Mononuclear, dinuclear and polymeric cobalt(II) complexes built on 4-aryl-2,6-bis(2′-pyrazinyl)pyridines

• Published in: Polyhedron 2017-08, Vol.132, p.64-69
• Main Authors: Li, Li, Liu, E, Xiong, Hangxing, Chan, Corinna, Manke, David R., Golen, James A., Zhang, Guoqi
• Format: Article
• Language: English
• Subjects: 2,6-Bis(2′-pyrazinyl)pyridine; Cobalt(II); Coordination polymer; Crystal structure; Multidentate ligand
• ISSN: 0277-5387
• DOI: 10.1016/j.poly.2017.05.002

New 2,6-bis(2′-pyrazinyl)pyridine derivatives have been synthesized and utilized for the metal-mediated coordination self-assembly with Co(NCS)2. Diverse coordination structures including mononuclear, dinuclear complexes and one-dimensional helical coordination polymer have been revealed, dependent upon the various ligands that were used. [Display omitted] Two new multidentate nitrogen ligands containing a 2,6-bis(2′-pyrazinyl)pyridine (bpp) backbone were synthesized and characterized. The facile Kröhnke condensation procedure allows for efficient synthesis and modification of this class of N-rich ligands. The metal-mediated self-assembly of these ligands along with a previously known derivative with Co(NCS)2 was studied. X-ray structural analysis of the metal assemblies reveals that mononuclear, dinuclear and polymeric structures could be obtained based on the ligands used. Although in most cases including the previously reported results the coordination chemistry of bpp-based ligands involves only inner N3 cavity, with the outer-N donors remaining uncoordinated, the introduction of a 3-pyridyl group to the 4-position of central pyridine of bpp is found to be critical for the synthesis of new coordination polymers. The thermal properties of these metal complexes have been studied.