Nucleophilic and Electrophilic Behavior of the Phosphinidene-Bridged Complex [Fe2(η5-C5H5)2(μ-PCy)(μ-CO)(CO)2]

The phosphinidene-bridged complex [Fe2Cp2(μ-PCy)(μ-CO)(CO)2] ( 1 ) reacts with HCCR (R = p-tol, CO2Me) to give products incorporating one or two alkyne molecules and involving further coupling with Cp or CO ligands, as shown by the formation of the complexes [Fe2Cp{μ-η5:κ1-C5H4PCyCHCH(p-tol)}(CO)3], [Fe2Cp2{μ-κ1:κ1,η1-CyPCHC(p-tol)C(O)}(μ-CO)(CO)], and [Fe2Cp2(μ-CO)2(CO){PCy(CHCHCO2Me)(C2CO2Me)}]. In contrast, the reactions of 1 with benzyl azide or (trimethylsilyl)diazomethane initially give the simple 1:1 adducts [Fe2Cp2(μ-CyPN3CH2Ph)(μ-CO)(CO)2] and [Fe2Cp2{μ-CyPN2CH(SiMe3)}(μ-CO)(CO)2], respectively, although the latter rearranges to yield [Fe2Cp2{μ-κ1:κ1,η1-CyPN(SiMe3)NCH}(μ-CO)(CO)] under photolytic conditions.