The nickel coordination chemistry of a series of polytopic diazine (N-N) based ligands has been examined. Self-assembly reactions lead to examples of dinuclear, trinuclear, tetranuclear, pentanuclear, and octanuclear, complexes, all of which exhibit magnetic exchange coupling, with antiferromagnetic and ferromagnetic examples. Structural details are presented for [(L1)(2)Ni-2(H2O)(2)](NO3)(4).3H(2)O (1), [(L2)(2)Ni-3(H2O)(2)](NO3)(6).8H(2)O (2), [(L3)(4)Ni-4(H2O)(8)] (NO3)(4).8H(2)O (3), [(L4)(2)Ni-5(H2O)(10)(NO3)](NO3)(7).8H(2)O (4), and [(L5)(4)Ni-8(H2O)(8)](BF4)(8).16H(2)O (5). Compound 1 crystallizes in the monoclinic system, space group P2(1/C1), with a = 14.937(1) Angstrom, b = 18.612(2) Angstrom, c = 20.583(2) , beta = 108.862-(2)degrees, Z = 4. Compound 2 crystallizes in the orthorhombic system, space group P2(1)2(1)2, with a = 21.771(4) Angstrom, b = 13.700(2) Angstrom, c = 20.017(3) Angstrom, Z = 4. Compound 3 crystallizes in the tetragonal system, space group P4(3), with a = 12.9483(7) Angstrom, c = 33.416(3) Angstrom, Z = 4. Compound 4 crystallizes in the triclinic system, space group P1, with a = 12.6677(8) Angstrom, b = 18.110(1) Angstrom, c =19.998(1) Angstrom, alpha = 100.395(1)degrees, beta = 109.514(1)degrees, gamma = 109.686(1)degrees, Z = 2. Compound 5 crystallizes in the monoclinic system, space group P2(1/n), with a = 21.153(5) Angstrom, b = 35.778(9) Angstrom, c = 21.823(5) Angstrom, beta = 97.757(6)degrees, Z = 4. The linear trinuclear Ni(II) complex (2) has a cis-N-N single bond bridge, and a water bridge linking the central Ni(II) to each external Ni(II) center in each of two similar trinuclear subunits, and exhitibs intramolecular ferromagnetic exchange (J = 5.0 cm(-1)). A novel octanuclear metallycyclic ring structure exists in 5, with trans-N-N single bond bridges linking adjacent Ni(II) centers, leading to quite strong intramolecular antiferromagnetic exchange (J = -30.4 cm(-1)).