The preparation of a series of novel compounds of general formula [Ni5L4(NO2)8(OH)2] formed by ethane-l, 2-diamine or one of five N-substituted ethane-1, 2-diamines (L) is described. The crystal and molecular structures of the ethane-1, 2-diamine, N, N′-diethylethane-l, 2-diamine and N, N-dimethylethane-l, 2-diamine complexes are reported. Each compound contains a planar, pentameric arrangement of nickel(II) ions, linked by bridging hydroxide and nitrite ligands. The details of the nitrite bridges differ among the complexes, causing differences in their electronic and infrared spectra. The structural variations are probably caused by the differing steric requirements of the amine substituents.