The syntheses, crystal structures, spectroscopic and thermal characterization of new pyridine-2,5-dicarboxylate compounds

Abstract

In this study, four new M(II)-isocinchomeronic acid (pyridine-2,5-dicarboxylic acid) complexes with ethylenediamine (en) and 2,2′-bipyridine (bipy), namely [Co(en)3][Co(pydc)2(H2O)2]·2H2O (1), [Ni(Hpydc)2(H2O)2] (2), [Cu(en)2(H2O)][Cu3(pydc)4(en)2(H2O)2]·3H2O (3) and [Cu(bipy)3][Cu(pydc)(bipy)2]·2Cl·12H2O (4) (H2pydc=pyridine-2,5-dicarboxylic acid), have been synthesised. Elemental, thermal analyses and IR spectroscopic studies have been carried out in order to characterise the complexes. The molecular structures of the complexes have been determined using single crystal X-ray diffraction. The geometry displayed by the Co(II) (1) and Ni(II) (2) ions is distorted octahedral. The Cu(II) ions display a square pyramidal geometry and distorted octahedral geometry in 3, while each Cu(II) ion exhibits a distorted octahedral geometry in 4. Molecules of each complex are linked into a 3D framework structure by N–H⋯O, O–H⋯O and C–H⋯O hydrogen bonds.