UC Berkeley

Metal coordination complexes represent the chief reusable tools of chemical transformation. Their flexibility and controllability are responsible for the success of numerous fields, from production of feedstock chemicals to medicine to solar energy conversion. Here, several aspects of the behavior of coordination complexes are explored, including the relationship between ligand design and spectroscopic properties. First, the mechanism of vibrational population transfer in trincarbonyl(η4-diene)iron "piano stool" complexes is explored via temperature-dependent 2D-IR spectroscopy and density functional theory (DFT). The "wagging" motion of the carbonyl ligands is characterized, differentiating it from chemical exchange. Second, the structure and energy of hydroxypyridinone-based (HOPO) MRI contrast agents were explored via DFT. This understanding of medicinal metals could allow for directed synthesis of promising future contrast agent candidates. Finally, the dynamics of electronically excited cobalt-zirconium heterobimetallic complexes were investigated with time-resolved IR spectroscopy and DFT. A short-lived singlet metal-to-metal charge transfer state was characterized that mitigated the original goal of the complex: catalytic CO2 reduction chemistry. Together, these experiments expand the knowledge of important coordination complex behavior in ground and excited states.