Octahedral terbium(III) cationic bis(alkoxide) complexes: synthesis, structural features and luminescence

Four new terbium(III) cationic complexes containing two fluorinated alkoxide ligands, [Tb(OCR¹R²R^F)₂(THF)₄][BPh₄] (R¹ = H, R² = R^F = C₆F₅; R¹ = R² = Ph, R^F = CF₂Cl; R¹ = Me, R² = Ph, R^F = CF₃; R¹ = R² = Me, R^F = C₆F₅), were synthesized by protonolysis of Tb–C bonds in cationic organoterbium complex [o-(Me₂NC₆H₄CH₂)₂Tb][BPh₄] with the corresponding alcohols R¹R²R^FC(OH). The complexes obtained exist as separated ion pairs in which the cationic fragments adopt an octahedral configuration featuring cis-arrangement of the alkoxy groups regardless of their steric demand. The complexes display green luminescence at room temperature which shifts toward the blue region upon cooling to 77 K.