Chemical Properties
Orange to dark red solution
Uses
Used as reagent of low basicity and acidity, useful for the methylenation of carbonyl compounds;
methylenates highly enolizable ketones, esters and lactones, including aldonolactones and acid-labile substrates;
homologs of the reagent perform carbonyl alkylidenations;
reacts with alkynes and nitriles and can initiate the ring-opening metathesis polymerization of strained cyclic alkenes;
Bis(cyclopentadienyl)dimethyltitanium is a useful precursor for Ziegler-Natta polymerization catalysts, a cocatalyst for alkene metathesis and a catalyst for alkene hydrogenation and the dehydrogenative coupling of silanes.
Preparation
Bis(cyclopentadienyl)dimethyltitanium is prepared by a solution of Methyllithium (2.1 equiv) in Et2O is added dropwise to a suspension of Dichlorobis(cyclopentadienyl)titanium in Et2O (3-5 mL mmol-1) cooled in an ice bath. After 1 h the reaction mixture is quenched with ice water, the ether layer is separated, dried over MgSO4, filtered and evaporated. The resulting bright orange crystals of the reagent, obtained in 95% yield, are dissolved in THF or toluene and stored in the dark, in the refrigerator or freezer.
storage
Sensitive to oxygen and light, but can be briefly exposed to air and water. In the solid state the reagent is not stable for more than a few hours at rt, but it can be stored for months in the dark as a THF or toluene solution. Although it is stable in solution at rt, the reagent is best stored in a refrigerator.
