SYNTHESIS OF CATIONIC IRON COMPLEXES WITH THE CYCLOBUTENYLIDENE LIGAND - CRYSTALLINE-STRUCTURE OF 1-TRIPHENYLPHOSPHONIUM-2-PHENYLVINYL-ETA5-CYCLOPENTA-DIENYLDICARBONYLIRON TETRAFLUOROBORATE

Stable, cationic, binuclear iron complexes with a new cyclobutenylidene bridge ligand {[Cp(CO)2Fe]2(Ph2C4H)}+ X- (X = ClO4, BF4) have been obtained by protonating the σ-phenylacetylide iron complex Cp(CO)2FeCCPh with the strong protonic acids HClO4 or HBF4 in acetic anhydride. In the presence of PPh3 this reaction results in the formation of metal-vinyl complexes containing the phosphonium cation {Cp(CO)2Fe[C(PPh3)CHPh]}+ X- (X = ClO4, BF4). When Cp(CO)2FeCCPh reacts with HClO4 or HBF4 in benzene, acetone or alcohol, [CpFe(CO)3]+ X- ionic complexes (X = ClO4, BF4) are formed. The structure of the above compounds has been confirmed by IR, 1H and 13C NMR spectra and X-ray analysis. © 1979.