Synthesis and characterisation of (η5-cyclopentadienyl)(η5-ring)titanium alkyl (ring = indenyl or C5H4But) complexes. Crystal and molecular structure of racemic [Ti(η5-C5H5)(η5-C9H7)(CH2SiMe3)Cl]

Abstract

New, selective and high-yielding preparations of the mixed-ring complexes [Ti(η⁵-C₅H₅)(η⁵-C₉H₇)C₂] and [Ti(η⁵-C₅H₅)(η⁵-C₅H₄Bu^t)Cl₂] are reported. These have been used to prepare a range of mono- and di-substituted titanium(IV) alkyl and benzenethiolate complexes of the form [Ti(η⁵-C₅H₅)(η⁵-ring)(CH₂SiMe₃)Cl] and [Ti(η⁵-C₅H₅)(η⁵-ring)R₂](ring = indenyl or C₅H₄Bu^t; R = Me, CH₂Ph, CH₂SiMe₃ or SPh). While the indenyl ligand in the racemic, chiral-at-metal complex [Ti(η⁵-C₅H₅)(η⁵-C₉H₇)(CH₂SiMe₃)Cl] is bound in an η⁵ fashion, X-ray structural data clearly indicate that there is some ‘η³ ring-slip’ character to the bonding. The NMR and nuclear Overhauser effect experiments conducted on [Ti(η⁵-C₅H₅)(η⁵-C₅H₄Bu^t)(CH₂SiMe₃)Cl] demonstrate hindered rotation around the Ti–C₅H₄Bu^t bond and show the geometry to be fixed such that the Bu^t and SiMe₃ groups are remote.