This award will support collaborative research between Dr. Peter P. Gaspar, Washington University and Dr. Francois Mathey, Laboratoire de Chimie du Phosphere et des Metaux de Transition, Palaiseau, France. The objective of the project is the preparation and study of an unusual, short-lived chemical species, a phosphorus-containing molecule called phosphinidene. It is believed that these molecules will have extremely unusual properties and that the study of phosphini- denes will further the understanding of fundamental principles of chemical reactivity, as well as lead to the synthesis of new kinds of molecules, including some biochemical interest. As a benchmark for the applications of ab initio calculations in organometallic chemistry, there is a need to compare the actual structures and detailed reaction paths of phosphinidenes and their metal complexes with theoretically predicted structures and mechanisms. The investigators plan to carry out a series of experiments to include the synthesis of a sterically hindered phophirane-metal complex, whose thermal or photochemical decomposition should form a phosphinidene- metal complex sufficiently long-lived for direct spectroscopic observation. This project will benefit from the complementary experimental expertise of the two investigators. Dr. Mathey and his colleagues have considerable experience in the synthesis of metal-phosphine complexes, including phophiranes and their demetallation. Dr. Gaspar's laboratory has perfected the adamantylation of main group hydrides and the photochemical as well as thermal decomposition of related three-membered rings such as siliranes. This project should provide the opportunity to develop new routes to interesting and useful reactive intermediates that have thus far eluded detailed study. Phosphinidenes hold great promise both for the synthesis of organophosphorus compounds and for the mechanistic studies aimed at increasing control of reaction pathways by subtle changes in electronic structures. Results of this research may clarify how the ideas of organic chemistry must be modified to deal with bond-making and bond-breaking phenomena below the first row of the periodic table.
