Crystal and Molecular Structure of the 4:3 Complex between Lanthanum Nitrate and Pentaethyleneglycol Dimethyl Ether |
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Authors: | Jean-Claude C. Bü nzil,Jean-Marc Pfefferl ,Bruno Ammann,Gervais Chapuis,F.-Javier Zuniga |
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Affiliation: | Jean-Claude C. Bünzil,Jean-Marc Pfefferlé,Bruno Ammann,Gervais Chapuis,F.-Javier Zuniga |
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Abstract: | The crystal and molecular structure of [La(NO3)3]4(C12H26O5)3 has been determined from low-temperature single-crystal X-ray diffraction data. The complex crystallizes in the monoclinic space group I2 with Z = 2. Lattice parameters at 150 K are a = 12.234 (6) Å, b = 11.105 (5), c = 26.613 (9), β = 90.65 (4)°. The structure was solved by Patterson and Fourier techniques and refined to a conventional RF-value of 0.068. The compound contains three dinitrato complex cations [La(NO3)2C12H26O6]+ with 10-coordinate lanthanum ions and one hexanitrato anion, [La(NO3)6]3?, with a 12-coordinate La(III)-ion. One complex cation has a C2-symmetry while the two others, which are crystallographically equivalent, have no symmetry and contain a disordered ligand molecule. The polyther adopts a ring-like conformation in all the complex moietis. The La? O(nitrate) distances lie in the ranges 2.52–2.53 and 2.49–2.62 Å, with average values of 2.53 (7) and 2.56 (6) Å, respectively, fo the species with C2- and C1-symmetry; the La? O(ether) bond lengths lie int he range 2.54–2.79 Å (average: 2.6 (1)) for the C2-moiety and their mean value amounts to 2.6 (2) for the disordered species. The hexanitrate has a C2-symmetry and the La? O distances range between 2.56 and 2.67 Å with an average value fo 2.64 (4) Å. The effective ionic radii of the 10- and 12-coordinate La(III) ions are estimated as 1.28 and 1.33 Å, respectively. |
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