) and 1:1 ([PW 11 O 39 Bi] 4– , 2 ) complexes depending on the mixing ratio of [α‐PW 11 O 39 ] 7– and Bi 3+ . Studies of both complexes in solution were conducted by different NMR techniques including 31 P and 183 W analyses. Complex 1 was successfully isolated as both tetramethyl ammonium ( 1a ) and potassium ( 1b ) salt, and characterized by single‐crystal X‐ray diffraction, IR spectroscopy and elemental analysis. The sandwich structure of 1a and 1b was determined to be constructed by eight Bi–O bonds with two [α‐PW 11 O 39 ] 7– units.