Poly[(μ4-2,5-dimethoxybenzene-1,4-dicarboxylato)manganese(II)] and its zinc(II) analogue: three-dimensional coordination polymers containing unusually coordinated metal centres
摘要:
The title compounds, [Mn(C10H8O6)] (n) and [Zn(C10H8O6)] (n) , are isomorphous coordination polymers prepared from 2,5-dimethoxyterephthalic acid (H(2)dmt) and the respective metal(II) salts. Both complexes form three-dimensional metal-organic frameworks with each M II centre bridged by four 2,5-dimethoxyterephthalate (dmt2-) anions, resulting in the same type of network topology. The asymmetric unit consists of one M II cation on a twofold axis and one half of a dmt2- anion (located on a centre of inversion). In the crystal structure, the M II centres are coordinated in a rather unusual way, as there is a distorted tetrahedral inner coordination sphere formed by four carboxylate O atoms of four different dmt2- anions, and an additional outer coordination sphere formed by two methoxy and two carboxylate O atoms, with each of the O atoms belonging to one of the four different dmt2- anions forming the inner coordination sphere. Consideration of both coordination spheres results in a super-dodecahedral coordination geometry for the M II centres. Besides the numerous M II...O interactions, both structures are further stabilized by weak C-H...O contacts.