The imidazole- and pyrazole-functionalised macrocyclic ligands 1,4,7-tris(1-methylimidazol-2-ylmethyl)-1,4,7-triazacyclononane, L¹, and 1,4,7-tris(pyrazol-1-ylmethyl)-1,4,7-triazacyclononane, L², form stable complexes with some 3d metal cations of formula [ML]Y₂(M = Fe, L = L¹ or L², Y = BPh₄; M = Co, L = L¹, Y = ClO₄; L = L², Y = BPh₄; M = Ni, L = L¹, Y = BPh₄ or ClO₄; L = L², Y = BPh₄; M = Cu, L = L¹, Y = BPh₄; L = L², Y = ClO₄; M = Zn, L = L², Y = BPh₄). The complexes have been isolated in the solid state and characterised by standard physicochemical methods. The complex [NiL²][BPh₄]₂ affords by slow recrystallisation from an acetonitrile—ethanol solution the new compound [Ni(CH₃CN)L³][BPh₄]₂ where L³ is the new ligand 1,4-bis(pyrazol-1-ylmethyl)-1,4,7-triazacyclononane formed from L² by a N-dealkylation reaction and loss of a pendant arm. Its crystal structure has been determined by X-ray diffraction: space group P2₁/c, a= 18.544(12), b= 12.460(5), c= 23.400(9)Å, β= 90.49(4)°; R 0.069 for 3025 observed reflections. The nickel atom is in a six-co-ordinate environment formed by the five nitrogen atoms provided by the L³ ligand and by the acetonitrile N atom. All Ni–N distances are in the range 2.00–2.11 Å, those formed by the macrocycle nitrogens spanning the upper half of this interval.