Wydział Chemii

Anna Mondry

Przemysław Starynowicz

2006

European Journal of Inorganic Chemistry

1859-1867

10.1002/ejic.200501023

Naukowa

Angielski

Artykuł

The crystal structures and spectroscopic (IR, Raman, UV/Vis) data for the complexes [C(NH₂)₃]₂[Nd(HTTHA)]·3H₂O (I) and [C(NH₂)₃]₃[Nd(TTHA)]·6H₂O (II) are presented. Crystals of I are triclinic, P, a = 9.998(2), b = 10.730(2), c = 15.557(3) Å, α = 106.89(3)°, β = 90.27(3)°, γ = 93.24(3)°, V = 1594.0(5) ų, Z = 2, while the chiral crystals of II are monoclinic, P2₁, a = 10.157(2), b = 15.958(3), c = 12.788(3) Å, β = 112.68(3)°, V = 1912.5(7) ų, Z = 2. Both structures consist of the complex monomeric anions, guanidinium cations and water of hydration. The Nd^III ions are ten-coordinate. The TTHA ligand coordinates to the Nd^III ions with six of its carboxyl oxygen atoms and four nitrogen atoms. Although the coordination environments of both Nd^III cations are essentially the same, the spectral results of both crystals reveal the influence of the degree of protonation of the ligand on the Nd^III ion. The IR and Raman spectra allowed us to assign some important frequencies. A comparison of the electronic absorption spectra of Nd^III–TTHA complexes in solution and in single crystals of I and II allows the detection of a small elongation of the Nd–O and Nd–N bonds in these complexes as compared to the [Nd(TTHA)]^3– moiety in the previously reported complex Na₃[Nd(TTHA)]·2.5NaClO₄·7.617H₂O and indicates that the coordination geometry of the ten-coordinate neodymium complex in solution is the same as in the chiral crystal II. The intensities of the f–f transitions in Nd^III–TTHA solutions and of crystals I and II were analysed on the basis of the Judd–Ofelt theory.

https://doi.org/10.1002/ejic.200501023

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