Dimerized p-Semiquinone Radical Anions Stabilized by a Pair of Rare-Earth Metal Ions

Abstract

Here we report stable p-quinone-radical-bridged rare-earth complexes involving the ligand tetramethylquinone (QMe(4)(center dot-)). The complexes, {Y[QMe(4))Cl-center dot-(2). (THF)(3)]}(2) (1) and {Gd[QMe(4))Cl-center dot-(2)(THF)(3)]}(2) (2), where THF = tetrahydrofuran, are sufficiently stable that we can measure the single-crystal structures and perform magnetic and electron paramagnetic resonance measurements. These studies show the presence of a semiquinone form and that the magnetic interaction between the radicals in the dimer is strong and antiferromagnetic.