It is not easy to predict the composition and structure of the final products of a metal promoted or  templated reactions. Even when their composition can be conectly detennined using different reliable ways, the airnngement of the atoms in the resulting products can be obtained using  str11ctural studies. We focussed our investigations on a series of complexes obtained from reactions. a)  a new fainily of manganese(II) coordination compounds with salicyladehyde thiosemicarbazones (H2L) of the general fonnula MnL·3H20 exhibiting dinucleai· structures,[(MnL2)(Mn(H20)4)]-2H20, in which metal ions are in a nonequivalent environment; b) manganese(III) complexes obtained from the recrystallization of the previous MnL·3H20 series from methanol in air, which display a one-dimensional polymer structure [(Mn2L­L)(CH30)2(CH30H)2]n where (H2L-L) is a new ligand generated by manganese-promoted oxidative S-S dimerization of the initial coordinated thiosemicai·bazons. These complexes ai·e the first exainples of manganese(l11) thiosemicarbazone complexes showing single magnet-like prope1iies, i.e. magnetization slow relaxation; c)  Ni(L1 )(PyA) and Mn(L1)(sal) complexes obtained from the reaction of S-alkylated salicylaldehyde thiosemicai·bazone (H2L1) with pyridinealdehyde (PyA) in the presence of Ni(II) or with salicylaldehyde (Hsal) in the presence of Mn(III) metal ions. Using single-crystal X- ray investigation, the fonnation of new tetr·adentate ligands as result of nucleophilic template addition of aldehyde to thiosemicarbazone, has been demonstr·ated; d) palladium complexes with H2L1 ligand that coordinates using ONS donor set and not ONN as for 3d-metal ions. This result shows that palladium ions cannot be used as a templating center for condensation or addition of the second aldehyde molecule. C d Single-crystal X-ray investigation allowed us to access to the precise molecular str11cture of the template reaction products. This knowledge will be fondamental for the optimization of the reaction pathway and more generally will help us as a new analytical tool in a fine organic synthesis.