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

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The use of [Cp′′2Zr(η1:1‐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 [CpRNiBr]2 (CpR=CpBn (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 En unit, a degradation as well as aggregation can be observed. Thus, the prismane derivatives [(Cp′′′Ni)2(μ,η3:3‐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 [(CpRNi)3{Ni(μ‐Br)}(μ3‐E)4]2 (CpR=Cp′′′: 6 a (E=P), 6 b (E=As), CpR=CpBn: 8 a (E=P), 8 b (E=As)) can be isolated. Here, a stepwise transfer of En units is possible, with a cyclo‐E4 2− ligand being introduced and unprecedented triple‐decker compounds of the type [{(CpRNi)3Ni(μ3‐E)4}2(μ,η4:4‐E′4)] (CpR=CpBn, Cp′′′; E/E′=P, As) are obtained.