A Wavy Multiple Tm(III)-Containing Open Wells–Dawson Silicotungstate: Synthesis, Structure, and Catalytic Application
Guo‐Ping Yang, Jiawei Cao, Yu Xiao, Qi-Long Hu, Haoqi Liu, Xiaohong Cao, Ke Li, Yalin Zhang, Xin‐Xiong Li
Abstract
A Tm(III)-rich silicotungstate Na{Tm 3 (H 2 O) 17 [Tm 2 (H 2 O) 7 (Si 2 W 18 O 66 )]}·35H 2 O ( Tm 5 Si 2 W 18 ) based on the open Wells–Dawson-type [Si 2 W 18 O 66 ] 16- building unit was synthesized by the reaction of Na 10 [α-SiW 9 O 34 ]·18H 2 O, itaconic acid, and TmCl 3 in a HAc/NaAc buffer solution. Five kinds of Tm(III) ions were found in this compound and further linked the {Tm 2 Si 2 W 18 } subunit to form an interesting wavy 1D chain structure, which achieved the introduction of more lanthanide (Ln) ions into the [Si 2 W 18 O 66 ] 16- unit for the first time. Tm 5 Si 2 W 18 contains multiple exposed Tm-metal active sites, making it an efficient catalyst for the acetalization of 2-aminobenzamides/2-aminobenzenesulphonamides with aldehydes. A series of 2,3-dihydroquinazolinones and 3,4-dihydro-2 H -1,2,4-benzothiadiazine-1,1-dioxides could be obtained in excellent yields under green and mild conditions.