Nickel(ii) complexes of cyclen- and cyclam-pyridine: topological reorganisations induced by electron transfer

Abstract

The Ni^II complexes of cyclen- and cyclam-pyridine (respectively 1-pyridin-2-ylmethyl-1,4,7,10-tetraazacyclododecane and 1-pyridin-2-ylmethyl-1,4,8,11-tetraazacyclotetradecane denoted [Ni^IIL¹]²⁺ and [Ni^IIL²]²⁺) have been isolated and characterised by X-ray diffraction, UV-visible spectroscopy and electrochemical studies for the [Ni^IIL²]²⁺ complex. In particular, the [Ni^IIL²]²⁺ complex adopts two distinct and stable geometries (type I and V), which mainly differ by the macrocycle configuration. In solution, the isomerisation process between these two configurations is driven by the nickel-centered electron transfer.