Synthesis, X-ray structure and anti-corrosion activity of two silver(I) pyrazino complexes

Journal article, 2009

Two new silver(I) pyrazine complexes [Ag2(ampyz)(NO3)2]n, 1 and {[Ag(2,3-pyzdic)](NO3)}n, 2 (where ampyz = aminopyrazine, and 2,3-pyzdic = 2,3-pyrazinedicarboxamide) were synthesized and structurally characterized by X-ray single crystal structure analysis. Complex 1 has a 2D sheet structure through both bridging μO,O′-(NO3) groups and μN,N′-pyrazine moieties. A 3D structure with a characteristic (10,3)-d or 103-utp net is formed through extensive hydrogen bonding. Complex 2 has a 1D chain structure through bridging μN,N′-pyrazine moieties. Strong hydrogen bonds further connect these chains to extend the dimensionality to a 3D network structure. The complexes were tested as corrosion inhibitors for mild steel in 0.1 M nitric acid medium using potentiodynamic polarization technique. Both complexes are of mixed type corrosion inhibitors with dominant anodic effect. The inhibition efficiencies are 68% and 50% for complexes 1 and 2, respectively. The inhibition mechanisms of both inhibitors are mainly due to adsorption of the inhibitor molecules on the surface of mild steel. All data were compared and fitted to the kinetic-thermodynamic model. The binding constants K are 3263 and 1147 for complexes 1 and 2, respectively.