Mo and pterin

The earliest period of work on pterin models for Moco followed the discovery of the pterin unit within Moco, and occurred prior to the confirmation of the dithiolene chelate. These early studies explored the coordination chemistry between molybdenum and pterins or other structurally related molecules such as pteridines (Figure 2.1, top). The resulting themes of this body of work include the favorable coordination by molybdenum in several oxidation states to the 04, N5 chelate site in pterin (see Figure 2.1 for numbering), a variety of reactivities exhibited by Mo -tetrahydropterin systems and the highly delocalized electronic structures in molybdenum-pterin complexes that defy formal oxidation state assignments to Mo and pterin. 

Model Exploration of Redox Processes Between Mo and Pterin... 

Pterin-Molybdenum Redox Chemistry. The early studies focused on Mo(vi) and tetrahydropterin reagents to closely mimic the Mo and pterin portions of Moco. These studies showed that a variety of dioxo-Mo(vi) complexes reacted with tetrahydropterins to produce intensely colored mono-0x0 Mo complexes, but the reports offered different interpretations of what reaction had occurred and what resulting oxidation states of molybdenum and pterin had been produced, even when X-ray structures of the product Mo-pterin complexes were available. A clear picture of the electronic structure was eventually developed from redox titrations, reactivity studies, theoretical calculations and X-ray photoelectron spectroscopy (XPS) studies. 

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