Synthesis and characterization of mono and trinuclear lanthanide (III) complexes of 12-membered tetraaza macrocycle

Abstract

The reaction of triethylene tetraamine and diethyl oxalate yield a 12-membered macrocycle. The complexes [Ln(tadd)Cl₂(H₂O)₂]Cl (Ln(III) = La, Pr, Nd, Sm, Eu, Gd, Tb and Dy; tadd = 1,4,7,10-tetraazacyclo dodecane-2, 3-dione) have been synthesized by template reaction of the lanthanide ion. The complex [La(tadd)Cl₂ (H₂O)₂]Cl reacts with lanthanide chlorides to yield the complexes of type [2{La(tadd)Cl₂ (H₂O)₂}LnCl₃(H₂O)₂]Cl₂. The chemical  compositions of  both the mono and trimetallic complexes have been established from analytical, molar conductance and FAB mass data. It is observed that the macrocycle is bonded in tetrakis fashion in the former complexes and hexakis in the latter. The

<span style="font-size:12.0pt;font-family:" times="" new="" roman","serif";mso-fareast-font-family:="" calibri;mso-fareast-theme-font:minor-latin;color:#454545;mso-ansi-language:="" en-in;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">co<span style="font-size:12.0pt;font-family:" times="" new="" roman","serif";mso-fareast-font-family:="" calibri;mso-fareast-theme-font:minor-latin;mso-ansi-language:en-in;mso-fareast-language:="" en-us;mso-bidi-language:ar-sa"="">ordination number eight around the encapsulated metal ions and nine around the exocyclic oxygen bonded metal ions are established from IR and electronic spectra. The symmetry of the ligand field around the metal ions is indicated from the emission spectra.</span></span>