Expanding Rare-Earth Oxidation State Chemistry to Molecular Complexes of Holmium(II) and Erbium(II)
| Autor: | Megan E. Fieser, Joseph W. Ziller, Filipp Furche, Matthew R. MacDonald, Jefferson E. Bates, William J. Evans |
|---|---|
| Rok vydání: | 2012 |
| Předmět: |
Inorganic chemistry
chemistry.chemical_element General Chemistry Ring (chemistry) Biochemistry Catalysis law.invention Metal chemistry.chemical_compound Crystallography Colloid and Surface Chemistry chemistry Oxidation state law visual_art visual_art.visual_art_medium Density functional theory Electron configuration Crystallization Holmium 2.2.2-Cryptand |
| Zdroj: | Journal of the American Chemical Society. 134:8420-8423 |
| ISSN: | 1520-5126 0002-7863 |
| Popis: | The first molecular complexes of holmium and erbium in the +2 oxidation state have been generated by reducing Cp'(3)Ln [Cp' = C(5)H(4)SiMe(3); Ln = Ho (1), Er (2)] with KC(8) in the presence of 18-crown-6 in Et(2)O at -35 °C under argon. Purification and crystallization below -35 °C gave isomorphous [(18-crown-6)K][Cp'(3)Ln] [Ln = Ho (3), Er (4)]. The three Cp' ring centroids define a trigonal-planar geometry around each metal ion that is not perturbed by the location of the potassium crown cation near one ring with K-C(Cp') distances of 3.053(8)-3.078(2) Å. The metrical parameters of the three rings are indistinguishable within the error limits. In contrast to Ln(2+) complexes of Eu, Yb, Sm, Tm, Dy, and Nd, 3 and 4 have average Ln-(Cp' ring centroid) distances only 0.029 and 0.021 Å longer than those of the Ln(3+) analogues 1 and 2, a result similar to that previously reported for the 4d(1) Y(2+) complex [(18-crown-6)K][Cp'(3)Y] (5) and the 5d(1) La(2+) complex [K(18-crown-6)(Et(2)O)][Cp″(3)La] [Cp″ = 1,3-(Me(3)Si)(2)C(5)H(3)]. Surprisingly, the UV-vis spectra of 3 and 4 are also very similar to that of 5 with two broad absorptions in the visible region, suggesting that 3-5 have similar electron configurations. Density functional theory calculations on the Ho(2+) and Er(2+) species yielded HOMOs that are largely 5d(z(2)) in character and supportive of 4f(10)5d(1) and 4f(11)5d(1) ground-state configurations, respectively. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|