Chemistry of vinylidene complexes. XX. Intramolecular carbonylation of vinylidene on the MnFe center: Spectroscopic and structural study. X-ray structure of the new trimethylenemethane type MnFe complex

Reactions of Fe2(CO)9 with Cp(CO)2MnCCHPh (1) and Cp(CO)(PPh3)MnCCHPh (3) gave the heterometallic trimethylenemethane complexes η4-{C[Mn(CO)2Cp](CO)CHPh}Fe(CO)3 (2) and η4-{C[Mn(CO)(PPh3)Cp](CO)CHPh}Fe(CO)3 (4), respectively. The formation of the benzylideneketene [PhHCCCO] fragment included in complexes 2 and 4 occurs via intramolecular coupling of the carbonyl and vinylidene ligands. The structures of 3 and 4 were determined by single crystal XRD methods. The influence of the nature of the L ligands at the Mn atom on the structural and spectroscopic characteristics of η4-{C[Mn(CO)(L)Cp](CO)CHPh}Fe(CO)3 (L = CO (2), PPh3 (4)) is considered. According to the VT 1H and 13C NMR spectra, complex 2 reversibly transforms in solution into μ-η1:η1-vinylidene isomer Cp(CO)2MnFe(μ-CCHPh)(CO)4 (2a), whereas complex 4 containing the PPh3 ligand is not able to a similar transformation.

Heterometallic trimethylenemethane complexes η4-{C[Mn(CO)(L)Cp](CO)CHPh}Fe(CO)3 (L = CO (2), PPh3 (4)) were formed from reactions of Fe2(CO)9 with Cp(CO)(L)MnCCHPh (1, 3). Complex 2 in solutions is in equilibrium with the μ-vinylidene isomer Cp(CO)2MnFe(μ-CCHPh)(CO)4, while new complex 4 exists both in solid and in solutions in the trimethylenemethane form, as it was shown by XRD, NMR and IR spectroscopy.Figure optionsDownload as PowerPoint slideResearch highlights
► Intramolecular carbonylation of vinylidene occurs by action of Fe2(CO)9 on Cp(CO)(L)MnCCHPh.
► Trimethylenemethane η4-{C[Mn(CO)2Cp](CO)CHPh}Fe(CO)3 exists in solutions in equilibrium with the μ-vinylidene isomer.
► New complex η4-{C[Mn(CO)(PPh3)Cp](CO)CHPh}Fe(CO)3 was synthesized and full characterized.