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.