Spectroscopic studies of ions and metal-containing molecules and complexes

Wesleyan University, Middletown CT

Investigators

Abstract

In this project funded by the Chemistry Structure and Mechanisms-A Program of the Chemistry Division, Professors Stewart Novick of Wesleyan University and Stephen Cooke of SUNY Purchase are using a microwave spectroscopy technique to study the interactions of hydrogen gas molecules (H2) and other small molecules that contain metal atoms. These studies seek to advance our understanding of how atoms interact to form molecules, and how molecules interact with each other. The Novick-Cooke team is also exploring other molecular systems, including those containing atoms of the so-called actinide elements, which contain many electrons and may form unusual chemical bonds and carbon-containing molecules with missing electrons (making them positive ions) which are implicated in molecule formation in the interstellar medium. This project involves graduate, undergraduate and post-doctoral researchers. The laboratory shared by Novick and Cooke is opened to many scientific visitors, allowing them to perform experiments that would be impossible for them in their home institution. The molecules, ions, and complexes are produced either by laser ablation or pulsed high voltage discharges coupled with supersonic expansion. The studies on these complexes, ions, and molecules are performed with the exquisitely sensitive and powerful high resolution technique of pulsed-jet Fourier transform microwave (FTMW) spectroscopy. The investigations of the intermolecular interactions between molecular hydrogen and transition metal compounds, for example the complexes H2-CuF, H2-CuCl, H2-AgCl, and H2 AuCl and have found that the bond strengths are surprisingly large (60 - 160 kilojoules per mole). The bonding is found to be very anisotropic but yet the hydrogen maintains its molecular identity in all the complexes studied. The detailed spectra, geometry and binding of H2 with CuO, ZnO, ZnS, AgF, and AuF are being investigated. The positive ion studies include the so-called Zundel ion, protonated water dimer, where the highest level calculations have the proton shared half-way between the two waters. Also being studied are uranium- and thorium-containing molecules where the f-electrons play an important role in the bonding.