Macrocyclic structurally reinforced by the inclusion of bridging alkyl groups between nitrogen atoms in the macrocyclic ring. Reinforced macrocycles showed much greater rigidity than those nonreinforced analogueses[1]. The addition of an extra bridging group between nitrogen donors within macrocyclic ligands skeletons (to give a piperazine-like structure) leads to much more rigid ligands displaying selectivity for metal ions due to the match between the size of the metal ion and that of the macrocyclic cavity in comparison with conventional macrocyclic ligands[2]. Two macrocyclic Schiff base ligands (L1, L2) and their related reduced forms (L3 and L4) have been prepared. In the presence of Nickel (II) perchlorate in methanol, the reinforcedmacrobicyclic salts containing hexahydropyrimidine cation moiety have been developed. Here, it seems that Ni (ІІ) perchlorate acts as oxidizing agent converting methanol to the formaldehyde which then, in turn, it bridges two nitrogen atoms of reduced forms of macrocycle producing final products. All Schiff-base ligands and their reduced forms together with related salts were characterized by elemental analysis, IR spectroscopy, 1H and 13C NMR, EI-Mass and in the case of [L3ʹ](ClO4) salt by X-ray crystallography. The proposed mechanism for the formation macrobicycle ligand [L3ʹ] from the reaction of macrocyclic
