Supramolecular Structure of an Unsymmetrical Pyrazine‐Modulated Tetrapyridyltriamide and Its Complexes

An unsymmetrical pyrazine‐modulated oligo‐α‐pyridylamine ligand as N 2 ‐(pyrazin‐2‐yl)‐ N 6 ‐(6‐(pyridin‐2‐ylamino)pyridin‐2‐yl)pyridine‐2,6‐diamine (H 3 tpz) and its copper(II) and cobalt(II) complexes have been synthesized and structurally characterized. The free ligand H 3 tpz ( 1 ) exhibits a syn‐anti‐syn‐anti‐syn‐anti conformation, and shows a double chain supramolecular structure through hydrogen bonds and π‐π interactions. H 3 tpz is a quadridentate ligand in both copper and cobalt mononuclear complexes and coordinates to metal atoms in an all‐ anti mode. The copper(II) ion in [Cu(H 3 tpz)(ClO 4 )]‐ClO4 ( 2 ) is five‐coordinated in tetragonal pyramid geometry with one of the perchlorate anions being weakly coordinated at the apex position. The cobalt(II) ion in [Co(H 3 tpz)(CH 3 OH) 2 ](ClO 4 ) 2 ( 3 ) is six‐co‐ordinated in octahedron geometry. Extensive hydrogen bonds are formed, and construct the complexes 2 and 3 into 1D supramolecular structure.