Titanium and zirconium chloro, oxo and alkyl derivatives containing silyl-cyclopentadienyl ligands. Synthesis and characterisation

Abstract

The reaction of the tetramethylcyclopentadiene-silyl substituted derivative C 5Me 4(SiMe 3)(SiMe 2Cl) with MCl 4 afforded the trichloro mono-tetramethylcyclopentadienyl complexes M(η 5-C 5Me 4SiMe 2Cl)Cl 3 [M=Ti ( 1), Zr ( 2)] with selective elimination of SiMe 3Cl. Compound 1 reacts with deoxygenated water in methylene chloride, with the evolution of HCl, to give the dinuclear titanium compound {Ti[μ-(η 5-C 5Me 4SiMe 2O-κO)]Cl 2} 2 ( 3), which was converted into the μ-oxo complex {Ti[μ-(η 5-C 5Me 4SiMe 2O-κO)]Cl} 2(μ-O) ( 4) by a further hydrolysis reaction which occurred when a solution of 3 in toluene was refluxed for a long period of time in the air. Depending on the size of the alkyl ligand, reactions of the mononuclear compound 1 with an appropriate alkylating reagent rendered the peralkylated Ti(η 5-C 5Me 4SiMe 2R)R 3 [R=Me ( 5), CH 2Ph ( 6)] or partially alkylated {Ti[(η 5-C 5Me 4SiMe 2(CH 2SiMe 3)]Cl(CH 2SiMe 3) 2} ( 7) compounds by a salt metathesis route. Attempts to synthesise a partially methylated or benzylated complex were unsuccessful. Treatment of the dinuclear compound 3 with four equivalents of MgClMe yielded the tetramethyl derivative {Ti[μ-(η 5-C 5Me 4SiMe 2O-κO)]Me 2} 2 ( 8), while the same reaction carried out with MgCl(CH 2Ph) or Mg(CH 2Ph) 2·2THF gave the chloro-benzyl derivative {Ti[μ-(η 5-C 5Me 4SiMe 2O-κO)]Cl(CH 2Ph)} 2 ( 9) as an equimolar mixture of diastereomers, regardless of the molar ratio of the alkylating reagent used. All of the new compounds were characterised by elemental analysis and NMR spectroscopy.