E 4 Transfer (E=P, As) to Ni Complexes

The use of [Cp'' Zr(η -E )] (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 NiBr] (Cp =Cp (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 unit, a degradation as well as aggregation can be observed. Thus, the prismane derivatives [(Cp'''Ni) (μ,η -E )] (2 a (E=P); 2 b (E=As)) or the arsenic containing cubane [(Cp'''Ni) (μ -As)(As )] (5) are formed. Furthermore, the bromine bridged cubanes of the type [(Cp Ni) {Ni(μ-Br)}(μ -E) ] (Cp =Cp''': 6 a (E=P), 6 b (E=As), Cp =Cp : 8 a (E=P), 8 b (E=As)) can be isolated. Here, a stepwise transfer of E units is possible, with a cyclo-E ligand being introduced and unprecedented triple-decker compounds of the type [{(Cp Ni) Ni(μ -E) } (μ,η -E' )] (Cp =Cp , Cp'''; E/E'=P, As) are obtained.