This award in the Inorganic, Bioinorganic, and Organometallic Program supports the research of Dr. Michael Lattman of the Chemistry Department, Southern Methodist University, on the chemistry of hypervalent main group elements and some transition metals. Elements are described as "hypervalent" when they are formally surrounded by more than eight electrons and contain a three-center four-electron bond. Lattman will investigate the behavior of these elements with nitrogen- and oxygen-containing macrocycles, specifically members of the cyclen and calixarene families. Basic relationships of ring size, atomic size and geometry will be determined, as will amphiprotic behavior. Some metals will be placed in phosphorylated calixarene "baskets." %%% Large cyclic organic molecules which contain nitrogen or oxygen can use electrons available on the nitrogen or oxygen to bond to metals or other elements. Factors such as ring size and position of the heteroatom impose geometric constraints on the molecule formed, making it possible to stabilize atoms in unsual geometries or oxidation states and to influence their reactivity. Lattman will study some elements in unusual environments to obtain fundamental information on their behavior. It is possible that the results may be relevant to the stabilization of heterobimetallic compounds, shape selective catalysis, and nonlinear optical behavior.
