Reactivity of [Cp₂Zr(^1:1-E₄)] (E=P, As) towards Nucleophiles

The functionalization of the polypnictogen ligand complexes [Cp '' Zr-2(eta(1:1)-E-4)] (E=P (1 a), As (1 b); Cp ''=1,3-di-tertbutyl-cyclopentadienyl) is focused to modify the features of the polypnictogen unit to explore new synthetic pathways for further transformations. The reaction behavior of 1 towards main group nucleophiles is investigated. The reaction of 1 a with (BuLi)-Bu-t leads to the ionic product Li[Cp '' Zr-2(eta(1:1)-(P4Bu)-Bu-t)] (2) where an organic group is attached to a bridgehead phosphorus atom of the butterfly unit. Further reactions of 2 with quenching electrophilic reagents enable the introduction of other substituents. Moreover, a condensation of 2 to [(Cp '' Zr-2)(2)(mu,eta(1:1:1:1)-(P8Bu2)-Bu-t)] (3), containing a novel P-8-unit, has been observed. The reaction of 1 with LiNMe2 and LiCH2SiMe3 leads to a partial fragmentation of the E-4 unit and the compounds [Cp '' Zr-2(eta(2)-E(3)Nu)] (Nu=NMe2: E=P (6 a), As (6 b); Nu=CH2SiMe3: E=P (7 a), As (7 b)) are formed.