Syntheses, structures, and spectroscopy of mono- and polynuclear lanthanide complexes containing 4-acyl-pyrazolones and diphosphineoxide

Lanthanide coordination compounds are important due to their unique luminescence and magnetic properties. Direct synthesis of oligo- and polymeric Ln complexes with a predicted structure is hampered due to high coordination numbers and unstable coordination polyhedra. A building blocks strategy for the synthesis of Ln(Q)(3)L polymers (Ln = Eu, Tb or Gd; HQ = 1-phenyl-3-methyl-4-RC(=O)pyrazol-5-one in general, in detail HQ(S), R = thienyl; HQ(CP): R = cyclopentyl; L = bis(diphenylphosphine) methane dioxide dppMO(2), bis(diphenylphosphine) ethane dioxide dppEO(2), and bis(diphenylphosphine) butane dioxide dppBO(2)) has been used: {Ln(Q)(3)} mononuclear fragments have been linked by dppXO(2) bridges when X = E or B, while monomeric molecular derivatives have been isolated with dppMO(2). Eighteen new complexes were prepared, 12 of them showing a polymeric nature and 6 being monomers. Three compounds have been structurally characterized, further confirming the hypothesized connectivity where metal centers have been found to exist in LnO(8) square antiprismatic environments. Luminescence properties have been also investigated. (C) 2010 Elsevier B.V. All rights reserved.