1,2,3-Selenadiazoles as precursors to cyclopentadienylcobalt dithiolenes and 1,4-dithiins: molecular structures of bis(cycloocteno)-1,4-dithiin and bis(cycloocteno)-1,4-diselenin

Cycloocteno-1,2,3-selenadiazole ( 1 ) and cyclopenta-dienyldicarbonylcobalt ( 2 ) react in the presence of an excess of elemental sulfur to yield the dithiolene cyclopentadienyl(1,2-cyclooctenedithiolato)cobalt ( 3 ). Available evidence indicates that this reaction involves the intermediacy of a cobalt–alkyne complex. Compound 3 is the first example of a cyclopentadienylcobalt dithiolene bearing aliphatic substituents. Analogous reactions performed using only catalytic quantities of 2 provide high-yield syntheses of bis(cycloocteno)-1,4-dithiin ( 6 ) and bis(cycloocteno)-1,4-diselenin ( 7 ), whose structures have been determined by X-ray diffraction.