Titanium indenyldimethylamido complexes: synthesis, characterisation and theoretical calculations. Crystal structure of [Ti(η5-Ind)(NMe2)Cl2]

Abstract

Reactions of Ti(Ind)Cl₃, 1, with LiNMe₂ afforded the corresponding titanium indenyldimethylamido complexes Ti(Ind)(NMe₂)Cl₂, 2, Ti(Ind)(NMe₂)₂Cl, 3, and Ti(Ind)(NMe₂)₃, 4, depending on the reaction conditions. Treatment of 2 and 3 with LiMe yielded Ti(Ind)(NMe₂)Me₂, 5, and Ti(Ind)(NMe₂)₂Me, 6, respectively. Chloride metathesis reactions of Ti(Ind)(NMe₂)₂Cl with Me₃SiCH₂MgCl, LiCCPh and LiCCSiMe₃ gave Ti(Ind)(NMe₂)₂(CH₂SiMe₃), 7, Ti(Ind)(NMe₂)₂(CCPh), 8 and Ti(Ind)(NMe₂)₂(CCSiMe₃), 9. The solid-state molecular structure of 2 was determined. ¹H and ¹³C NMR data and DFT calculations (full geometry optimisations) showed that the indenyl ring remains approximately planar and exhibits an η⁵ co-ordination mode in all the complexes. The amido groups have a preference for binding in the way that favours π bonding to the titanium. Even in the trisamido complex the indenyl remains η⁵, π bonding to the ring being preferred to that from the amides.