Synthesis and Multiple Subsequent Reactivity of Anionic cyclo‐E(3) Ligand Complexes (E=P, As)

A synthetic pathway for the synthesis of novel anionic sandwich complexes with a cyclo‐E(3) (E=P, As) ligand as an end deck was developed giving [Cp′′′Co(η(3)‐E(3))](−) (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 R(2)PCl (R=Ph, Cy, (t)Bu), neutral complexes with a disubstituted cyclo‐E(3)P (E=P, As) ligand in [Cp′′′Co(η(3)‐E(3)PR(2))] (E=P (7 a–c), As (9 a–c)) were obtained. These compounds can be partially or completely converted into complexes with a cyclo‐E(3) (E=P, As) ligand with an exocyclic {PR(2)} unit in [Cp′′′Co(η(2):η(1)‐E(3)PR(2))] (E=P (8 a–c), As (10 a–c)). Additionally, the insertion of the chlorosilylene [LSiCl] (L=((t)BuN)(2)CPh) into the cyclo‐E(3) ligand of [5] and [6] was achieved and the novel heteroatomic complexes [Cp′′′Co(η(3)‐E(3)SiL)] (E=P (11), As (12)) could be isolated. The reaction pathway was elucidated by DFT calculations.