Europium and Ytterbium Complexes with the Redox Active Acenaphthene-1,2-Diimine Ligand

Abstract

The oxidation of [(Dpp-Bian)Eu(Dme)₂] (I) (Dpp-Bian is the 1,2-bis[(2,6-diisopropylphenyl) imino]acenaphthene dianion, Dme = 1,2-dimethoxyethane), prepared in situ, with 0.5 mol equiv. of iodine in Thf gives europium(II) dimer, [(Dpp-Bian)Eu(μ-I)(Thf)₂]₂ (II) (Thf = tetrahydrofuran), with the Dpp-Bian ligand as radical anion. The exchange reaction of II with potassium dithiocarbamate affords europium( II) dimer, [(Dpp-Bian)Eu[SC(S)NMe₂](Thf)]₂ (III), which also contains the Dpp-Bian radical anion. However, the oxidation of the ytterbium complex [(Dpp-Bian)Yb(Dme)₂] (IV) with 0.5 mol equiv. of [Me₂NC(S)S]₂ gives the monomeric product [(Dpp-Bian)Yb[SC(S)NMe₂](Dme)] (V), in which Dpp-Bian is still the dianion and the ytterbium atom is oxidized to the trivalent state. The reaction of II with potassium thiocyanate gives europium(II) isothiocyanate complex with the radical anion diimine ligand [(Dpp-Bian)Eu(NCS)(Dme)₂] (VI). The molecular structures of complexes II, III, V, and VI were determined by X-ray diffraction (CIF files CCDC 1576687–1576690, respectively).