Dr. Larry G. Sneddon, Chemistry Department, University of Pennsylvania, is supported by the Inorganic, Bioinorganic, and Organometallic Chemistry Program of the Chemistry Division to develop new general methodologies that enable the systematic, high yield preparation of polyhedral boron clusters. In this project a variety of new approaches for the syntheses and modification of polyhedral boron compounds will be designed. These include: new types of carbon and nitrogen cage-insertion reactions involving the nucleophilic attack of polyhedral boron anions on nitriles and polar-acetylenes; metal-catalyzed reactions of polyhedral boranes with acetylenes, olefins, and/or carbon monoxide; and new types of sulfur-atom insertion reactions leading to thia- and dithiaboranes. A second primary goal will be a systematic exploration of the chemistry and applications of the clusters which will be made available by the first part of the project. The polyhedral boranes are cage shaped molecules which possess unique chemical bonding and unusual properties. Besides being of theoretical interest, they are thought to be starting materials from which novel ceramics and polymers may be obtained. However, there are presently no good ways in which large quantities of the polyhedral boranes can be prepared in an economical fashion. The aim of this project is the development of new, efficient synthetic methods for the generation of these compounds. This will be accompanied by comprehensive investigations of the chemistry of the newly available molecules. These investigations will set the stage for the practical applications of polyhedral boranes as precursors to ceramic and polymeric materials.