Dean C. Duncan

Multifunctional Polyoxometalates as Catalysts for Environmentally Benign Processes

Abstract In the face of declining natural resources and growing environmental deterioration, the coming generations of catalysts, and in particular oxidation catalysts, will need to address not only the conventional limitations of selectivity, rate and stability but also the emerging limitations imposed by the changing reality regarding resources and environment. An approach to develop flexible (modifiable) catalytic methodologies that addresses all these potential difficulties simultaneously will be presented. The use of multifunctional polyoxometalates as catalysts themselves or polyoxometalate fragments as catalytic components will be outlined.

Homogeneous Catalyzed Selective Oxidations Based on O2 or H2O2. New Systems and Fundamental Studies

We present here results that impact our fundamental knowledge regarding metal catalyzed O2 based oxidations and systems that address the mechanism of the Ishii/Venturello H2O2 based catalytic epoxidation chemistry. Our efforts continue to focus on fundamental energetic and mechanistic issues that define and indeed limit further development in the burgeoning area of selective catalytic oxidation. One particular application of a selective O2 based oxidation applied to an issue of practical and growing importance, the selective bleaching of wood pulp for paper manufacture, is a collaborative venture between our laboratories at Emory University and those of Dr. Weinstock and collaborators at the U.S. Department of Agriculture Forest Products Laboratory.

Dynamic behavior in the light and dark phases of alkane photochemical functionalization by [W10O32]4−

Picosecond irradiation of [W10O32]4−,1, indicates that this complex forms a ligand-to-metal charge-transfer (LMCT) excited state that decays withτ<30 ps to another much longer lived species (>15 ns) that is responsible for attack on alkane substrate and is distinguishable from the reduced complex, [W10O32]5−. Kinetics of production of reduced complex and the organic product (ethylalkane) in the presence of ethylene indicate that the role of1 in production of this product is not simply as an initiator of radical chain ethylene addition.