title: Lanthanide complexes derived from hexadentate macrocyclic ligand: synthesis, spectroscopic and thermal investigation.
abstract: The lanthanide complexes derived from (3,5,13,15-tetramethyl 2,6,12,16,21-22-hexaazatricyclo[15.3.I(1-17)I(7-11)]cosa-1(21),2,5,7,9,11(22),12,15,17,19-decane) were synthesized. The complexes were found to have general composition [Ln(L)X(2).H(2)O]X, where Ln=La(3+), Ce(3+), Nd(3+), Sm(3+) and Eu(3+) and X=NO(3)(-) and Cl(-). The ligand was characterized by elemental analyses, IR, Mass, and (1)H NMR spectral studies. All the complexes were characterized by elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, Mass, electronic spectral techniques and thermal studies. The ligand acts as a hexadentate and coordinates through four nitrogen atoms of azomethine groups and two nitrogen of pyridine ring. The lanthanum complexes are diamagnetic while the other Ln(III) complexes are paramagnetic. The spectral parameters i.e. nephelauxetic ratio (beta), covalency factor (b(1/2)), Sinha parameter (delta%) and covalency angular overlap parameter (eta) have been calculated from absorption spectra of Nd(III) and Sm(III) complexes. These parameters suggest the metal-ligand covalent bonding. In the present study, the complexes were found to have coordination number nine.
authors.affiliation: Department of Chemistry, Zakir Husain College, University of Delhi, JL Nehru Marg, New Delhi 110002, India. schandra_00@yahoo.com
authors.forename: Sulekh
authors.initials: S
authors.lastname: Chandra
authors.forename: Monika
authors.initials: M
authors.lastname: Tyagi
authors.forename: Soni
authors.initials: S
authors.lastname: Rani
authors.forename: Sumit
authors.initials: S
authors.lastname: Kumar
mesh_terms: D028581:Lanthanoid Series Elements / Q000138:chemical synthesis* / Q000737:chemistry* / Q000378:metabolism; D008024:Ligands; D047028:Macrocyclic Compounds / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D019216:Metals, Heavy / Q000737:chemistry; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D021241:Spectrometry, Mass, Electrospray Ionization; D013055:Spectrophotometry, Infrared
chemical_list: D028581:Lanthanoid Series Elements; D008024:Ligands; D047028:Macrocyclic Compounds; D019216:Metals, Heavy