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Homocoupling Reaction of Aryl Halides Catalyzed by Metal Cations in Isostructural Coordination Polymers

Research paper by Li’an Guo, Chao Huang, Lu Liu, Zhichao Shao, Yue Tong, Hongwei Hou, Yaoting Fan

Indexed on: 11 Aug '16Published on: 03 Aug '16Published in: Crystal Growth & Design



Abstract

A series of two-dimensional layered isostructural coordination polymers have been successfully isolated under solvothermal conditions by the reaction of a pyridine carboxylic ligand together with M2+ (M = Mn, Co, Ni, Cu) salts. The difference of central metals leads to isostructural M frameworks showing different catalytic activity for the synthesis of biaryl derivatives. Density functional theory was performed for the balanced geometry structures, net charges of atoms, and energy of frontier molecule orbits. By this method we explain the influence of central metal ions on the catalytic performance.We have obtained a suite of two-dimensional layered isostructural coordination polymers [M(pypa)2(H2O)2]n (M = Mn (1), Co (2), Ni (3), Cu (4), respectively), Hpypa = 1H-[3-(4-pyridy)pyrazole]propionic acid), and used them in catalyzing the homocoupling of aromatic halides. 3 and 4 exhibit preeminent catalytic performance on the homocoupling of aryl bromide or aryl iodide without byproducts, while 2 only promoted the homocoupling of aryl iodide. But 1 showed no catalytic activities for all tested aromatic halides. Subsequently, density functional theory was performed for the balanced geometry frameworks, net charges of atoms, and energy of frontier molecule orbits. By using this method we determined that the catalytic performance was influenced by central metal ions. For further improving the catalytic performance, polyvinylpyrrolidone or polyethylene glycol 20000 (PEG 20000) was used as surfactants to synthesize the microscales of 3’s (3a and 3b). 3a and 3b showed more preeminent catalytic activity than 3.

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