Sodium naphthalenide reduction of 1,3 –diphenyl–6–(tert-butyl) fulvene: Stabilizing Eu2+ with a sterically demanding ansa–ligand framework

Publication date: Available online 12 December 2017 Source:Journal of Organometallic Chemistry Author(s): Sonya K. Adas, Gary J. Balaich Stereoselective syntheses of three new rac di–(tert–butyl)ethano bridged metallocene compounds of Yb, Eu and Sm were carried out by a unique strategy involving hydrocarbon radical anion coupling of a trisubstituted pentafulvene followed by incorporation of the metal by K+ salt metathesis reactions. Reductive coupling of 1,3–diphenyl–6–(tert-butyl) fulvene with sodium naphthalenide gave the corresponding bis(cyclopentadiene) ansa–ligand precursor rac–[(CHBut)2(Ph2C5H3)2] HL. Subsequent reaction of HL with KN(SiMe3)2 afforded the corresponding di–potassium salt complex [(CHBut)2(Ph2C5H2)2]K2(THF)3 1. Reactions of 1 with LnI2 (Ln = Yb, Eu, Sm) afforded new lanthanide ansa–metallocenes, [(CHBut)2(Ph2C5H2)]2Yb(DME) 2, [(CHBut)2(Ph2C5H2)]2Eu(DME)2 3 and [(CHBut)2(Ph2C5H2)]2Sm(DME)2 4 in good yields. The ansa–europocene 3 is the first example of a Eu2+ ion complexed by an ethano–bridged cyclopentadienyl ligand. This work underscores the usefulness of hydrocarbon radical anion coupling in the construction of sterically demanding Ph2Cp based ansa–ligand frameworks for d- and f-block metallocenes.
Source: Journal of Organometallic Chemistry - Category: Chemistry Source Type: research