Synthesis of (μ2,η3-allyl-η5-oxapentadienyl)diiron pentacarbonyl complexes, an unusual reaction product from η4-(vinylketene)Fe(CO)3 complexes: structure and electron density distribution analysis

The synthesis of a series of ferrocenylvinylketenes as stable eta(4)-[Fe(CO)(3)] complexes (3a-f) was successfully accomplished through the reaction of eta(2)-[Fe(CO)(4)] complexes under mild carbonylation conditions. The reactivity of 3a-f under thermal conditions afforded the unexpected formation of a novel family of (mu(2),eta(3)-allyl-eta(5)-oxapentadienyl)diiron pentacarbonyl complexes 5a-f proposed to be formed by a sequence metathesis-haptotropic rearrangement between the starting eta(4)-vinylketene iron(0) complex 3 and a eta(4)-vinylcarbene iron(0) complex trapped in situ after a reversible carbonylation process favored by the thermal conditions. An electron density distribution analysis (EDD) of 5e using high-resolution X-ray diffraction data in combination with the DFT framework was performed to understand the electronic communication between the two iron fragments.