Synthesis and structural characterization of three new 1D and 2D zinc(II) azide polymers with some pyridine and pyrazine derivative ligands

Abstract

Three new polymeric zinc(II) azido complexes, namely [Zn(N 3) 2(3-Brpy)] n ( 1), [Zn(N 3) 2(4-Etpy)] n ( 2) and [Zn 2(N 3) 4(2,5-dmpyz)] n ( 3), where Brpy = bromopyridine, Etpy = ethylpyridine and dmpyz = dimethylpyrazine have been prepared and structurally characterized. The IR spectra of these complexes are measured and discussed. The structures of 1 and 2 are similar and feature one-dimensional zigzag chain of [Zn(N 3) 2] n in which each zinc atom is surrounded by double di-end on (EO) bridging azido ligands forming cyclic Zn 2N 2 units. Furthermore, each zinc atom links a N hetero atom of the pyridine moiety leading to ZnN 5 chromophore. The geometry around the zinc center is best described as distorted trigonal bipyramid. Although complex 3 consists of the 1D chain of [Zn(N 3) 2] n with double di-EO azido bridges around each zinc center with almost planar Zn 2N 2 cyclic units, the pyrazinic moiety behaves as a bidentate bridging N, N′-ligand that binds the zinc centers across the [Zn 2(N 3) 2] n chains extending the structure to be two-dimensional sheets. The Zn … Zn distances within the Zn 2N 2 units are similar, fall within the range of 3.20–3.26 Å, and the azido ligands are asymmetric and linear within experimental error in all of these three complexes.