Synthesis and structure of the monometallic cationic complex [Cp(CO)2Fe{η2-(CH2CHCH2CH3)}]PF6 (Cp = η5-C5H5)

The bimetallic carbocation complex [{Cp(CO)2Fe}2(μ-C4H7)]PF6 reacted with trifluoroacetic acid to give the mononuclear cationic complex [Cp(CO)2Fe{η2-(CH2CHCH2CH3)}]PF6, which formed yellow orthorhombic crystals in the space group P212121 with a = 7.652(4), b = 13.422(7), c = 14.037(7); α = β = γ = 90.00 and Z = 4. The carbocation is coordinated to the metal in a η2-fashion forming a chiral metallacyclopropane type structure. The β-CH carbon (C9) is disordered over two positions (C9A and C9B), each having about 50% occupancy. This is attributed to there being both the R and S enantioface isomers in equal amounts in the crystal sample. NMR data indicate that the metallacyclopropane structure observed in the solid state is preserved in solution.

Graphical abstractThe reaction of trifluoroacetic acid in THF with [Cp(CO)2Fe(CH2CHCH2CH2)Fe(CO)2Cp]PF6 gave the chiral mononuclear cationic complex [Cp(CO)2Fe(CH2CHCH2CH3)]PF6, where the CH2CHCH2CH3 group is coordinated in a rigid η2-manner, in high yield. It formed yellow orthorhombic crystals in the space group P212121.Figure optionsDownload full-size imageDownload as PowerPoint slide