Elemental sulfur reacts with a bulky bis(phosphine)nickel(0) complex to give a monomeric nickel(II),eta(2)-disulfido complex, oxidation of which results in the elimination of sulfur with dimerization to give an eta(2),eta(2)-disulfidodinickel(II) derivative in which the S S bond can be reductively cleaved in a redox-reversible fashion.