The chameleon-like coordinating ability of 2,3-di(pyridyl)pyrazine-type ligands

This survey is dedicated to the multifaceted modes of binding of metal ions by polyazine N donors like 2,3-di(2-pyridyl)pyrazine (dpp), 5,6-di(2-pyridyl)quinoxaline (dpq) and 9,10-di(2-pyridyl)benzoquinoxaline (dpbq) and related substituted analogs, covered until the end of 2016. These compounds display the potential coordination of the dipyridinopyrazine block consisting of two pyridine and two pyrazine N donor atoms. This report illustrates the structural features of the mono-, di- and multinuclear complexes, whenever crystallographic information was available. In the absence of X-ray work, as is the case for tri-, tetra-, and multinuclear systems, the overall organization of the complex systems is that proposed by the authors. Synthetic procedures, physicochemical properties, especially UV–visible spectroscopic and electrochemical behaviour, are given some attention. © 2017 Elsevier B.V