Ene-l,2-dithiolates

Mo counterparts, the dimensions of the dithiolene ligands suggest that each is present at the ene-l,2-dithiolate oxidation level. 

Enedithiolate anions are redox-active ligands (see equation 1), capable of coordinating with a variety of metals as neutral dithioketones (1), thioketone radical thiolate monoanions (2) and ene-l,2-dithiolate dianions (3). The complexes are named dithiolenes irrespective of their oxidation state to remind one that they are noninnocent ligands . 

Figure 1 Structure of molybdopterin or preferably the metal-binding pyranopterin ene-l,2-dithiolate (MPT) the phosphate group may be bound to a nucleotide.

J. P. Dieks, M. Zubair, E. S. Davies, C. D. Garner, C. Schulzke, C. Wilson and J. MeMaster, Synthesis, Strueture and Redox Properties of Asymmetric (Cyclopentadienyl)(ene-l,2-dithiolate)cobalt(III) Complexes Containing Phenyl, Pyridyl and Pyrazinyl Units, Eur. J. Inorg. Chem., 2015, 3550-3561. 

Figure 6.8 Synthesis and crystallographically determined structure of the Mo 0 complex coordinated by two inequivalent ene-l,2-dithiolate ligands.

The mARC enzymes are the most recently discovered pyranopterin Mo enzymes found in mammals, and they possess a high degree of sequence similarity to the MOSC domains found in the Moco sulfurases. Similar to the XO and SO family enzymes, these small proteins possess a single PDT that is bound to the Mo ion via the ene-l,2-dithiolate chelate. The mARC enzymes are small proteins ( 35 kDa) that are found in the outer mitochondrial membrane. These enzymes possess broad substrate specificity " ... 

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