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

Abstract

(dipy)Ni(COD) react with duroquinone (Dch) or anthraquinone (Ach) to yield the complexes (dipy)Ni(η 4 -Dch) or (dipy)Ni(η 4 -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 (Cy 3P) 2Ni(C 2H 4) the complexes (Cy 3P)Ni(η 4-Dch) or (Cy 3P) 2Ni(η 4 -Ach) are obtained, whereas a 1,1-coupling of quinone and the coordinated phosphine proceeds during the reaction between p-benzoquinone of chloranil and (Cy 3P) 2Ni(C 2H 4). By ESR studies it was demonstrated that with Ni(Cy 3P⋯Ch) 2 or Ni(Cy 3P⋯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 (Cy 3P) 2Ni(C 2H 4) and the analogous platinum or palladium complexes, which are substituted by p-benzoquinone while an oxidative addition proceeds with chloranil.