Marion E. Cass

Please follow these links for more information:

• Education and Research Experience, Publications, Interactive Teaching Web Pages
• Courses: Carleton College

Teaching Interests:

Inorganic Chemistry, Molecular Orbital Theory, Inert Atmosphere Synthesis, Introductory Chemistry, Chemistry for Non-Science Majors, Energy Production and Consumption, and Scientific Glassblowing

Research Interests:

 Since 2004, I have been collaborating with Professor Henry Rzepa (from Imperial College, London) to examine the mechanisms by which molecules scramble atom positions without breaking chemical bonds. A major emphasis of our work has been to develop interactive visualizations to facilitate the understanding of these molecular processes. Using computational methods we have been able to find the transition states and to visually examine the molecular motion for the Berry Pseudorotation (in PF₅, SF₄, and Sn(amidinate)₂), the Lever Mechanism (in ClF₃ and in one high energy pathway for SF₄), the Turnstile Mechanism (which results in cis/trans isomerization for the computational model SF₄Cl₂), and the Bartell Mechanism (in IF₇). In addition, although square pyramidal molecules were also known to undergo intramolecular rearrangements, no mechanistic analysis had been performed. We located the transition states and computed the activation barriers for several AX₅ molecules and discovered that they passed through one of two types of transition states; one of C_s symmetry (for BrF₅, IF₅) or one of C_2v symmetry (for ClF₅, ICL₅ and IBr₅) and although these two mechanisms share some similar types of motions, the two rearrangement processes are distinctly different. More recently we have been studying the Bailar Twist and Rây-Dutt Mechanisms (variants of the twist mechanism) that racemize &Lambda and &Delta forms of Metal Tris-Chelates.

Previously my research interests were focused in two general areas. When I first came to Carleton, I examined the relationship of molecular structure to specificity in binding of metal ions by naturally occurring metal ion sequestering agents. Specifically, I aspired to learn more about the specificity acheived in binding the vanadium(IV) ion by the N-hydroxy-2,2'-iminodipropionic acid ligand found in the mushroom Amanita muscaria. We designed and synthesized new chelating agents and then examined the coordination chemistry of our ligands with vanadium(IV) and other metal ions. I also have been interested in the design and synthesis of inorganic dye molecules to be used as sensitizers in titanium dioxide dye-sensitized solar cells. During the 1994-95 and 1995-96 academic years, I was on leave from Carleton at the California Institute of Technology working with Professor Nate Lewis and his research colleagues. Our research involved synthesizing and characterizing new and previously known dye sensitizers. We fabricated solar cells with these dyes to be used in a variety of comparative tests to help us gain an understanding of the fundamental limitations of these types of solar cells in energy conversion processes.

Back to The Chemistry Department Homepage

 This page is created and maintained by Marion E. Cass.
If you have questions or comments, please send E-mail.