Bis(cyclo-octa-1,5-diene)nickel reacts with perfluoropropene to give (1,5-C8H12)Ni(C3F6)(I), which reacts with triphenyl- or triethyl-phosphine to afford (Ph3P)2Ni(C3F6)(IIa) and (Et3P)2Ni(C3F6)(IIb), respectively. The zerovalent nickel compounds (1,5-C8H12)(Et3P)2Ni, (1,5-C8H12)[(Bun)3P]2Ni, [(Ph2PCH2)2][(Bun)3P]2Ni, (Et3P)4Ni, and (Ph2PMe)4Ni, react with tetrafluoroethylene to give the stable crystalline octafluoronickelacyclopentane complexes L2Ni(CF2)4(L = Et3P, Bun3P, or Ph2PMe; or L2= Ph2PCH2CH2PPh2). These complexes readily undergo ligand-exchange reactions, and by treatment with 2,2′-bipyridyl or cyclo-octa-1,5-diene and zinc bromide give, in certain cases, the crystalline derivatives C10H8N2Ni(CF2)4(VIII) and (1,5-C8H12)Ni(CF2)4(IX). The diene ligand in the latter can be displaced with triphenylphosphine or γ-picoline to give (Ph3P)2Ni(CF2)4 and (γ-picoline)2Ni(CF2)4, respectively. Treatment of (1,5-C8H12)2Ni with C2F4 gives an unstable compound, which on addition of Ph2PMe or Et3P gave L2Ni(CF2)4. The compound [(MeO)3P]2Ni(CF2)4,½C6H6 is obtained from tetrafluoroethylene and tetrakis(trimethyl phosphite)nickel, and tetrakis(methyldiphenylphosphine)nickel reacts with trifluoroethylene to give (Ph2PMe)2Ni(C2F3H)2.