A simple synthesis of tetraethynylethenes and representative molecular structures of some dicobalt derivatives

Palladium–copper catalysed cross-coupling reactions of tetracholoroethene with terminal acetylenes RCCH (R=SiMe3, C6H5, C6H4CN-4) in refluxing triethylamine afford the corresponding tetraethynylethenes in 30–60% isolated yields. The reaction of 1,6-bis(trimethylsilyl)-3,4-bis(trimethylsilylethynyl)-hex-3-ene-1,5-diyne with [Co2(CO)6(L2)] [L2=(CO)2 or μ-dppm] affords complexes in which one or two (trans) acetylene moieties are coordinated by a dicobalt fragment.