New {Co <sub>9</sub>} cluster-added banana-shaped polyoxometalate modified by B atom
Hai‐Lou Li, Guo‐Yu Yang
Abstract
A new {Co<sub>9</sub>} cluster added polyoxometalate Cs<sub>3</sub>K<sub>4</sub>Na<sub>5</sub>H<sub>6</sub>[BO(OH)<sub>2</sub>Co<sub>9</sub>O(OH)(H<sub>2</sub>O)<sub>3</sub>(GeW<sub>6</sub>O<sub>26</sub>)(B<em>-α-</em>GeW<sub>9 </sub>O<sub>34</sub>)<sub>2</sub>]·22H<sub>2</sub>O (<strong>1</strong>) has been successfully synthesized in the presence of inorganic boron sources under hydrothermal conditions, and structurally characterized by single-crystal X-ray diffraction, IR spectroscopy, thermogravimetric analysis and powder X-ray diffraction. Compound<strong> 1</strong> represents the first Co-added POM bonded by B atom, and its polyoxoanion is constructed from one hexalacunary GeW<sub>6</sub>O<sub>26</sub> fragment and two trilacunary B<em>-α-</em>GeW<sub>9</sub>O<sub>34</sub> fragments fused together by an unprecedented V-shaped {Co<sub>9</sub>} cluster. Additionally, <strong>1</strong> is an efficient catalyst for accelerating the Knoevenagel condensation of various aldehydes with malonitrile.