Reaction of 5,6-dihydro-5,6-epoxy-1,10-phenanthroline (L) with Ni(ClO 4 ) 2 ·6H 2 O in methanol in 3:1M proportion at room temperature yields [NiL 3 ](ClO 4 ) 2 ·2H 2 O. The X-ray crystal structure of the cation NiL32+ has been determined. Aminolysis of the three epoxide rings in NiL32+ by 4-substituted anilines in boiling water without any Lewis acid catalyst gives a family of Ni(II) complexes with octahedral NiL62+ core. In these complexes, crystal field splitting 10Dq varies from 11601 to 15798cm −1 in acetonitrile. The variation in 10Dq is found to be satisfactorily linear (r 2 =0.951) with the Hammett σ R parameter of the substituent on the anilino fragment. 10Dq increases with the increase in the electron donation ability of the substituent.