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We wish to report a new type of transformation of a pentamethylcyclopentadienyl group (Cp*) by stepwise hydrogen abstraction into an 3:?;4-1,2,3-trimethyl-4,5-dimethylenecyclopentenyl ligand.

Reactions of CpTiCl 2 (Cp = η 5-C 5 H 5) with RMgX (X = Cl, Br) yield the complexes CpTiR 2 (R = CH 2 Ph, η 3-C 3 H 5). The complex Cp Ti(η 3-C 3 H 5) 2 (Cp = η 5-C 5 Me 5) was prepared analogously from Cp TiCl 2 (THF). CpVCl 2 (PEt 3) 2 and Cp´VCl 2 (PEt 3) 2 (Cp´ = η 5-C 5 H 4 Me) were used for the preparation of CpV(CH 2 Ph) 2 , CpV(η 3-C 3 H 5) 2 , CpV(η 3-1-MeC 3 H 4) 2 and Cp´V(η 3-C 3 H 5) 2 , respectively. The corresponding Cp V derivatives could not be obtained. The reaction of CpCrCl 2 (thf) with C 3 H 5 MgCl gives a dimeric complex [CpCr(C 3 H 5)] 2 , probably via intermediate formation of CpCr(C 3 H 5) 2. CpV-bis-allyl complexes are active in the catalytic isomerization of alkenes; a 1,3-hydride shift via a π-allylmetal hydride species is proposed. In contrast no activity in isomerization was observed for CpTi(C 3 H 5) 2 and Cp Ti(C 3 H 5) 2. CpMX 2 L n + 2 RM´ CpMR 2 L m +(nm)L + 2 M´X (1)

An unusual structure and a unique route of formation characterize the title compound 1. It is formed from the fulvene‐titanium compound [Cp*(C5Me4CH2)Ti] and 2‐methylpyridine in ether. H‐6 of the pyridine derivative migrates to Ti, and the fulvene ligand is transformed by CC bond formation into a functionalized cyclopentadienyl ligand (Cp*=η5Me5).