Synthesis and characterization of oxomolybdenum(V) compounds with two or three thiolate donor atoms: Analogues for the molybdenum center of sulfite oxidase

Abstract

The MoOS₃ active site of sulfite oxidase has drawn attention to a relatively unexplored area of molybdenum coordination chemistry. Cis,trans-(L-N₂S₂)MoᵛO(SR)[L-N₂S₂H₂ = N,N '-dimethyl-N,N'-bis(mercaptophenyl)ethylenediamine: R = CH₂Ph. CH₂CH₃, and p-C₆H₄-Y (Y = CF₃, Cl, Br, F, H, CH₃, CH₂CH₃, and OCH₃)] are the first structurally, spectroscopically, and electrochemically characterized mononuclear Mo compounds with three thiolate donors in the equatorial, as occurs in sulfite oxidase. These compounds provide a well-defined platform for the systematic investigation of the electronic structures of the MoᵛOS₃ centers and their implications for molybdoenzymes. Single crystal electron paramagnetic resonance spectroscopy was used to study cis,trans-(L-N₂S₂)MoᵛOCl and determine the relationship between the molecular and magnetic structure. These studies furnish a better understanding of the CW-EPR parameters exhibited by the various Mo(V) forms of the mononuclear molybdenum enzymes.