Reactions of bis(diphenylphosphine)acetylene with metal carbonyl complexes

The reaction of [Co₂(CO)₈] with DPPA at room temperature yields a diphosphine bridged product [Co₄(CO)₁₂(μ-Ph₂-P-C≡C-P-Ph₂)₂] 1. Heating of 1 at 45°C promoted cleavage of the P-C_sp bond with the formation of binuclear, phosphido-bridged σ-π-acetylide isomer complexes [Co₂(CO)₅(μ-PPh₂) (μ-σ-π-C≡C-PPh₂ )] 2a, 2b. Heating (60°C) of the complex [CpFe(CO)₂CH₃] and DPPA affords mono and binuclear acetyl, P-coordinated diphenylphosphinoalkyne metal complexes [CpFe(Ph₂P-C≡C-PPh₂)CO(COCH₃)] 3, [CpFeCO(COCH₃)]₂-μ-(Ph₂P-C≡C-PPh₂) 4.