Preparation and Reactivity of Peralkylated Tantalocene Sulfur Complexes Having a Fulvenoid Substructure

The equilibrium mixture of Cp*(η 6 -C 5 Me 4 CH 2 )TaH 2 and [Cp* 2 TaH] reacts with elemental sulfur to give Cp* 2 Ta(η 2 -S 2 )H ( 1 ) and Cp*(η 6 -C 5 Me 4 CH 2 )Ta(η 2 -S 2 ) ( 2 ). Irradiation of 2 by sunlight in the presence of sulfur results in sulfur insertion into the Ta−methylene bond to give Cp*(η 6 -C 5 Me 4 CH 2 S)Ta(η 2 -S 2 ) ( 4 ). The same reaction in the absence of sulfur produces Cp*(η 6 -C 5 Me 4 CH 2 S)Ta( S) ( 5 ), in which the Ta(η 2 -S 2 ) group is transformed into a Ta S moiety accompanied by a migratory sulfur insertion into a Ta−C bond. As a byproduct in these reactions, Cp* 2 Ta( S)SH ( 3 ), which is an isomerization product of the always present 1, is formed. These reactions provide a new insight into the sulfur chemistry of metallocenes having a fulvenoid substructure. All products are characterized by means of IR-, 1 H-, and 13 C-NMR spectra.