Synthesis, Spectral and Thermal Studies of Bis-2,6 Complexes of Co(II), Ni(II), Cu(II) and Zn(II) Saccharinates: Crystal Structures of [Ni(dmpy)2](sac)2·2H2O and [Zn(dmpy)2](sac)2·2H2O

Abstract

The new transition metal saccharinate complexes of 2,6-dimethanolpyridine (dmpy) have been synthesized and characterized by elemental analyses, magnetic measurements, UV-Vis and IR spectra. Co(II), Ni(II), Cu(II) and Zn(II) form mononuclear octahedral complexes formulated as [M(dmpy)<inf>2</inf>](sac)<inf>2</inf>·H<inf>2</inf>O, where sac is the saccharinate anion. The dmpy ligand coordinates to the metal ions as a tridentate N,O,O′-donor ligand through the amine nitrogen and two hydroxyl oxygen atoms, while the sac ion is present as the counter-ion. The crystal structures of the [Ni(dmpy)<inf>2</inf>](sac)<inf>2</inf>·2H<inf>2</inf>O and [Zn(dmpy)<inf>2</inf>](sac)<inf>2</inf>·2H<inf>2</inf>O complexes were determined by single X-ray diffraction. The crystals are isostructural with the triclinic crystal system (P1) and both the Ni(II) and Zn(II) ions have distorted octahedral coordination by two dmpy ligands in a meridional configuration. Both crystal structures are stabilized by hydrogen bonds and aromatic π-π stacking interactions forming a three-dimensional network.