The addition of different Lewis bases to solutions of "(CoF5)2Ni" in THF-Dioxane or solutions of previously isolated (CoFs)2Ni Dioxancs gives neutral and anionic bispentafluorophenyl nikel (11) complexes.All the previously isolated neutral complexes were of the type (CoF=)2Ni U being U = 2PEt3, 2PBu3, 2PPh3, 2AsPh3, 2SbPh3. 20PPh3, 20AsPh3, 2p-dioxane, 2PPh2Cl, 2NH3 2py, bis diphenylphosphine-ethane, ethylenediamine, 2.2' bipyridine and- 1,10—fenantroiine, (5,6). Anionic complexes here described are binuclear with different bridge groups of the type [(CoF5)2 NÍX2NÍ (CoF5)2]~^ being X = CN, Cl, Br. The bridge system is broken by PPha when X = CN to give the anionic mono nuclear complex [(C(iF5)2Ni(CN) (PPhs)]". Chemical and physical properties of the new isolated complexes are sfudied and structural data are obtained by magnetic suceptibility measurements and IR and visible-UV spectroscopy