In this project, funded by the Chemical Catalysis Program of the Chemistry Division, Professor Clemens Krempner of Texas Tech University examines the use of frustrated Lewis pairs (FLPs) as replacements for expensive, less abundant, and toxic precious metals used in the catalytic hydrogenation of unsaturated organic species. FLPs are sterically-encumbered Lewis acid-base pairs of unquenched reactivity due to their inability to form classical Lewis-acid-base complexes. Novel combinations of Lewis acids and bases, capable of reversibly cleaving dihydrogen, are identified by a combined computational / experimental approach. Attractive weak Lewis acids include boronic and boric esters, as these compounds are readily synthesized from inexpensive starting materials or are commercially available at low cost. Phosphazenes and guanidines are used as the base components. Progress in catalyst development is amplified by the combination of modular FLP synthesis, detailed catalytic testing, and computational investigations on novel catalysts and the underlying catalytic mechanisms.
This project is performed in collaboration with Professor Shuhua Li (Nanjing University, Nanjing, China) and Professor Juergen Klankermayer (RWTH Aachen, Aachen, Germany). Together, these three groups combine their separate areas of expertise to produce transition metal-free hydrogenation of imines, ketones and olefins - important substrates in the pharmaceutical industry. The broader impacts of this work include leadership training for postdoctoral fellows and graduate and undergraduate students and an international exchange of ideas and expertise.
