A novel (EE)-dioxime,5,6:13,14-di(4'-t-butylbenzo)-2,3-bis(hydroxyimino)-8,11-dithia-1,4-diazacyclotetradecane (H2L), containing a 14-membered dithiadiaza macrocyclic unit has been synthesized by the reaction of 1,2-bis(4-t-butyl-2-aminobenzylthio)ethane (1) and cyanogendi-N-oxide (2). A mononuclear nickel(II) complex (3) with a metal : ligand ratio of 1 : 2 was also prepared. A heterotrinuclear complex [Cu2Ni(HL)(2)](PF6)(2) (4) was synthesized by using the mononuclear complex 3 and [Cu(CH3CN)(4)]PF6. A heteropentanuclear complex (Cu-2(UO2)(2)(phen)(2)Ni(HL)(2)](PF6)(2)(NO3)(2) (5) containing the oximato tetraanion as a bridging ligand and 1,10-phenanthroline as an end-capping ligand was obtained by using the heterotrinuclear ligand for the Cu2Ni(HL)(2)(n+) center. The ligand and its complexes have been characterized by H-1 and C-13 NMR, IR and mass spectroscopy, elemental analysis and semiempirical quantum chemical calculations.