Metallacarboranes of Main Group, Transition, and Lanthanide Elements: Syntheses, Structures and Reactivities

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The Inorganic, Bioinorganic, and Organometallic Chemistry Program of the Chemistry Division supports Dr. Narayan S. Hosmane, Department of Chemistry and Biochemistry Northern Illinois University, for research into the synthesis, structure, and reactivity of metallacarboranes of main-group, transition, and lanthanide elements. The project has three main thrusts. The first is the development of a convenient, safe synthesis of natural and 10B-enriched C2B4-carboranes from readily prepared and/or available borane reagents, such as the Na(B3H8). The objective is a preparative route that does not require a vacuum line, thus enabling laboratories not experienced in the manipulation of boranes and carboranes to utilize these compounds. Secondly, a variety of ionic and neutral metallacarboranes, containing metals spanning groups 2-14, will be prepared using active-metal mediated reductive cage-opening reactions, with concomitant metalation of the opened carborane face. The specific purpose is to obtain a range of compounds- from water-soluble metallacarborane salts to lipophilic neutral metallacarboranes-of both the constrained geometry half- and full-sandwich organometallic species. Finally, cationic electrophilic metallacarboranes will be prepared with C2B4- and C2B9- or C2B10- carboranes both coordinating to the metal and serving as weakly coordinating anions. These will be studied as catalysts for olefin polymerization. The goal of this research is to produce a number of new and novel compounds containing cages of carbon and/or boron combined a wide range of metals. While cage compounds containing carbon and boron have been known for some time, they require very sophisticated techniques in order to prepare them conveniently and safely. Thus, the first part this project will be the design new preparative procedures that will allow these species to be synthesized in typical laboratories. The next section will develop routes to a variety of boron-carbon cage molecules that are stable under normal environmental conditions. The highly water- and fat-soluble species might be useful in applications such as Boron Neutron Capture Therapy and in homogeneous catalysis. The students involved in this project, both graduates and undergraduates, will learn a breadth of synthetic skills. Additionally, they will be involved with a number of collaborators at several national laboratories, other universities and research institutions, and at BP/Amoco. Thus they will take part in a true interdisciplinary research project at the interface of science and engineering.