Syntheses, Crystal Structure, and Magnetic Properties of a Self‐Assembling Dinickel(II) Helicate with Novel Bipyridine Ligand

A novel polydentate ligand, L = 2,2′‐bipyridyl‐6,6′‐bis(2‐acetylpyrazinohydrazone), was synthesized by condensation of 6,6′‐dihydrazine‐2,2′‐bipyridine and 2‐acetylpyrazine. Reaction of L ligand strands with nickel (II) perchlorate in CH 3 CN generates a double helical dinuclear complex. Its complexation behavior was studied by UV‐Vis spectrophotometric titration experiments that revealed the formation of dinuclear complexes [Ni 2 L 2 ](ClO 4 ) 4 . Moreover, the double‐helical structure of [Ni 2 L 2 ](ClO 4 ) 4 was confirmed by X‐ray diffractometer. Each nickel(II) center occupies a distorted octahedral environment. Variable‐temperature magnetic measurements revealed weak antiferromagnetic interactions between Ni(II) ion centers with J = −0.34 cm −1 .