Reactivity of multi-site bound allenylidene towards alkynes and silica gel

摘要

Heating the allenylidene species [Ru_3(CO)_9(#mu#-CO)(#mu#_3-C=C=CPHh_2)] in the presence of alkynes RC_2R (R=Me or Ph) led to formation of the novel complexes [Ru_3(CO)_9{#mu#_3-C(R)C(R)C_2CPh_2}](R=Me or Ph) and [Ru_4(CO_(12){#mu#_4-C(Ph)C(Ph)CCCPh_2}], shown by X-ray diffraction to contain C_5 ligands formed through carbon-carbon bond formation with the #alpha#-carbon of the allenylidene unit. Adsorption of [Ru_3(CO)_9(#mu#-CO)(#mu#_3-C=C=CPh_2)] onto silica gel at room temperature leads to formation of the acetylide species [Ru_3(CO)_9(#mu#-H){#mu#_3-C=CC(Ph)_2OH}], whereas reaction of [Ru_3(CO)_9(#mu#-CO){#mu#_3-C=C=C(Ph)Me}] with silica gel affords [Ru_3(CO)_9(#mu#-H){#mu#_3-C=CC(Ph)=CH_2}], containing an ene-yne ligand. Some insights into the mechanisms by which the transformations take place are given.