Abstract: Two solid complexes of cerium(Ⅳ) salts with 1,10-Phenanthrolinc-1-oxide(o-phcnNO) were preparcd and characterized, having the composition of Ce(po-henNO) (NO₃)₃(OH). H₂O and Ce(o-PhenNO)₄(NO₃)(ClO₄)₃·H₂O. IR spectra indicate that the characteristic frequencies assignable to stretching vibration of Ce-O(o-phenNO)bond in these complexes appear in the region of 385-390cm^-1Vci-(NO-phenNO) in the region of 255-260cm^-1, V_N→o and O_N-→o of free ligand shift to lower wave numbers upon complexation, The molar conductance and IR spectra data show that NO₃-and CIO₄^- are not coordinated in Ce(oPhenNO)₄ (NO₃)(CIO₄)₃·H₂O, and all NO₃^- are coordinated in Ce(c-PhenNO)(NO₃)₃ (OH), H₂O, The UV spectrum of Ce(o-PhenNO)₄(NO₃)(CIO₄)₃. H₂O is similar to that of the free ligand. The complexes are less soluble in some organic solvents than the ligand.

Key words: Cerium, 1,10-phenanthroline-l-oxide, Complex