Two ONNO type naphtaldehyde derivative Schiff base compounds were reduced and two symmetric phenol-amine ligands containing naphthalene groups were obtained; bis-N,N'[(2-hydroxy-1-naphtyl) methyl]-1,3-propanediamine (NAFL(H)) and bis-N,N'[(2-hydroxy-1-naphtyl) methyl]-2,2'-dimetyhyl-1,3-propanediamine (NAFLDM(H)). Homotrinuclear Ni(II) complexes of these ligands were prepared. The solid-state molecular structures of representative nickel complex of NAFLDM(H) were determined using single crystal X-ray diffraction analysis. The terminal Ni(II) ions were found to be situated in between the donor atoms of the organic ligand. The central Ni(II) ion was observed to be bonded via two different mu-bridges. The phenolic oxygens and carboxylate ion were seen to form two different mu-bridges. TG analysis proved that the compounds have different thermal characteristics than those cited in literature. The complexes showed extreme exothermic degradation reactions in inert atmosphere. The complexes are ruptured with a two stepped exothermic reaction which appears huge heat over 300 A degrees C. The heat appeared in O-2 atmosphere is observed to be higher than the heat appeared in inert atmosphere. Revealed heat is observed to be higher than the conventional explosive materials.