click on the pictures at right for other research projects in the Burgmayer Research group

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molybdenum cofactor modeling-- --ruthenium interactions with DNA

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metals & pteridines--- --molybdenum tris-dithiolenes--

"Hyper-paramagnetic" Molybdenum tris-dithiolene complexes

Molybdenum dithiolene compounds have been well-studied because of their variable coordination geometries , unique properties and because a Mo-dithiolene group is present in the pterin-containing molybdenum enzymes.(1) We have discovered a class of molybdenum(+4) tris-dithiolenes that exhibit unprecedented magnetic behavior. In contrast to most molybdenum(+4) tris-dithiolenes that are known to be diamagnetic, we find that tris-dithiolenes bearing quinoxaline and aromatic substituents produce Mo(+4) complexes with “hyper-paramagnetic” behavior. Room temperature magnetic susceptibility measurements on these compounds have been observed as high as 8.0 BM, a value far in excess of that expected for a Mo(+4) d2 center. We are probing the structural parameters that favor this unusual property by synthesizing derivatives with variable aromatic substituents on the dithiolene ligands. UV/vis spectroscopy and cyclic voltammetry tools are used to probe the electronic structure in the new derivatives.

(1) Dithiolene Chemistry, Progress in Inorganic Chemistry, Vol. 52, E. I. Stiefel, Ed., Wiley, New Jersey, 2004.