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

Three new polymeric zinc(II) azido complexes, namely [Zn(N3)2(3-Brpy)]n (1), [Zn(N3)2(4-Etpy)]n (2) and [Zn2(N3)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(N3)2]n in which each zinc atom is surrounded by double di-end on (EO) bridging azido ligands forming cyclic Zn2N2 units. Furthermore, each zinc atom links a N hetero atom of the pyridine moiety leading to ZnN5 chromophore. The geometry around the zinc center is best described as distorted trigonal bipyramid. Although complex 3 consists of the 1D chain of [Zn(N3)2]n with double di-EO azido bridges around each zinc center with almost planar Zn2N2 cyclic units, the pyrazinic moiety behaves as a bidentate bridging N,N′-ligand that binds the zinc centers across the [Zn2(N3)2]n chains extending the structure to be two-dimensional sheets. The Zn … Zn distances within the Zn2N2 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.