Synthesis, spectral and structural characterization of three zinc(II) azide complexes with aminopyrazine

Abstract

The reaction between zinc(II) azide, Zn(N 3) 2 and aminopyrazine (ampyz) afforded the complexes: [Zn(N 3) 2(ampyz) 2] ( 1), [Zn(N 3) 2(ampyz)] n ( 2) and [Zn 3(N 3) 6(ampyz) 2] n ( 3). These complexes are characterized by spectroscopic and crystallographic methods. The IR spectra of these compounds are measured and discussed. The structure of 1 consists of isolated tetrahedral zinc atom surrounded by two mono-dentate N-ampyz and two terminal azido ligands. Complex 2 features a zigzag chain of zinc centers in which each zinc is surrounded by alternate di-EO (end-on) and di-EE (end-to-end) azide bridges, the chain thus contains alternate four-membered Zn 2N 2 and eight-membered Zn 2(NNN) 2 rings. The two ampyz ligands are located in cis-arrangement and each of them further binds another zinc atom giving rise to a 3D network. Complex 3 contains two structurally different zinc atoms; the six-coordinate Zn(1) center links two di-EO azido bridges and two trans ampyz, thus having ZnN 6 chromophore. The five-coordinate Zn(2) center binds two di-EO bridging azido groups and the fifth position is occupied by an N atom from a bridging ampyz molecule. Both zinc centers, therefore participate in the formation of a 1D chain of cyclic Zn 2N 2 units. Each ampyz ligand binds another zinc atom via the second pyrazinic N atom giving another cross-chain and thus the structure consists of 2D sheets. In these three complexes the azido ligands of all types are asymmetric and linear within the experimental error.