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)2Mndouble bond; length as m-dashCdouble bond; length as m-dashCHPh (1) and Cp(CO)(PPh3)Mndouble bond; length as m-dashCdouble bond; length as m-dashCHPh (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 [PhHCdouble bond; length as m-dashCdouble bond; length as m-dashCdouble bond; length as m-dashO] 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-Cdouble bond; length as m-dashCHPh)(CO)4 (2a), whereas complex 4 containing the PPh3 ligand is not able to a similar transformation.