The photochemical reaction of Os3(CO)10(μ-H)(μ-γ-C5H3O2), a triosmium cluster carrying a γ-pyrone ligand, with dimethylacetylenedicarboxylate: formation of isomeric clusters

Reaction of the cluster Os3(CO)10(μ-H)(μ-γ-C5H3O2) (1), with DMAD under UV irradiation afforded three isomers of the monosubstituted product, Os3(CO)9(μ-γ-C5H3O2)(μ3-MeO2CCHCCO2Me) (2), and a disubstituted product, Os3(CO)8(μ-γ-C5H3O2)(μ3-MeO2CCHCCO2Me)(μ-MeO2CCCCO2Me) (3). The formation of 3 suggests that flipping of the O-heterocycle can occur.