Jh. Chou et al., STUDIES ON THE ELECTROACTIVE HETEROCYCLES C6S80 2- AND C6S6O20/2- ANDRELATED METAL-COMPLEXES/, Journal of the American Chemical Society, 120(8), 1998, pp. 1805-1811
The properties of the carbon sulfide C6S8 (1) as well as its dioxo ana
logue C6S6O2 (2) have been studied in the fully oxidized and fully red
uced forms, i.e., 1(0), 1,(2-) 2(0), 2(2-). A crystallographic study s
hows that compound 2 is a tricyclic species with a twisted 1,2-dithiin
(unsaturated C4S2 ring) core. Reduction of 1 with 2 equiv of LiBHEt3
gave C6S82- (1(2-)), which was isolated as its PP4+ salt. A crystallog
raphic study of this salt shows that reduction has resulted in cleavag
e of the S-S bond and that, in the solid state, the dihedral angle bet
ween the two rings is 180 degrees. Both 1(2-) and 2(2-) undergo two se
quential and reversible 1e(-) oxidations near 0 V (vs Ag/AgCl), thus e
stablishing that 1(0) and 2(0) are good oxidants relative to other dis
ulfides. Treatment of (PPh4)(2)[C6S8] with [Ni(H2O)(6)]Cl-2 afforded t
he dark red (PPh4)(2)[Ni(C6S8)(2)] (3). The analogous Pt complex (4) w
as also prepared. Crystallographic analysis of 3 shows that the nickel
center is square planar, comprising two seven-membered NiS2C4 rings.
The paramagnetism observed for solutions of 3 are attributed to the fo
rmation of a tetrahedral isomer.