Crystal structure and emission spectrum of the undecacoordinate complex tris(nitrato)-1,4,7,10,13-pentaoxacyclopentadecaneeuropium(III)

Abstract

The crystal and molecular structure of tris(nitrato)( 1,4,7,10,13-pentaoxacyclopentadecane)europium(III), Eu(N03),(C,&,05), has been determined from single-crystal X-ray diffraction. The complex crystallizes in the trigonal space group P3] with Z = 3. Lattice parameters are a = 8.845 (3) A, c = 20.330 (4) A, and y = 120O. The structure was solved by Patterson and Fourier techniques and refined by least squares to a final conventional R value of 0.037. The europium(II1) ion is 1 laordinate and bonded to three bidentate nitrate groups and to the five oxygen atoms of the crown ether. The Eu-O(nitrate) and Eu-O(ether) distances lie in the ranges 2.43-2.65 and 2.55-2.69 A, respectively. The nitrate groups are planar with N-0 bond lengths between 1.21 and 1.31 A. The five CHzCH2 moieties of the macrocycle have a slight fluxional motion at room temperature. The coordination polyhedron of the Eu(II1) ion is discussed. The ionic radius of the 1 1-coordinate Eu(II1) ion is 1.25 A. Crystal field splittings, obtained from the high-resolution fluorescence spectrum at 77 K, are reported for the 5D1, 5Dz, 7FI, 7Fz, and 7F4 electronic levels. Interpretation of these splittings leads to the conclusion that the 1 l-coordinate polyhedron of the Eu(II1) ion can be viewed as a distortion of either a pentagonal or a hexagonal symmetry.

Tuning the Polarization Along Linear Polyaromatic Strands for Rationally Inducing Mesomorphism in Lanthanide Nitrate Complexes

“…By using Shannons definition [19] and r(N) = 1.46 , r- [20] we calculate R CN¼10 Eu = 1.187 in 17 and R CN¼9 Yb = 1.044 in 18, in good agreement with related ionic radii reported for the analogous com-…”

Macrocycle complexation chemistry 30: Comparison of the crystal structures of [La(NO3)3(15-crown-5)] and [La(NO3)3(monoaza-15-crown-5)]

“…These are tabulated in Table 2. The values reported for both compounds are significantly different than those reported by Btinzli et al (1982) for [Eu(NO3)3(15-crown-5)]; however, we feel this is primarily due to the severe distortions observed by Btinzli for the carbon atoms.…”

Near-infrared luminescence of Yb3+, Nd3+ and Er3+ in complexes with organic dyes

“…There are two macrocyclic fragments 1,4,7,10-tetraaza-cyclododecane-1,4,7-triacetic acid (DO3A) in ligand L 3 to the contrast of two iminodiacetate groups in ligand PS. The typical changes in the IR spectra of Ln-L 1 and Ln-L 2 complexes are rather similar to those ones for the complexes with benzo-15-crown-5 [12,13]. This fact suggests the coordination of the Ln 3+ ions to five oxygen atoms of the macrocycle and O-atoms of bidentate NO 3 -groups.…”