Synthesis and Multiple Subsequent Reactivity of Anionic cyclo-E₃ Ligand Complexes (E=P, As)

A synthetic pathway for the synthesis of novel anionic sandwich complexes with a cyclo-E₃ (E=P, As) ligand as an end deck was developed giving [Cp'''Co(η³ -E₃ )]^- (Cp'''=1,2,4-tri-tert-butylcyclopentadienyl, E=P ([5]), As ([6])) in good yields suitable for further reactivity studies. In the reaction with the chlorophosphanes R₂ PCl (R=Ph, Cy, ^t Bu), neutral complexes with a disubstituted cyclo-E₃ P (E=P, As) ligand in [Cp'''Co(η³ -E₃ PR₂ )] (E=P (7 a-c), As (9 a-c)) were obtained. These compounds can be partially or completely converted into complexes with a cyclo-E₃ (E=P, As) ligand with an exocyclic {PR₂ } unit in [Cp'''Co(η² :η¹ -E₃ PR₂ )] (E=P (8 a-c), As (10 a-c)). Additionally, the insertion of the chlorosilylene [LSiCl] (L=(^t BuN)₂ CPh) into the cyclo-E₃ ligand of [5] and [6] was achieved and the novel heteroatomic complexes [Cp'''Co(η³ -E₃ SiL)] (E=P (11), As (12)) could be isolated. The reaction pathway was elucidated by DFT calculations.