Constitutional isomers, stereoisomers and conformers of bis[di-tert-butyl(trimethylsilyl)cyclopentadienyl]disulfane

Reaction of tBu2(Me3Si)C5H2Li with S2Cl2 leads to [tBu2(Me3Si)C5H2]2S2. This compound exists as a pair of diastereomers (1,2) with sulfur in an allylic position of the cyclopentadiene system. Each diastereomer exists as a racemate of RS,SR and RR,SS enantiomers, respectively. 1 rapidly, 2 slowly convert below room temperature to a pair of diastereomers (3,4) with sulfur in vinylic position. Again, each diastereomer exists as a racemate of RS,SR and RR,SS enantiomers. 3 and 4 are the stable constitutional isomers at ambient temperatures and do not interconvert. The structures of 2, 3 and 4 have been determined by single crystal X-ray diffraction.