Reaktionen von Nickel(0)-Komplexen mit p-Chinonen. Bildung phosphinsubstituierter Radikalanionen

(dipy)Ni(COD) react with duroquinone (Dch) or anthraquinone (Ach) to yield the complexes (dipy)Ni(η⁴ -Dch) or (dipy)Ni(η⁴ -Ach). Chloranil (CA), however, reacts as an oxidant and depending on the temperature (dipy)Ni^II(CA^2-) or following an oxidative addition (dipy)Ni^II(Cl)(CAH^-)(THF) are formed.By substitution of (Cy₃P)₂Ni(C₂H₄) the complexes (Cy₃P)Ni(η⁴-Dch) or (Cy₃P)₂Ni(η⁴ -Ach) are obtained, whereas a 1,1-coupling of quinone and the coordinated phosphine proceeds during the reaction between p-benzoquinone of chloranil and (Cy₃P)₂Ni(C₂H₄). By ESR studies it was demonstrated that with Ni(Cy₃P?Ch)₂ or Ni(Cy₃P?CA)₂, resp., complexes are obtained, in which radical anions, which are derived from the product of this 1,1-coupling, are coordinated to low-spin nickel (II). There is a significant difference between (Cy₃P)₂Ni(C₂H₄) and the analogous platinum or palladium complexes, which are substituted by p-benzoquinone while an oxidative addition proceeds with chloranil.