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Research Interests

Research in our group covers a very broad spectrum--from gas-phase mechanistic studies to the synthesis and study of novel polymers which can be converted to ceramic fibers, or in some cases conduct electricity and possess unique optical properties. Thus, a student in this group receives an extremely broad-based research education in organic, organometallic, and materials chemistry.

We have long been intrigued by the drastic differences between the thermal behavior of organosilicon compounds and their all-carbon analogs. For example we have recently demonstrated through a combination of deuterium labeling, kinetics and theory that silacyclobutane 1 undergoes reversible ring-opening before (at higher temperatures) undergoing an extremely rare 1,3-shift of silicon to afford the ring-expanded isomer 3 via the intermediacy of carbene 2. In contrast the carbon analog (4) simply cleaves to ethylene and allene.

This propensity for unusual rearrangements is particularly profound in the thermal chemistry of organosilicon reactive intermediates. Thus for example we have discovered that transient compounds containing the silicon-sulfur double bond (e.g. 5, conveniently generated by retroene extrusion of propene) can cleanly rearrange to a divalent silicon, silylene 6.

Our group is very involved in the design, synthesis and study of polymers with unique optical properties. A recent example is our synthesis of the first conjugated polymers with cumulene units in the main chain. Polymer 7 has been found to have a strong ability to triple the frequency of light passing through its films, and thus has considerable potential for use in the next generation of optical switches.

An example of our work in "preceramic" polymers is our development of a "one-pot" synthesis of silicon-acetylene polymers (e.g. 8) which can be melt-spun into fibers which are ultimately fired to silicon carbide fibers of commercial quality. These same polymers are being used to "weld" ceramic bodies in order to create complex shapes without difficult and costly processing. Surprisingly when the same reaction is carried out with a 1,4-dichlorotetrasilane the first example of an acetylene in a 6-membered ring, 9, was formed in excellent yield. The study of such highly strained rings is an ongoing project in our group.