Lanthanide (Sm, Dy) Complexes with the 9,10-Phenanthrenediimine Redox-Active Ligand: Synthesis and Structures

Abstract

The complex formation of the redox-active ligand bis(N,N'-2,6-diisopropylphenyl)-9,10-phenanthrenediimine (^DippPDI) with alkaline metal (Li, K) and lanthanide (Sm, Dy) cations is studied. The reduction of ^DippPDI with an alkaline metal excess affords the dianionic form of the ligand (^DippPDA^2–), which crystallizes with the potassium cation as the coordination polymer [K₂(^DippPDA)(Thf)₃] (Thf is tetrahydrofuran). The reaction of equimolar amounts of the lithium salt with the dianionic form of the ligand and neutral diimine affords the lithium complex with the radical-anion form (^DippPSI^•–) crystallized as [Li(^DippPSI)(Thf)₂]. The samarium(III) complex [SmCp*(^DippPDA)(Тhf)] (I) is formed by the reduction of ^DippPDI with samarocene [Sm\({\text{Cp}}_{2}^{*}\)(Thf)₂] (Cp* is pentamethylcyclopentadienide): both the samarium(II) cation and Cp*^– anion are oxidized in the reaction. ^DippPDI does not react with similar ytterbocene. The dysprosium(III) complexes are synthesized by the ion exchange reactions between DyI₃(Thf)_3.5 and potassium or lithium salt with the ^DippPDA^2– dianion. Similar complexes [Dy(^DippPDA)I(Thf)₂] (II^Thf) and [Dy(^DippPDA)I(Thf)(Et₂O)] (\({\mathbf{I}}{{{\mathbf{I}}}^{{{\text{E}}{{{\text{t}}}_{{\text{2}}}}{\text{O}}}}}\)) are formed in the reactions with the potassium salt depending on the solvent used: a THF–hexane or a diethyl ether–n-hexane mixture, respectively. The coordination of the dysprosium cation by the π system of the conjugated fragment of the NCCN ligand is observed in II^Thf, whereas in \({\mathbf{I}}{{{\mathbf{I}}}^{{{\text{E}}{{{\text{t}}}_{{\text{2}}}}{\text{O}}}}}\) this coordination is absent. The reaction with Li₂(^DippPDA) affords the binary complex salt [Li(Тhf)₃(Et₂O)][DyI₂(^DippPDA)(Тhf)] (III, crystallization from a THF–Et₂O mixture). The crystallization from THF gives the [Li(Тhf)₄][DyI₂(^DippPDA)(Thf)] salt (III') containing the same anion as III. The structures of all new complexes are studied by X-ray diffraction (XRD, CIF files CCDC nos. 2260307–2260313).