This grant in the Inorganic, Bioinorganic, and Organometallic Chemistry Program supports the theoretical work of Dr. Thomas R. Cundari of the Chemistry Department, Memphis State University, on CH activation. Cundari will carry out five computational projects on the factors affecting the first step in catalytic methane conversion. Three of the projects involve methane activation by multiply-bonded Ti, Zr, and Hf complexes. The effect of pi-bond energy and polarity on the CH activation barrier will be explored, as well the effect of changing from amide to imide ligands. Other projects will examine metal-methyl complexes of lanthanides, Sc, and Zr. Oxidative addition and sigma-bond metathesis mechanisms for some Ir, Re, and W compounds will be modeled. The fifth project involves analysis of methane activation by electrophilic Pt(II) and Hg(II) complexes. In all cases, the computational results will be compared to experimental findings. The main goals of the study are to develop reliable methods for describing d- and f-block chemistry and to assess how CH activation is affected by the complex interaction of the metal, activating ligands, and ancillary ligands. A number of catalysts are available for the conversion of methane, which is abundant, to other organic products such as methanol, which is a transportable liquid fuel. For any conversion reaction, a carbon-hydrogen (CH) bond in methane has to be broken, or activated, and then other steps in the reaction can take place. Experimental data on a number of catalysts for reactions involving methane are known, but a common framework for understanding the role of the catalyst, which consists of a metal and accompanying groups, has not been developed. By carrying out computational studies on the electronic structure of the catalysts during these reactions, Cundari will identify important factors in the reaction and develop a broader view of the reaction mechanism. The research will aid in the development of more activ e and selective methane or alkane catalysts.
