Anionic dichlorolanthanocene compounds. X-ray crystal structures of [{(Me 3Si) 2C 5H 3} 2LnCl 2][Li(THF) 4] (Ln=Er, Yb) and {(Me 3Si) 2C 5H 3} 2Yb(μ-Cl) 2Li(THF) 2

Abstract

Treatment of LnCl 3 with two equivalents of Cp″Li (Cp″=(Me 3Si) 2C 5H 3) in THF gave, after crystallization from a THF– n-hexane solution at −30°C, ionic compounds [Cp″ 2LnCl 2][Li(THF) 4] (Ln=Er ( 1), Yb ( 2)) in good yield. Recrystallization of 2 from a toluene solution afforded an ‘ate’ compound Cp″ 2Yb(μ-Cl) 2Li(THF) 2 ( 3). Interestingly, recrystallization of 3 from a mixed solvent of THF– n-hexane did not give compound 2, and only 3 was isolated, indicating that the dissociation of THF may be an irreversible process or 3 is a thermodynamically more stable compound. All three compounds were fully characterized by various spectroscopic date and single-crystal X-ray analyses. Compounds 1 and 2 are the rare structurally characterized examples of an anionic dichlorolanthanocene stabilized by an alkali metal complex ion.