Synthesis and Reactivity of a Cerium(III) Scorpionate Complex Containing a Redox Non-Innocent 2,2′-Bipyridine Ligand

The Ce(III) hydrotris(3,5-dimethylpyrazolyl)borate complex [Ce(Tp^Me2)₂(κ²-dmpz)] (1) (Tp^Me2 = {HB(dmpz)₃}⁻; dmpz = 3,5-dimethylpyrazolide) was isolated in fair yield from the reaction of [Ce(I)₃(THF)₄] with two equivalents of [K(Tp^Me2)] via the facile decomposition of Tp^Me2. [Ce(Tp^Me2)₂(bipy)] (2) was synthesized in poor yield by the “one-pot” reaction of [Ce(I)₃(THF)₄], bipy (bipy = 2,2′-bipyridine), KC₈ and two equivalents of [K(Tp^Me2)] in tetrahydrofuran (THF). The reaction of 2 with N-methylmorpholine-N-oxide produced the known decomposition product [Ce(Tp^Me2)(μ-BOp^Me2)]₂ (3) (BOp^Me2 = {HBO(dmpz)₂}²⁻) in poor yield, presumably by N–O and B–N bond cleavage of a reactive intermediate. The reaction of 2 with trimethylsilylazide gave [Ce(Tp^Me2)₂(N₃)] (4) in poor yield; the fate of bipy and the trimethylsilyl group is unknown. Complexes 1–4 were characterized by single crystal XRD, NMR and FTIR spectroscopy and elemental analysis. Complex 2 was additionally probed by UV/Vis/NIR and Electron Paramagnetic Resonance (EPR) spectroscopies, Cyclic Voltammetry (CV) and magnetometry, which together indicate a formal 4f¹ Ce(III) center coordinated by a bipy·⁻ radical anion in this system. View Full-Text