Ligand redistribution reactions as a route to cyclopentadienyl- or 1-aza-allylzirconium(IV) trichlorides and the x-ray structures of [{ Cl 2(μ-Cl)} 2 and [ 2Cl 2] LL′ = N(R)C(Bu t)CHR, R=SiMe 3

Abstract

Mixing equimolar portions of ZrCl 4 and [Zr(Cp x) 2Cl 2] in toluene at ambient temperature rapidly gave, in a very high yield, a precipitate of ZrCp xCl 3 [ Cp x = C 5 H 5 ( 1), C 5 H 4 Bu t ( 2) or C 5 H 3 Bu 2 t −1,3 ( 3) ]. Addition of tetrahydrofuran (THF) to each of 2 or 3 at ca 20°C caused the bright yellow colour to be discharged and the solid to dissolved, due to the formation of [Zr(Cp x) 2Cl 2] and [ZrCl 4(THF) 2]; this was established by preparative scale experiments and also by 91Zr NMR spectroscopic studies. The 1-aza-allylzirconium(IV) chloride [{ ▪Cl 2(μ-Cl)} 2 ( 4) was obtained by a similar redistribution reaction as 1–3, from rac- ▪ 2Cl 2] ( 5) and ZrCl 4[LL′ = N(R)C(Bu t)CHR, R = SiMe 3]. The X-ray structures of 4 and 5 have been determined.