2,4-Lutidine-1-oxide (2,4-LutO) complexes of lanthanide perchlorates of the formulae Ln₂(2,4-LutO)₁₃(ClO₄)₆ (Ln = Pr and Nd) and Ln₂(2,4-LutO)₁₅ (ClO₄)₆ (Ln = La, Tb, Dy, Ho and Yb) have been prepared and characterised by chemical analysis, IR, NMR, conductance and electronic spectral data. Proton NMR data along with the IR data show that the ligand coordinates to the metal ion through the oxygen. Conductance data of the complexes in acetone and nitrobenzene indicate that the perchlorate is not coordinated to the metal ion.

Adducts of lanthanide perchlorates with 4-nitro and 4-chloro pyridine-Noxides (4-NPNO and 4-CPNO respectively) have been synthesised for the first time and characterised by analysis, electrolytic conductance, infrared, proton-NMR and electronic spectral data. The complexes are of the compositions Ln₂(NPNO)₁₅ (ClO₄)₆ (Ln = La, Pr, Nd and Gd), Tb(NPNO), (C1O₄)₆), Ln₂(NPNO)₁₃ (C1O₄)₆) (Ln = Dy, Ho, and Yb); Ln (CPNO)₈ (C10₄)₃) (Ln = La, Pr, Nd, Tb, Dy, Ho and Yb) and Ln(CPNO), (C1O₄)₃) (Ln = Sm and Gd). Conductivity and IR data provide evidence for the non-coordinated nature of the perchlorate groups. IR and NMR spectra suggest coordinationvia the oxygen of the N-oxide group. Electronic spectral shapes of the Nd⁺³ and Ho⁺³ complexes are interpreted in terms of eight-and seven-coordinate environments in the case of 4-NPNO complexes and eight-coordination in the case of 4-CPNO complexes. IR data indicate bridged structure in NPNO complexes of lanthanides other than Tb.

4-Nitro 2-picoline-l-oxide (NPicO) complexes of the formulae La (NPicO)₅ (CIO₄)₃, Ln₂ (NPicO)₉ (C1O₄)₆ (Ln = Pr, Nd, and Gd) and Ln (NPicO)₄ (CIO₄)₃ (Ln == Tb, Dy, Ho and Yb) have been synthesised and characterised by analysis, electrolytic conductance, infrared, proton NMR and electronic spectral data. A tentative coordination number of 6 for all the complexes have been assigned

New complexes of lanthanide nitrates with 2-N-(6-picolyl)-benzamide of the formulae Ln₂[6-pic-BA], [NO₃l₆ (Ln = Y and La-Yb) have been prepared and characterised by chemical analysis, infrared, molar conductance and electronic spectral data. Molar conductance data along with IR data point to the presence of co-ordinated nitrate groups. IR spectra prove the bidentate co-ordination of the ligand to the metal ion, through the oxygen of the secondary amide and the nitrogen of the heterocyclic ring. Electronic spectral studies in the visible region suggest an eight co-ordinate geometry around the metal ions.

New complexes of lanthanide perchlorates with di-t-butyl amides of di, tri and tetraglycolic acids have been synthesised. The complexes have the general formula Ln(DiGA)₃(ClO₄)₃; Ln(TriGA)₂ (ClO₄)₃ and Ln(TetGA)₂ (C1O₄)₃, where Ln = La-Yb and Y and DiGA = N,N′, di-t-butyl diglycolamide, TriGA N,N′, di-t-butyl triglycolamide and TetGA = N,N′ di-t-butyl tetraglycolamide, respectively. The complexes have been characterized by analysis, electrolytic conductance, infrared,¹H and¹³C nuclear magnetic resonance and electronic spectral data.

Infrared spectra indicate the coordination of all the available ether oxygens and the amide carbonyls in each of the ligands, to the metal ions. IR and conductance data show that the perchlorate groups in all the complexes are ionic.¹H and¹³C NMR data support the IR data regarding the mode of coordination of ligands to the metal ions. Electronic spectral shapes have been interpreted in terms of nine, eight and ten coordination in DiGA, TriGA and TetGA complexes respectively.

2,6-Lutidine-N-oxide (LNO) complexes of rare-earth bromides of the composition$$MBr_3 .(LNO)_{4_{ - n} } .nH_2 O$$ wheren = l for M = La, Pr, Nd, Sm, Gd, Ho, Er; andn = 0 for M = Y have been prepared and characterised by analyses, conductance and infrared data. Infrared spectra of the complexes indicate that the coordination of ligand to the metal ion takes place through the oxygen of the ligand, and the water molecule in the complexes present is coordinated to the metal. A coordination number of seven has been suggested to all the rare-earth metal ions.

New complexes of lanthanide nitrates with N, N-diethylantipyrine-4-carboxamide (DEAP), with the general formulae [Ln₂(DEAP)₃] [NO₃]₆ (where Ln = La, Pr, Nd, Sm, Tb, Ho, Er, Yb and Y) have been isolated and characterized by chemical analysis and various physical methods such as electrolytic conductance, IR and¹³C NMR spectral data. Electrolytic conductance values and infrared spectral studies indicate that the nitrate groups are coordinated. Infrared and¹³C NMR spectral analysis show that the ligand DEAP is coordinated to the tripositive metal ion through the diethylcarboxamide carbonyl and antipyrine carbonyl oxygens in a bidentate fashion.