A Very Stable Nickel Broken‐Chain Complex with Isolated Ni–Ni Interactions

Two defective nickel-extended metal-atom chain (EMAC) complexes were synthesized from a pyrazine- and naphthyridine-containing ligand and structurally characterized. The chains consist of dinickel and trinickel units with one absent metal center, in spite of which the complexes are very stable. The magnetic interaction between the two terminal, high-spin nickel atoms is very weak with a spin exchange of J = –0.62(3) cm–1. An electrochemical study on one of the defective nickel EMAC complexes showed high resistance to both oxidation and reduction, with one reduction at E1/2 = –0.76 V and no observable oxidation events in the range from –0.9 V to +1.20 V.