Rare-Earth Metal(II) Aryloxides: Structure, Synthesis, and EPR Spectroscopy of [K(2.2.2-cryptand)][Sc(OC6 H2 tBu2 -2,6-Me-4)3 ].
Rare-Earth Metal(II) Aryloxides: Structure, Synthesis, and EPR Spectroscopy of [K(2.2.2-cryptand)][Sc(OC6 H2 tBu2 -2,6-Me-4)3 ].
复制标题
稀土金属 (II) 芳基氧化物：[K(2.2.2-cryptand)][Sc(OC6 H2 tBu2 -2,6-Me-4)3 ] 的结构、合成和 EPR 光谱。
作者：
S. Moehring;María J Beltrán;D. Páez‐Hernández;R. Arratia‐Pérez;J. Ziller;W. Evans
芳氧基配体的稳定+2氧化态的Sc和Y的适用性已被检查和EPR证据表明，第一O-供体配合物的ScII和YII已获得，以及X-射线晶体结构的ScII芳氧基配合物。以三氯化稀土金属和LiOAr ′-OEt ′ 2为原料，合成了三价稀土金属芳基氧化物前体Ln（OAr ′）3，1-Ln（Ln=Sc，Y，Gd，Dy，Ho，Er; OAr ′ = OC 6 H2 tBu 2 - 2，6-Me-4）。在2.2.2-穴状配体（crypt）存在下，用钾石墨还原1-Ln的THF溶液，得到深色溶液2-Ln，其在77 K下的EPR光谱是Ln II离子的特征：2-Y的双线光谱（g λ =1.99，g□ =1.97，Aave =154 G）和2-Sc的八线光谱（g λ =2.01，Aave =291 G）。2-Y溶液在室温下在1分钟内分解，而2-Sc在室温下持续长达40分钟。 2-Sc通过X射线晶体学鉴定为[K（crypt）][Sc（OAr '）3 ]，其具有围绕ScII的氧供体原子的三角平面排列。类似的减少1-Ln的Ln=Gd，Dy，Ho，和Er也给出了有限的稳定性的黑暗的解决方案。理论分析采用含时密度泛函理论（TD-DFT）沿着与完全活性空间自洽场（CASSCF）方法，和结构分析与Guzei配体立体角G参数方法。
The suitability of aryloxide ligands for stabilizing +2 oxidation states of Sc and Y has been examined and EPR evidence indicating the first O-donor complexes of ScII and YII has been obtained, as well as an X-ray crystal structure of a ScII aryloxide complex. The trivalent rare-earth metal aryloxide precursors, Ln(OAr')3 , 1-Ln (Ln=Sc, Y, Gd, Dy, Ho, Er; OAr'=OC6 H2 tBu2 -2,6-Me-4), were synthesized from the corresponding rare-earth metal trichlorides and LiOAr'⋅OEt2 . Reduction of THF solutions of 1-Ln with potassium graphite in the presence of 2.2.2-cryptand (crypt) yielded dark-colored solutions, 2-Ln, whose EPR spectra at 77 K are characteristic of the LnII ions: a two-line spectrum (g∥ =1.99, g□ =1.97, Aave =154 G) for 2-Y and an eight-line spectrum (gave =2.01 and Aave =291 G) for 2-Sc. Solutions of 2-Y decompose within one minute at room temperature, wheras 2-Sc persists up to 40 min at room temperature. 2-Sc was identified by X-ray crystallography as [K(crypt)][Sc(OAr')3 ], which has a trigonal-planar arrangement of oxygen-donor atoms around ScII . Analogous reductions of 1-Ln for Ln=Gd, Dy, Ho, and Er also gave dark solutions of limited stability. Theoretical analysis using time-dependent density functional theory (TD-DFT) along with complete active space self-consistent field (CASSCF) methods, and structural analysis with the Guzei ligand solid angle G-parameter method are presented.