Research

The Gaspar group is trying to solve fundamental problems in organic and main group chemistry, and to put our new knowledge to practical use. We are learning how the mechanistic ideas of organic chemistry can be extended to explain and predict the making and breaking of covalent bonds throughout the periodic table. Our study of reactive intermediates and their reaction mechanisms allows us to make new molecules, new types of bonds and even new materials.

We study the reactions of molecules and ions small enough to be characterized by spectroscopic measurements and to be investigated by both experiments and theoretical calculations. Many of these are electron-deficient species that are heavier analogs of the common reactive intermediates of organic chemistry such as carbenes, carbocations, carbanions and free radicals. Some of our most fruitful experiments involve the conversion of reactive intermediates through trapping reactions and rearrangements into products whose structures reveal the mechanisms of their formation and thus clarify the chemistry of the species studied. These reactions are often entirely new, and their products may be molecules not previously accessible. Thus the reactions we study provide new synthetic tools.

Graduate students in the Gaspar group are provided with a training that prepares them for a variety of careers because our work involves a broad range of activities: the all-important synthesis of precursor molecules, reaction studies starting with the isolation and characterization of products, computational modeling of reactions to predict their mechanisms, and instrumental studies of reactions and their rates by such techniques as mass spectrometry of ion-molecule reactions and kinetic spectroscopy by laser-flash photolysis and time-resolved ESR measurements.

Among our current passions is the study of molecules and ions with only four valence electrons (carbenes and their analogs have six). These have the potential, as shown below for monovalent silicon cations, of forming three bonds in a single reactive collision (carbenes and their analogs can form two bonds simultaneously) thus opening up a variety of exciting opportunities for new and synthetically useful, reactions.

Selected Publications

• Xinping Liu, Diana Ivanova, Daryl Giblin, Michael L. Gross, Peter P. Gaspar, "Gas-Phase Synthesis, Characterization, and Reactivity Studies of the Prototype Aromatic Phosphirenylium Ion," Organometallics, 24, 3125 - 3135 (2005)
• Peter P. Gaspar, Xinping Liu, Diana Ivanova, David Read, James S. Prell, Michael L. Gross, "Four-Valence Electron Reactive Intermediates and the Philicity of Charged Carbene Analogs," Modern Aspects of Main Group Chemistry, M. Lattman, ed., American Chemical Society Symposium Series 917, Washington, DC, 2005, pp. 52-65.
• Rosa Becerra, Peter P. Gaspar, Cameron R. Harrington, William J. Leigh, Ignacio Vargas-Baca, Robin Walsh, Dong Zhou, "Direct Detection of Dimethylstannylene and Tetramethyldistannene in Solution and the Gas Phase by Laser Flash Photolysis of 1,1-Dimethylstannacyclopent-3-enes," J. Am. Chem. Soc., 127, 17469-78 (2005).