Decamethyltitanocene dichloride is an organotitanium compound with the formula Cp*<sub>2</sub>TiCl<sub>2</sub> (where Cp* is C<sub>5</sub>(CH<sub>3</sub>)<sub>5</sub>, derived from pentamethylcyclopentadiene). It is a red solid that is soluble in nonpolar organic solvents. The complex has been the subject of extensive research. It is a precursor to many organotitanium complexes. The complex is related to titanocene dichloride, which lacks the methyl groups.
The complex is prepared by the reaction of titanium tetrachloride with LiCp*. An intermediate in this synthesis is (pentamethylcyclopentadienyl)titanium trichloride.
Reduction of Cp*<sub>2</sub>TiCl<sub>2</sub> in the presence of ethylene gives the adduct Cp*<sub>2</sub>Ti(C<sub>2</sub>H<sub>4</sub>). The analogous Cp compound has not been prepared, a contrast that highlights the advantages of the Cp* ligand. This pentamethylcyclopentadienyl (Cp*) species undergoes many reactions such as cycloadditions of alkynes.
The dicarbonyl complex Cp*<sub>2</sub>Ti(CO)<sub>2</sub> is prepared by reduction of Cp*<sub>2</sub>TiCl<sub>2</sub> in the presence of carbon monoxide.