The reactions of nickelocene with pyrazoles in benzene solution have resulted in the isolation of either dimeric compounds, [CpNi(μ-pz′)]2, (room temperature conditions) or trimetallic complexes, [CpNi(μ-pz″)2]2Ni, (elevated temperature conditions). Both dimeric and trimetallic species were obtained as red crystalline materials and X-ray structural investigations are reported for representative samples of each type. Structural features are interpreted and compared with similar, previously reported, nickel pyrazolate structures. Crystals of [CpNi(3,5-diMepz)]2(C20H24N4Ni2),1, are orthorhombic,a = 15.204(1),b = 17.967(2),c = 6.9786(9) Å,Z = 4, space groupAma2; those of [CpNi(4-NO2-3,5-diMepz)]2(C20H22N6Ni2O2),5, are orthorhombic,a = 17.145(3),b = 17.738(1),c = 7.006(1) Å,Z = 4, space groupP212121; those of [CpNi(3,5-F6diMepz)]2(C20H12F12N4Ni2),6, are orthorhombic,a = 18.7134(8),b = 15.619(2),c = 7.7263(9) Å,Z = 4, space groupPnma; those of [CpNi(3,5-diMepz)2]2Ni (C30H38N8Ni3),7, are triclinic,a = 10.078(2),b = 16.134(2),c = 9.992(1) Å, α = 91.586(10)°, β = 111.050(9)°, γ = 86.95(1)°,Z = 2, space group; and those of [CpNi(4-Cl-3,5-diMepz)2]2Ni (C30H34Cl4N8Ni3),10, are monoclinic,a = 10.2201(7),b = 16.174(1),c = 10.7207(9) Å, β = 108.193(5)°,Z = 2, space groupP21/a. The structures were solved by direct (dimetallic species) or Patterson (trimetallic complexes) methods and were refined by full-matrix least-squares procedures toR = 0.035, 0.032, 0.058, 0.032, and 0.033 (Rw = 0.021, 0.026, 0.053, 0.028, and 0.032) for 1157, 1894, 1642, 4499, and 2113 reflections withI ≥ 3σ(F2), respectively.Keywords: crystal structures, nickel, nickelocene, pyrazolates, cyclopentadienyl.