μ-η2:2-s-trans-Butadieneoctacarbonyldiiron(0) – Structural and spectroscopic properties

The crystal structure of [{Fe(CO)4}2(μ-η2:2-s-trans-C4H6)] was determined by single-crystal X-ray diffraction at 90 K. The complex is located on a center of symmetry in the triclinic space group P1‾. The central C–C bond of the s-trans-butadiene ligand is slightly longer compared to non-coordinated s-trans-butadiene. The Fe–Cax bond lengths are slightly longer than d(Fe–Ceq) in agreement with marginally shorter d(C≡Oax) compared to d(C≡Oeq). In addition, the title complex was characterized by IR and Raman as well as NMR spectroscopy and the data are interpreted by the aid of results of DFT calculations.