Isolation of ternary complex precursors and partially condensed intermediates to macrocyclic complexes of nickel(II) and copper(II)

Reaction in unheated solutions between metal salts, bis(3-aminopropyl)amine (dpt) and 2,6-diacetylpyridine (dap) gives the ternary complexes [M(dpt)(d ap)](2+) - (M = Ni or Cu), in which no Schiff-base condensation has occurre d. Cyclisation requires long standing or heating. For tris(3-aminopropyl)am ine and nickel(II), X-ray crystallography shows that reaction in MeOH can b e stopped after condensation of one carbonyl and one amine group to give a coordinated open-chain hexadentate ligand, an intermediate in the formation of the fully condensed macrocycle. With the 2-(aminoethyl)-4-(butylamino)a mine (ebt), the butylamine groups are involved in intermolecular condensati on with carbonyl groups from adjacent units, giving oligomeric or polymeric complexes.