The new anionic carbon sulfides C6S102- and C12S162- are described and crystallographically characterized. The C12S162-anion consists of two C6S8 units connected by an exceptionally long (2.157(12) Angstrom) S-S bond. In solution, C12S162-exists in equilibrium with the radical C6S8-.: The equilibrium constant for radical formation (293 K, THF) is 1.2 x 10(-4) M, as determined by optical spectroscopy at varying concentrations. Radical formation occurs through scission of the S-S bond. On the basis of variable temperature EPR spectra, the thermodynamic parameters of this process are DeltaH = +51.5 +/- 0.5 kJ mol(-1) and DeltaS = +110 +/- 3 J mol(-1) K-1. C6S102- is an oxidation product of C3S52- and consists of two C3S5 units connected by an S-S bond. The S-S bond length (2.135(4) Angstrom) is long, and the CS-SC torsion angle is unusually acute (52.1 degrees), which is attributed to an attractive interaction between C3S2 rings. The oxidation of (Me4N)(2)C3S5 occurs at -0.90 V vs Fc(+)/Fc in MeCN, being further oxidized at -0.22 V. The similarity of the cyclic voltammogram of (Me4N)(2)C6S10 to that of (Me4N)(2)C3S5 indicates that C6S102- is the initial oxidation product of C3S52-.