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 Fe 2 (CO) 9 with Cp(CO) 2 Mn C CHPh ( 1 ) and Cp(CO)(PPh 3 )Mn C CHPh ( 3 ) gave the heterometallic trimethylenemethane complexes η 4 -{C[Mn(CO) 2 Cp](CO)CHPh}Fe(CO) 3 ( 2 ) and η 4 -{C[Mn(CO)(PPh 3 )Cp](CO)CHPh}Fe(CO) 3 ( 4 ), respectively. The formation of the benzylideneketene [PhHC C C O] 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 η 4 -{C[Mn(CO)(L)Cp](CO)CHPh}Fe(CO) 3 (L = CO ( 2 ), PPh 3 ( 4 )) is considered. According to the VT 1 H and 13 C NMR spectra, complex 2 reversibly transforms in solution into μ-η 1 :η 1 -vinylidene isomer Cp(CO) 2 MnFe(μ-C CHPh)(CO) 4 ( 2a ), whereas complex 4 containing the PPh 3 ligand is not able to a similar transformation.