Acetylene–acetylide coupling via reactions of phosphido-bridged σ–π-acetylides with alkynes. X-Ray crystal structures of [Fe2(CO)5{PPh2C(O)C(But)CC(CO2Et)C(CO2Et)}] and [Fe2(CO)5{PPh2C(Ph)C(CO2Et)CC(But)CO}]

Abstract

Reactions of σ–πacetylides [Fe₂(CO)₆(C₂R¹)-(PPh₂)] with acetylenes R²CCR³ leads to acetylide-acetylene coupling and insertion into iron-phosphorus bonds generating novel organometallic derivatives [Fe₂(CO)₅{PPh₂C(O)C(R¹)CC(R²)C(R³)}](R¹= Bu^t; R = R³= CO¹Et) and [Fe₂(CO)₅{PPh₂C(R²)C(R³)CC(R¹)-C(O)}](R¹= Bu^t; R²= Ph; R³= CO₂Et) characterised by X-ray diffraction.