This thesis describes the synthesis of cyclopentadienyl (Cp) cobalt(I)-complexes of the type [CpCo(I)L1L2]. Systematic variation of the neutral ligands (L) demonstrated that the use of two different ligands – namely an olefin and a phosphite ligand – proved to be superior to the homoleptic equivalents, providing sufficient activity in catalytic [2+2+2] cycloaddition reactions as well as appropriate stability. Further modifications resulted in air-stable and recyclable catalysts, which could be supported on a solid-phase, representing the first active, supported, CpCo(I)-based catalyst.