The Co(II) porphyrin complex Co(TPP) is an efficient and versatile catalyst for selective olefination of carbonyl compounds, including aldehydes and activated and unactivated ketones, with ethyl diazoacetate (EDA) in the presence of triphenylphosphine. The catalytic reactions of aldehydes and activated ketones can be carried out in a one-pot fashion with the use of a stoichiometric amount of diazo reagents, affording olefins in high yields and high E selectivity. In the case of unactivated ketones, a substoichiometric amount of benzoic acid is required to promote the catalytic reactions.
The deposition of volatile cis-(CH 3 ) 2 Au(O,O′-acac) onto silica partially dehydroxylated at 400 °C leads to molecular dispersion of the organogold complex. X-ray absorption near-edge structure demonstrates that the gold retains its oxidation state upon binding. IR and 1 H magic-angle spinning NMR spectra suggest that the molecular framework also remains intact. Computational models involving hydroxyl-terminated octasilsesquioxane cube clusters to represent silica predict the most energetically favorable interaction to be hydrogenbonding between two surface hydroxyls and the oxygen donor atoms of the chelated acetylacetonate ligand. This mode of adsorption was confirmed by analysis of the IR and the Au L III edge extended X-ray absorption fine structure. The surface hydroxyls most likely to participate in the attachment of the gold complex to silica are vicinal silanol pairs that are not involved in hydrogen bonding to other silanols.
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