Electrochemical reductive carbon-to-carbon coupling of σ-ethynyl complexes of transition metals

The electrochemical properties of σ-ethynyl complexes of chromium subgroup metals were studied by cyclic voltammetry and preparative-scale electrolysis. The redox cycle of C₅H₅(CO)₃CrC=CPh was shown to give the bis-carbyne complex (η⁵-C₅H₅)(CO)₂Cr≡C-C(Ph)=C(Ph)-C-Cr(CO)₂(η⁵-C₅H₅) formedvia the reductive C_β−C_β coupling of ethynyl moieties. The influence of the nature of the metal atom and the ligand environment on the course of this reaction was considered. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1955–1958, October, 1998.