E4 Transfer (E=P,As) to Ni Complexes

The use of Cp′′₂Zr(η^1:1-E₄)] (E=P ( 1 a ), As ( 1 b ), Cp′′=1,3-di-tert-butyl-cyclopentadienyl) as phosphorus or arsenic source, respectively, gives access to novel stable polypnictogen transition metal complexes at ambient temperatures. The reaction of 1 a/1 b with Cp^RNiBr]₂ (Cp^R=Cp^Bn (1,2,3,4,5-pentabenzyl-cyclopentadienyl), Cp′′′ (1,2,4-tri-tert-butyl-cyclopentadienyl)) was studied, to yield novel complexes depending on steric effects and stoichiometric ratios. Besides the transfer of the complete E_n unit, a degradation as well as aggregation can be observed. Thus, the prismane derivatives (Cp′′′Ni)₂(μ,η^3:3-E₄)] ( 2 a (E=P); 2 b (E=As)) or the arsenic containing cubane (Cp′′′Ni)₃(μ₃-As)(As₄)] ( 5 ) are formed. Furthermore, the bromine bridged cubanes of the type (Cp^RNi)₃{Ni(μ-Br)}(μ₃-E)₄]₂ (Cp^R=Cp′′′: 6 a (E=P), 6 b (E=As), Cp^R=Cp^Bn: 8 a (E=P), 8 b (E=As)) can be isolated. Here, a stepwise transfer of E_n units is possible, with a cyclo-E₄^2? ligand being introduced and unprecedented triple-decker compounds of the type {(Cp^RNi)₃Ni(μ₃-E)₄}₂(μ,η^4:4-E′₄)] (Cp^R=Cp^Bn, Cp′′′; E/E′=P, As) are obtained.