Formation of Binuclear Zigzag Hexapentaene Titanium Complexes via a Titanacumulene [Ti=C=C=CH 2 ] Intermediate

The reaction of bis(η 5 :η 1 ‐pentafulvene)titanium complexes with an allylidenephosphorylide Ph 3 P=C(H)‐ C(H)=CH 2 leads to binuclear zigzag hexapentaene titanium complexes ( Ti2a , Ti2b ). The formation of the central C 6 H 4 unit can be described as a spontaneous double C−H bond activation process, leading to an R 3 P=C=C=CH 2 intermediate, as a synthon for a titanabutatriene fragment [(Cp R ) 2 Ti=C=C=CH 2 ] (R: 2‐adamantyl, CH(p‐tol) 2 ). In a subsequent dimerization Ti2a and Ti2b are formed, proofed by single‐crystal X‐ray diffraction and NMR measurements. The reaction sequence is confirmed by DFT calculations.