Different Inertness of Titanocene [Cp 2 Ti] and Decamethyltitanocene [Cp* 2 Ti] in Reactions with N , N ‐Bis(trimethylsilyl)sulfurdiimide – Elimination of Tetramethylfulvene and Formation of Half‐Titanocene Complexes

The reaction of the titanocene alkyne complex [Cp* 2 Ti(η 2 ‐Me 3 SiC 2 SiMe 3 )] ( 1 ) (Cp* = η 5 ‐pentamethylcyclopentadienyl) with N , N ‐bis(trimethylsilyl)sulfurdiimide ( 2 ) results in the formation of 1,2,3,4‐tetramethylfulvene ( 3 ) as well as three titanium complexes 4 , 5 and 6 . During the reaction, formal elimination of one Cp* ligand induces a series of C–H and N–S bond activation steps, thus yielding the products. The molecular structures of complex 5 and of the free fulvene were determined by X‐ray crystallographic analysis. Evidently, in these reactions [Cp* 2 Ti] is less stable than [Cp 2 Ti]; a possible reason was found to be the well‐known intramolecular C–H activation yielding the tautomeric tetramethylfulvene hydride species, from which 1,2,3,4‐tetramethylfulvene ( 3 ) can dissociate.