Lanthanocene Chemistry with [CpR]-, [Cpt]-, [Cptt]-, and [CpR‘2SiMe2]2- Ligands: Synthesis and Characterization of Bis(cyclopentadienyl)lanthanide(III) Halides and Bis(cyclopentadienyl)lanthanide(II) Complexes and Crystal Structures of [{NdCpR2(μ-Cl)}2], [{TmCptt2(μ-I)}2], and [Yb(CpR‘2SiMe2)(THF)2] (CpR = η5-C5H4{CH(SiMe3)2}, Cpt = η5-C5H4(SiMe2But), Cptt = η5-C5H3(SiMe2But)2-1,3, and CpR‘ = η5-C5H3{CH(SiMe3)2}-3)

The bis(substituted cyclopentadienyl)lanthanide(III) halides [{LnCpR2(μ-Cl)}2] (Ln = Pr, Nd, Sm, Dy, Tb, Y), [{LnCptt2(μ-X)}2] (X = Cl, Ln = La, Nd; X = I, Ln = Tm), and [Nd(CpR‘2SiMe2)(μ-Cl)}2] and bis(substituted cyclopentadienyl)lanthanide(II) complexes [LnCpR2(THF)2] (Ln = Sm, Eu, Yb), [YbCpt2(THF)2], [LnCptt2(THF)2] (Ln = Sm, Yb), LnCpR2 (Ln = Sm, Eu, Yb), YbCpt2, LnCptt2 (Ln = Sm, Yb), and [Yb(CpR‘2SiMe2)(THF)2] (CpR = η5-C5H4{CH(SiMe3)2}, Cpt = η5-C5H4(SiMe2But), Cptt = η5-C5H3(SiMe2But)2-1,3 and CpR‘ = η5-C5H3{CH(SiMe3)2}-3) have been synthesized from the appropriate LnCl3, TmI3, or LnI2 with the selected sodium or potassium cyclopentadienide. The complexes were characterized by 1H, 13C, 29Si, and 171Yb (for Yb(II) complexes) NMR spectroscopy, elemental analysis, and mass spectrometry. The molecular structures of [{NdCpR2(μ-Cl)}2], [{TmCptt2(μ-I)}2], and [Yb(CpR‘2SiMe2)(THF)2] have been determined by single-crystal X-ray diffraction studies. Attempts to reduce the complexes [{NdCpR2(μ-Cl)}2], [{Nd...