Construction of crystal structures of metal(II)–benzoates (M = Mn, Ni, Co, Cu, Zn, and Cd) and 1,2-bis(4-pyridyl)ethane: Effects of metal coordination modes and their catalytic activities

Abstract

Five polymeric metal(II)–benzoate complexes of formula [Mn(O 2CPh) 2(CH 3OH) 2(bpa)] n ( 1-Mn), [Co(O 2CPh) 2(H 2O)(bpa) 1.5] n ( 2-Co), [Ni(O 2CPh) 2(H 2O)(bpa) 1.5] n ( 3-Ni), [Cu(O 2CPh) 2(CH 3OH) 2(bpa)] n ( 4-Cu), and [Cd(O 2CPh) 2(bpa) 1.5] n ( 6-Cd) have been synthesized and characterized (bpa = 1,2-bis(4-pyridyl)ethane). They showed two kinds of structures: parallelogram-like two-dimensional sheets for Co, Ni, and Cd, and one-dimensional chains for Mn, Cu, and Zn. Since similar structures provide similar coordination geometries, the structures depend on the coordination geometries of metal ions. The compounds 1-Mn, 2-Co, 4-Cu, 5-Zn, and 6-Cd have catalyzed efficiently the transesterification of a variety of esters, while 3-Ni has displayed a very slow conversion. The reactivity of catalyst 6-Cd containing Cd ion, well known as an inert metal ion for the ligand substitution, was found to be comparable to that of 5-Zn. The reactivities of the compounds used in this study are in the order of 5-Zn > 6-Cd > 1-Mn > 4-Cu > 2-Co ≫ 3-Ni, indicating that the non-redox metal-containing compounds ( 5-Zn and 6-Cd) show better activity than the redox-active metal-containing compounds ( 1-Mn, 4-Cu, 2-Co, and 3-Ni).