Liang Guang-Ming, Xiong Peng, Azam Khan, Ni Qing-Ling, Zeng Jian-Qiang, Gui Liu-Cheng, Wang Xiu-Jian
School of Chemistry and Pharmaceutical Sciences , Guangxi Normal University , Guilin 541004 , People's Republic of China.
Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, College of Chemistry and Chemical Engineering , China West Normal University , Nanchong 637002 , People's Republic of China.
Inorg Chem. 2020 Feb 3;59(3):1653-1659. doi: 10.1021/acs.inorgchem.9b02763. Epub 2020 Jan 22.
A discrete tetrahedral indium cage, {[In(μ-OH)(HCO)(tcma)]} (In-GL), was synthesized solvothermally by the reaction of indium nitrate with the tripodal tricarboxylic acid ligand ,,-tris{(2'-carboxy[1,1'-biphenyl]-4-yl)methyl}methylammonium chloride ([Htcma]Cl). This cage consists of four trimeric units [In(μ-OH)(μ-CO)(μ-HCO)] and four [tcma] ligands, which all perform as 3-connection nodes to bridge each other, resulting in a tetrahedral cage structure. The trimeric unit [In(μ-OH)(μ-CO)(μ-HCO)] is observed for the first time in the family of In-based metal-organic structures and can be considered as an evolution of a 6-connected [In(μ-O)(μ-CO)] unit. Each In is terminally coordinated by a μ-HCO group. This cage contains potential Lewis acidic/basic active sites endowed by In ions as Lewis acidic sites and the uncoordinated oxygen atoms of μ-HCO moieties as Lewis basic sites and was explored as an effective heterogeneous catalyst in the cycloaddition of CO with epoxides and the Strecker reaction for amino nitriles. These catalytic reactions were deduced to happen on the surface of the In-GL cage.
