Coordination of a mesogenic Schiff-base with MnII, CoII, NiII, CuII and ZnII: Synthesis, spectral studies and crystal structures

A novel mesogenic (nematic) Schiff-base, N,N′-di-4-(4′-pentyloxybenzoate)salicylidene diaminoethane, H2dpbsde (abbreviated as H2L5) was synthesized and its structure studied. The Schiff-base crystallizes in the non-centrosymmetric space group Pna21 with Z = 4, and the mesogenic isomorphous nickel and copper complexes, [NiL5]2 and [CuL5], in the centrosymmetric space group P21/c with Z = 4. The (L5)2− species coordinates to the metal ions through two phenolate oxygens and two azomethine nitrogens. Both the [NiL5]2 and [CuL5] complexes involve cis-MN2O2 planes; the former complex has a low-spin distorted square-pyramidal geometry with a Ni–Ni bonding of 3.337 Å and the latter, a square-planar geometry.

Graphical abstractThe mesogenic (nematic) Schiff-base, N,N′-di-4-(4′-pentyloxybenzoate)salicylidene diaminoethane, H2L5, crystallizes in the non-centrosymmetric space group Pna21 with Z = 4, and the mesogenic (nematic) isomorphous nickel and copper complexes, [NiL5]2 and [CuL5], in the centrosymmetric space group P21/c with Z = 4; both the NiII and CuII complexes possess cis-MN2O2 planes with a low-spin distorted square-pyramidal geometry involving Ni–Ni bonding in the former case and a square-planar geometry in the latter one.Figure optionsDownload full-size imageDownload as PowerPoint slide