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

A radical anion −NO2.− is formed upon an electrochemically reversible one‐electron reduction of the square‐planar NiII complex of N‐nitrobenzylcyclam. The −NO2.− 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 −NO2.− to the metal, which therefore presents a significant NiI character. On re‐oxidation, the nitrobenzyl side chain detaches and the NiII complex is restored, providing an example of a fully reversible redox driven intramolecular motion. [ABSTRACT FROM AUTHOR]