Synthesis, spectroscopic properties and crystal structures of [ML₂Cl₂][M = Th or U; L =η-C₅H₃(SiMe₃)₂-1,3] and [UL₂X₂](X = Br, I or BH₄)

Abstract

1,3-Bis(trimethylsilyl) cyclopentadienyl has been employed in the preparation of some actinocene(IV) halides and tetrahydridoborates. Crystal structure determinations of [M{C5H3(SiMe3)2-1,3}2Cl2](M = Th or U) and [U{C5H3(SiMe3)2-1,3}2X2](X = Br or BH4) showed that these four complexes are isostructural, crystallising in the space group C2/c. The iodo derivative [U{C5H3-(SiMe3)2-1,3}2I2] crystallises in the chiral space group P212121 in which the two cyclopentadienyl groups within the molecule are crystallographically distinct, Variable-temperature 1H and 11B NMR spectroscopic data for [U{C5H3(SiMe3)2-1,3}2(BH4)2] and its thorium analogue revealed the presence of fluxional processes.