Assembly of Saturated Nb/W Mixed‐Addendum Polyoxometalate [P₂W₁₅Nb₃O₆₂]^9– and Lanthanide Ions (Ln = Eu, Ce)

Abstract

Abstract Two isostructural polyoxotungstates, K 6 Na 4 H 8 [Eu 6 (H 2 O) 38 (P 2 W 15 Nb 3 O 62 ) 4 ] · 45H 2 O ( 1 ) and K 6 Na 4 H 8 [Ce 6 (H 2 O) 38 (P 2 W 15 Nb 3 O 62 ) 4 ] · 56H 2 O ( 2 ), have been synthesized by reactionof saturated Nb/W mixed‐addendum polyoxometalate [P 2 W 15 Nb 3 O 62 ] 9– and lanthanide ions in acidic solution. They are the first examples of lanthanide derivatives based on saturated Dawson‐type Nb/W mixed‐addendum polyoxometalates. All the compounds were fully characterized by single‐crystal X‐ray diffraction, IR spectroscopy, thermogravimetric analysis, elemental analysis, and electrochemistry. XRD analysis reveals that 1 and 2 display one‐dimensional chains constructed from sandwich‐type fragment {Ln 3 (P 2 W 15 Nb 3 O 62 ) 2 } linked by alternating Ln–O–W bridging bonds. In 1 and 2 , all the lanthanide ions selectively bind to O t (Nb) of {P 2 W 15 Nb 3 O 62 } fragments (O t : terminal oxygen atoms), indicating the high nucleophilicity of O t (Nb). The photoluminescence behavior of 1 in the solid state was investigated at room temperature; it exhibits the characteristic transition of Eu under the excitation wavelength (394 nm). Additionally, the cyclic voltammogram of 2 indicates good electrocatalytic activity towards the reduction of nitrite.