Oxidative Trimerisierung von Alkinylgruppen an Trimethylphosphan‐Palladium‐Komplexen

Oxidative Trimerization of Alkynyl Groups at Trimethylphosphane Palladium Complexes Alkynylpalladium halides trans‐PdX (C ≡ CR)(PMe3)2 [1, 2, 4, X = Cl, R = SiMe3, (CH2)2CH3, (CH2)5CH3; 3, X = Br, R = (CH2)2CH3] were synthesized by routine methods, while further examples of the series trans‐PdX (C ≡ CR)(PMe3)2 [5, 7, 8, 10, X = Br, R = SiMe3, CMe3, (CH2)2CH3, Ph; 7, 9, 11, X = I, R = SiMe3, SiPh3, OEt] and trans‐PdX (C ≡ CR)(PPh3)2 (12‐14, X=I, R=SiMe3, CMe3, CH2OH) were obtained by oxidative addition of 1‐halogeno‐1‐alkynes to PdL4 (L=PMe3, PPh3). Just above the melting point or decomposition point 5‐7 are transformed by oxidative trimerization of the alkynyl groups to give enediynyl complexes trans‐PdX[C(C ≡ CR)=C(C ≡ CR)R](PMe3)2 (15, 16, R=SiMe3, X=Br, I; 17, X=Br, R=CMe3). According to an X‐ray structure analysis 17 has E configuration.