Spin density delocalization from a stable free-radical ligand onto diamagnetic metal ions

Abstract

The novel air-stable, free-radical di-imine ligand 4,4,5,5-tetramethyl-2-(2-pyridyl)-Δ²–imidazoline-1-oxyl forms stable 1 : 1 complexes with bivalent, Zn, Cd, and Hg; upon complexation, e.s.r. ligand hyperfine couplings increase from 4·25 G to 5·2 G for the co-ordinating imine nitrogen, decrease from 9·25 G to 7·6 G for the nitroxide nitrogen, and metal hyperfine splitting of 9·6 G and 46 G is observed due to I=½ isotopes of Cd and Hg, respectively.