Allenyl-bridged complexes, structure

Seyferth and co-workers described the preparation and spectroscopic characteristics of a series of jU,-r, T)--allenyl-bridged complexes [Fc2-(CO)6(/i-SR)(ju,-i7, i7"-HC=C=CH2)] (34) for which the methylene protons appeared equivalent at room temperature (23). A close structural similarity between the allenyl bonding mode and that of a bridging a-ir-vinyl was noted and led to the suggestion that the allenyl and vinyl ligands underwent a similar fluxional process (Scheme 37). 

Figure 3. Structural changes induced by the coordination of dppm to a phosphido-bridged allenyl diruthenium complex.

Allenyl ligands bridging two metal atoms exist in one of two common structural types (H) and (J). Both H and J type complexes... 

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