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