Syntheses and structures of M–Na (M=Zn, Mn) coordination polymers in which ligands and Na ions exhibit complex coordination modes

Abstract

The novel heteronuclear complexes [Na2Zn(dipic)2(H2O)] n (1) and [Na2Mn(dipic)2(H2O)2] n (2) (H2dipic = pyridine-2,6-dicarboxylic acid) were synthesized and characterized by single-crystal X-ray diffraction, analysis, IR spectroscopy and thermogravimetric analysis. Complex 1 consists of infinite 2D double layers, which are further attached into a 3D network through π–π stacking. All sodium ions are 3-coordinate. Complex 2 has an intricate 3D structure, in which two sodium ions are differently involved in forming polymeric coordination units, and are 3- and 7-coordinate, respectively. Dipic anions act as multidentate ligands showing novel and unprecedented bridging coordination modes. One ligand coordinates to three metal ions and with five bonds; the other coordinates five metal ions with nine bonds.