Tianyi Guan

About

This project examined how organometallic reactivity is controlled across chemically distinct catalytic systems, using palladium-catalyzed Wacker oxidation and adenosylcobalamin-dependent radical enzymes as complementary case studies. The analysis connected metal oxidation state, coordination environment, metal–carbon bond reactivity, catalyst regeneration, substrate activation, and local structural control to explain how transition-metal chemistry can be directed toward selective transformations in both industrial and biological settings.

Research Focus

To investigate how coordination environment, redox cycling, substrate binding, and active-site organization regulate transition-metal-mediated bond activation and selective catalysis across synthetic and biological systems.

Approach

A comparative, literature-based mechanistic analysis was conducted across two organometallic catalytic systems. The Wacker process was examined through the Pd(II) / Cu(II) co-catalytic cycle, including alkene coordination, nucleophilic attack, carbonyl formation, palladium reduction, and catalyst reoxidation. Adenosylcobalamin-dependent catalysis was analyzed through Co–C bond homolysis, radical generation, substrate transformation, and cofactor regeneration, with additional evidence from spectroscopy, mutagenesis, structural studies, and QM/MM calculations. The two systems were then compared to identify broader principles governing controlled organometallic reactivity.

Key Chemical Insights

Transition-metal catalysis can achieve selectivity through fundamentally different control strategies. In the Wacker system, catalytic turnover depends on coordinated substrate activation and coupled Pd/Cu redox regeneration, whereas adenosylcobalamin enzymes control highly reactive radical intermediates through substrate-triggered Co–C bond activation, hydrogen-bond reorganization, radical positioning, and active-site motion. Together, these systems illustrate how catalytic environments regulate otherwise highly reactive organometallic intermediates.

Keywords

Organometallic chemistry; transition-metal catalysis; Wacker oxidation; palladium catalysis; copper co-catalysis; adenosylcobalamin; vitamin B12; cobalt–carbon bond; radical catalysis; bioorganometallic chemistry; reaction mechanisms;