The ability of the title compound to promote C–C coupling processes has been analyzed by examining its reactions with diazoalkanes, alkynes, and other unsaturated organic molecules. The title compound reacted with N2CPh2 at room temperature to give a mixture of ketenyl complex [Mo₂Cp2{μ-κ1:η2-C(Ph)CO}(μ-PCy2)(CO)(κ1-N2CPh2)] and carbyne complex [Mo2Cp2(μ-CPh)(μ-PCy2)(CO)(κ1-N2CPh2)], products which can be converted into each other by addition/removal of CO, respectively. In contrast, denitrogenation took place rapidly in analogous reactions with diazomethane and benzylazide at room temperature, to yield, respectively, the corresponding alkenyl [Mo2Cp2{μ-κ1:η2-C(Ph)CH2}(μ-PCy2)(CO)2] and iminoacyl [Mo2Cp2{μ-C(Ph)NCH2Ph}(μ-PCy2)(CO)2] derivatives, following from selective C–C and C–N couplings. The title compound reacted at 333 K with methyl propiolate to give the corresponding propenylylidene derivative [Mo2Cp2{μ-κ2:η3-CPhCHC(CO2Me)}(μ-PCy2)(CO)2], as a result of selective coupling of the carbyne ligand to the terminal carbon of the alkyne. A related complex could be obtained when using the internal alkyne dimethyl acetylenedicarboxylate.