Despite the fact that Ni(CO)(4) was discovered more than a century ago, no neutral Ni-2(CO)(y) compound has ever been synthesized in macroscopic amounts. In this study we consider a number of such compounds, including the Ni-Ni single-bonded (mu-CO)Ni-2(CO)(6), the Ni=Ni double-bonded (mu-CO)(2)Ni-2(CO)(4), and the N drop Ni triple-bonded (mu-CO)(3)Ni-2(CO)(2). The predicted central bond distances are 2.73 (Ni-Ni), 2.56 (Ni= Ni), and 2.20 Angstrom (Ni drop Ni). The latter compound is predicted to be bound by 34 kcal/mol with respect to Ni(CO)(4) + NiCO. Prospects for the synthesis of related dinickel compounds are discussed in some detail.