Synthesis and characterization of samarium(III) complexes with piperidin-4-ones

Ten samarium nitrate complexes with variously substituted 2,6-diphenylpiperidin-4-ones (L-1)-(L-10) have been prepared in ethanol. These complexes with the general formula [Sm(L)NO3)(2)(H2O)(2)]NO3. H2O have been characterized by elemental analysis, molar conducatance, magnetic and thermal studies, infrared, electronic and NMR spectra. Molar conductance data show that these complexes are 1:1 electrolytes. The IR spectral data reveal the participation of water molecules and thermal studies confirm the presence of one lattice-held water molecule and two coordinated water molecules, IR spectra, elemental analyses and molar conductance data suggest that these complexes contain one ionic and two bidentate nitrate groups. Although piperidin-4-ones have two coordinating sites, namely the ring nitrogen and carbonyl group, IR and NMR spectral evidence is in favour of the ring nitrogen as the coordinating group and not the carbonyl group, thereby indicating that these ligands are monodendate. All the observations lead to the conclusion that the samarium has a coordination number of seven in these complexes.