Syntheses, characterisation, magnetism and photoluminescence of a homodinuclear Ln(III)-Schiff base family

A novel family of homodinuclear complexes of the general formula [Ln(2)L(2)(X)(2)] (where Ln = Nd3+, Pr3+, Sm3+ and Tb3+ for 1, 2, 3 and 4, respectively and X, the coordinated NO3- or Cl- anion) has been synthesised from the corresponding lanthanide(III) salts with the pentadentate dianionic Schiff base ligand, H2L [N-1,N-3-bis(salicylideneimino)diethylenetriamine], that exhibits a N3O2 donor set. Single crystal X-ray diffraction studies evidenced the isostructurality of this family of centrosymmetric neutral dinuclear entities where the Ln(III) metal centres are coupled together by two phenolato oxygen atoms belonging to two units of ligand (H2L). Interestingly, the two other phenolato groups of H2L are mono-coordinated to the metal ions. Temperature dependence (2-300K) magnetic susceptibility studies suggest the presence of an antiferromagnetic interaction operating via double phenolato bridges. Photoluminescence activities of the complexes have been studied and compared with their precursor ligand. All the complexes have been characterised with microanalytical and several spectroscopic techniques.