A comparative structural and property investigation of four new bivalent transition metal complexes based on 4-nitrophenylacetic acid with rigid 4-nitrobenzoate analogues

Abstract

The synthesis, spectral, thermal, magnetic properties, and structural features of four new one-dimensional (1-D) polymers having formula [M(4-npa)2(μ2-H2O)(H2O)2]·2H2O where (M=Mn 1; M=Co 2; M=Zn 3; M=Ni 4; 4-npa=4-nitrophenylacetate) are investigated and compared with corresponding 4-nitrobenzoate (4-nba) analogues. The single crystal studies reveal that compounds 1–3 are isostructural and crystallize in the centrosymmetric monoclinic space group P21/c. Their structure consists of distorted octahedra of a unique central metal ion, two crystallographically unique monodentate 4-npa ligands, two terminal water molecules, a μ2-bridging bidentate water and two lattice water molecules. The central metal exhibits a distorted {MO6} octahedron with two O atoms from terminal water molecules disposed cis to each other, two O atoms from the monodentate carboxylates also disposed in a cis geometry and the remaining two O atom from the μ2-bridging bidentate water disposed trans. The μ2-brindging mode of water leads to the formation of an extended 1-D chain structure. The lattice water links parallel 1-D chains with the aid of H-bonding interactions. The IR, XRD powder pattern, thermal characterization and elemental analysis reveal that the structure of polycrystalline compound 4 is nearly identical with that of other 4-npa analogues.