Electrochemically Driven Swinging of a Nitrobenzyl Pendant Arm in a Nickel Scorpionand Complex

A radical anion −NO(2) (.−) is formed upon an electrochemically reversible one‐electron reduction of the square‐planar Ni(II) complex of N‐nitrobenzylcyclam. The −NO(2) (.−) group goes to occupy an axial position of the metal ion, thus establishing a significant electronic interaction with the metal center. In particular, the ESR spectrum supports the occurrence of an electron transfer from −NO(2) (.−) to the metal, which therefore presents a significant Ni(I) character. On re‐oxidation, the nitrobenzyl side chain detaches and the Ni(II) complex is restored, providing an example of a fully reversible redox driven intramolecular motion.