Synthesis and Reactivity of Anionic Cyclo-E3 (E = P, As) Ligand Complexes.

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( I· 3 -E 3 )] - (Cp''' = 1,2,4-tri-tert-butyl-cyclopentadienyl, 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( I· 3 -E 3 PR 2 )] (E = P ( 7a - c ), As ( 9a - 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( I· 2 :I· 1 -E 3 PR 2 )] (E = P ( 8a - c ), As ( 10a - 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( I· 3 -E 3 SiL)] (E = P ( 11 ), As ( 12 )) could be isolated. The reaction pathway was elucidated by DFT calculations.