Activation of elemental sulfur by the monovalent nickel complex [PhTt(tBu)]Ni(CO) [PhTt(tBu) = phenyl{tris[(tert-butylmethyl)thio]methyl}borate] generates the disulfidodinickel(II) complex 2. This species is alternatively accessible via thermal decomposition of [PhTt(tBu)]Ni(SCPh3). Spectroscopic, magnetic, and X-ray diffraction studies establish that 2 contains a mu-eta(2):eta(2)-S-2 ligand that fosters antiferromagnetic exchange coupling between the Ni-II ions. This observation is in contrast to the lighter congener, oxygen, which strongly favors the bis(mu-oxo)dinickel(III) structure. 2 oxidizes, PPh3 to SPPh3 and reacts with 02, generating several products, one of which has been identified as [(PhTt(tBu))Ni](2)(mu-S) (3).