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Project Progress

Computational Chemical Modeling the Link Between Structure and Reactivity of Iron-Sulfur Motifs

(Szilagyi)

The multidisciplinary setting of ABRC facilitates a bidirectional communication between the experimental and theoretical teams. Using feedback from metalloenzymology, crystallography, electronic and X-ray absorption spectroscopy, photo-electron spectroscopy, attenuated total reflection Fourier transform infra-red vibrational spectroscopy, and molecular beam-surface collision experiments we have the critical amount of experimental input for developing and validating computational methodologies. The current computational activities are now focused on structurally and chemically well-defined systems, such as metalloenzymatic active sites and biomimetic small molecules of iron-sulfur clusters. Our recent success in generating viable hypothesis for the H-cluster biosynthesis (FEBS) and refining the catalytic active site of [FeFe]-hydrogenase with a combined crystallographic and computational approach (JACS) already well exemplify the power of our experiment-guided computational approach.

A novel aspect of our computational work is the development of coordination chemistry-based computational models for the iron-sulfur surfaces rather than using the traditional simulations with periodic boundary conditions. This is a novel concept and builds on the hypothesis that the catalytically active sites on surfaces are localized defect sites. Density functional theory is capable of capturing the most important electronic contribution to substrate binding and activation, as well as product release, while the molecular orbital and molecular mechanical theories provide an electrostatic and steric background, respectively.

We are currently assessing computationally what are the unique structural features and the molecular mechanistic details that are required for dinitrogen and dihydrogen activation processes with the aim of gaining an understanding into the likelihood of these processes being involved in abiotic small molecule activation processes.