Structure and properties of some lanthanoid(III) perchlorate complexes with the crown polyether 5,6,14,15-tetrahydrodibenzo[b,k][1,4,7,10,13,16] hexaoxacyclo-octadecin

Abstract

Some lanthanoid(III) perchlorate complexes with the title ligand (dbc-6) have been prepared in methyl cyanide. Two series have been obtained with formulae Ln[ClO₄]₃.(dbc-6)(Ln = La, Ce, Pr, Nd, Sm, Eu, Dy, or Ho) and Ln[ClO₄]₃.(dbc-6).H₂O (Ln = Er or Yb). The crystal and molecular structure of the [Sm(ClO₄)₃(dbc-6)] complex has been determined from X-ray diffractometric data. Crystals are orthorhombic, space group Fdd2, with a= 37.130(12), b= 12.987(5), c= 11.312(5)Å, and Z= 8. The structure has been refined by least-squares techniques to R 0.047 for 1 115 reflections. The structure shows the samarium(III) ion to be ten-co-ordinated by the six oxygen atoms of dbc-6, by two oxygen atoms of a bidentate [ClO₄]^– ion, and by two oxygen atoms of the other unidentate [ClO₄]^– ions. The complex has C₂ crystallographic symmetry. Conductivity data and i.r. and electronic spectra are discussed. The spectra of the complexes of Sm, Eu, and Yb show electron-transfer transitions in agreement with the optical electronegativity value of 2.7 for the present polyether.