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

The complex formation of the redox-active ligand bis(N, N'-2,6-diisopropylphenyl)-9,10-phenanthrenediimine ((PDI)-P-Dipp) with alkaline metal (Li, K) and lanthanide (Sm, Dy) cations is studied. The reduction of (PDI)-P-Dipp with an alkaline metal excess affords the dianionic form of the ligand ((Dipp)PDA(2-)), which crystallizes with the potassium cation as the coordination polymer [K-2((Dipp)PDA)(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 ((PSI center dot-)-P-Dipp) crystallized as [Li((PSI)-P-Dipp)(Thf)(2)]. The samarium(III) complex [SmCp*((Dipp)PDA)(.hf)] ( I) is formed by the reduction of (PDI)-P-Dipp with samarocene [SmCp2*(Thf)(2)] (Cp* is pentamethylcyclopentadienide): both the samarium(II) cation and Cp*(-) anion are oxidized in the reaction. (PDI)-P-Dipp 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 (Dipp)PDA(2-) dianion. Similar complexes [Dy((Dipp)PDA)I(Thf)(2)] (IIThf) and [Dy((Dipp)PDA)I(Thf)(Et2O)] (H-Et2O) 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 pi system of the conjugated fragment of the NCCN ligand is observed in IIThf, whereas in IIEt2O this coordination is absent. The reaction with Li-2((Dipp)PDA) affords the binary complex salt [Li(Thf)(3)(Et2O)][DyI2((Dipp)PDA)(Thf)] (III, crystallization from a THF-Et2O mixture). The crystallization from THF gives the [Li(Thf)(4)][DyI2((Dipp)PDA)(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).