Six gallium(III) complexes with neutral N-donor ligands have been prepared and characterized; these include [Ga(L)2Cl2]Cl species with L = ethylenediamine, 5-nitro-1,10-phenanthroline, and 5-amino-1,10-phenanthroline as well as [Ga(L)Cl2]Cl complexes with L = bispicen, trispicen, and tpen. Although trispicen and tpen are potentially pentadentate and hexadentate, respectively, they appear to coordinate the Ga(III) metal center through only four donor atoms as assessed by NMR spectroscopy. The more electron-deficient phenanthroline derivatives promote faster alkene epoxidation, as assessed by the yields of epoxides measured at 1 h. The catalysis promoted by the pyridylamine ligands, while initially slower, persists for a longer period of time, with the yields of the epoxide steadily increasing over the course of at least 3 h. The complexes with the more highly coordinating trispicen and tpen ligands are less active than that with bispicen, suggesting that two readily exchangeable coordination sites are needed for optimum activity.

Influence of ligand electronics and denticity on the alkene epoxidation catalyzed by gallium(III) complexes

245th National Meeting (2013)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.