Studies on cerium(III) complexes of piperidin-4-ones

Abstract

Ten new cerium (III) nitrate complexes of the general formula

[Ce(L)₂(NO₃)₂(H₂O)₂]NO₃ with variously substituted 2,6-diphenylpiperidin-4-ones (L¹)-(L¹⁰) have been prepared in ethanol and characterized by elemental analysis, molecular weights, molar conductance, magnetic and thermal studies and infrared and NMR spectra. Molar conductance data and van't Hoff factor (i = 2) 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 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 evidences are 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 cerium has a coordination number of eight in these complexes.