Synthesis and structural features of [(C5H4CMe2NMe2)2TiCl], a bis(cyclopentadienyl)Ti(III) complex with internal dimethylamino coordination

Treatment of 6-dimethylamino-6-methylfulvene (1) with methyllithium gave the [C5H4CMe2NMe2]Li product (2) that was characterized by X-ray diffraction. Compound 2 features an oligomeric chain structure with the [C5H4CMe2NMe2] unit serving as a bridging ligand using its Cp anion moiety and the NMe2 donor functionality. Treatment of 2 with FeCl2 yielded the substituted ferrocene 3. The corresponding reaction of 2 with TiCl4(THF)2 gave the titanocene complex (C5H4CMe2NMe2)2TiCl2 (4) that exhibits an ordinary bent metallocene structure in the solid state without involvement of the pendant CMe2NMe2 donor ligands. In contrast, the titanium(III) complex (C5H4CMe2NMe2)2TiCl (5), obtained from the reaction of 2 with TiCl3(THF)3, has one of the two nitrogen donors strongly coordinated to the metal center. In the crystal, complex 5 thus attains a typical pseudotetrahedral Group 4 bent metallocene structure, as shown by an X-ray crystal structure analysis.