Cyclobutadiene Complexes, XII. Alkynyl‐Substituted Tricarbonyl(cyclobutadiene)iron Complexes: Stille Coupling of Iodocyclobutadiene Complexes with Stannylalkynes

The synthesis of mono‐, di‐, tri‐ and tetraalkynylated tricarbonyl(cyclobutadiene)iron complexes is accomplished by a repetitive metalation/iodination/coupling sequence. Application of this sequence leads to the synthesis of oligomeric cyclobutadiene complexes with various topologies, inter alia to the synthesis of a perethynylated dimer 24 . Alternatively a one‐step coupling procedure (Stille‐Farina) has been used to synthesize tetraalkynylated tricarbonyl(cyclobutadiene)‐irons 26 .