Use of the bis(trimethylsilyl)cyclopentadienyl ligand for stabilising early (f0–f3) lanthanocene chlorides; X-ray structure of [(Pr{η-[C5H3(SiMe3)2]}2Cl)2] and of isoleptic scandium and ytterbium complexes

Abstract

Reaction of the appropriate MCl₃ and 2Li-[C₅H₃(SiMe₃)₂] in tetrahydrofuran affords [M{η-[C₅H₃-(SiMe₃)₂]}₂Cl)₂](M = Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu); the X-ray structure of the first early lanthanocene chloride [(Pr{η-[C₅H₃-(SiMe₃)₂]}₂Cl)₂](the Sc and Yb complexes are isostructural) shows the Pr atoms to be in a distorted tetrahedral environment, and important molecular parameters include Pr–Cl_av.. 2·81, Pr–C(η-)_av. 2·76 Å, Pr … Pr′ 4·372(1)Å, Cl–Pr–Cl′ 78, and Pr–Cl–Pr′ 102 °.