Résumé

The crystal and molecular structure of dinitrato(1,7,10,16‐tetraoxa‐4,13‐diazacyclooctadecane)europium(III) nitrate, ([Eu(NO3)2(C12H26N2O4)]NO3) has been determined from single‐crystal X‐ ray diffraction: a = 12.567(3), b = 11.585(3), c = 16.354(5) Å, β = 112.45(2)°, space group P 21/n , Z = 4. The structure consists of discrete dinitrato complex cations and of nitrate anions. The Eu(III) ion is 10‐coordinate, bonding to the six donor atoms of the macrocycle and to four O‐atoms of the two bidentate nitrates. The mean distances are Eu-O(ether) = 2.60(2), Eu-O(NO3) = 2.47(3) and Eu-N = 2.62(2) Å. The metal site has an approximate C 2 symmetry. The IR and Raman spectra show the presence of an ionic and of two bonded bidentate nitrates. These latter have a different v1‐v 4 splitting, which reflects their dissymmetrical bonding. Luminescence spectra have been recorded at 296, 77, and 4 K by laser‐excitation techniques. One sharp 5D0←7F0 transition was observed and almost all the sublevels of the 7FJ manifold could be identified. The interaction between a sharp distribution of the phonon states (especially between 950 and 1200 cm−1) and the electronic 7F2 sublevels results in the presence of several satellite lines accompanying the 5D0→7F2 transition. In MeCN solutions, both luminescence and conductivity data point to the presence of the [Eu(NO3)2(2,2)]+ cation.

Détails

Actions