Science of Synthesis

Mikami, K.; Matsumoto, Y.; Shiono, T., Science of Synthesis, (2003) 2, 465.

The bis(η5-cyclopentadienyl)titanium(IV) group (including the substituted-cyclopentadienyl analogues) is particularly important in organotitanium chemistry. Bis(η5-cyclopentadienyl)dihalotitanium(IV) complexes were among the first organotitanium compounds to be isolated. Wilkinson and co-workers prepared the first member of this series, dibromobis(η5-cyclopentadienyl)titanium(IV), in 1953. Bis(η5-cyclopentadienyl)titanium complexes are prepared from dichlorobis(η5-cyclopentadienyl)titanium(IV) derivatives. The syntheses of dichlorobis(η5-cyclopentadienyl)titanium(IV) (‌78‌) and its analogues are based on the reactions of lithium, sodium, potassium, or thallium cyclopentadienides with either titanium(IV) chloride or titanium(III) chloride, followed by oxidation in the presence of hydrochloric acid; titanium(IV) chloride–bis(tetrahydrofuran) and titanium(III) chloride–tris(tetrahydrofuran) adducts are also employed. The reaction with titanium(III) halides is preferred with bulky cyclopentadienyl ligands. Steric demand limits the bis(η5-cyclopentadienyl)titanium complexes that can be prepared. Bis(η5-cyclopentadienyl)titani­um(III) complexes are available by reduction of dichlorobis(η5-cyclopentadienyl)titani­um(IV) complexes and reaction of titanium(III) chloride with metal cyclopentadienides. Bis(η5-cyclopentadienyl)titanium(III) complexes polymerize, form solvates, or coordinate ligands into the fourth position, to form a distorted tetrahedral environment around the titanium atom.

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References

Meeeeee Meeeeeeeeee

• 8.Meeeee-Meee, (8888) M 88-8, 888.