Tungsten complexes dithiolene

Prior to a consideration of oxo-molybdenum and oxo-tungsten bis(dithiolene) complexes, and as a link to the pyrazolylborato complexes discussed in the latter part of Section II, mention will be made of the dithiolene complexes, [(L-... 

Lowe and Garner (1993a,b) have synthesized three new dithiolene ligands and formed complexes with a variety of transition metals (Fig. 23) including molybdenum [40]-[42], tungsten [43] and [44] and nickel [45]—[48]. The electrochemical properties of the complexes and free ligands were studied by... 

Bis[iV,iV -di(2-pyridyl)-imidazol-2-ylidene]aurate(I) tetrafluoroborates, preparation, 2, 292-293 Bis[iV,iV -di(2-pyridyl-methyl)-imidazol-2-ylidene]aurate(I) tetrafluoroborates, preparation, 2, 292-293 Bis(diselenolate) complexes, dinuclear iron compounds, 6, 242 Bis(dithiolene) compounds, in tungsten carbonyl and isocyanide complexes, 5, 644 Bis(enolato) complexes, with bis-Cp Ti(IV), 4, 589 Bis(enones), in reductive cyclizations, 10, 502 Bis(ethanethiolato) complexes, with bis-Cp Ti(IV), 4, 601 Bis(ethene)iridium complexes, preparation, 7, 328-329 -Bis(fluorenyl)zirconocene dichlorides, preparation,... 

The final topic addressed in this chapter is the biosynthesis of the dithiolene cofactor ligand and its coordination to molybdenum and tungsten in the enzymes. Nature has clearly devised a synthetic process to overcome the twin difficulties of building a reactive dithiolene unit bearing a complicated and equally reactive pterin substituent. Molecular biology has been the tool to elucidate the steps in this complex process. Although the dithiolene formation step remains mainly a subject of conjecture, definitive information about the reagent molecule that will eventually be converted to a dithiolene is known. 

Figure 11. Scheme showing synthetic routes to mono- and binuclear bis(dithiolene)tungsten(IV) and (V) complexes from [W(CO)2(S2C2R2)2] (R = Me or Ph) (83, 85-87). 

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