Improved synthesis of di- and trinuclear iron carbonyl complexes containing bridging diphenylethenyl ligand.: X-ray structure of [PPh4][Fe2(CO)6(μ-CO)(μ-PhCCHPh)]

The cluster anion [PPh4][HFe3(CO)11] (1) reacts with one equivalent of methyl iodide and diphenylacetylene in acetone at room temperature to give the dinuclear complex [PPh4][Fe2(CO)6(μ-CO)(μ-PhCCHPh)] (2) in high yield. The same reaction performed in boiling acetone yields only the trinuclear cluster [PPh4][HFe3(CO)9(μ-PhCCPh)] (3). When the reaction of [PPh4][HFe3(CO)11] (1) is carried out with an excess of methyl iodide at room temperature, the dinuclear neutral complex [Fe2(CO)6{μ-CPhCPhCH(OCH3)}] (4) is obtained as a sole product of the reaction. Complex 2 was characterized by X-ray analyses.