Huh Daniel N, Roy Saswata, Ziller Joseph W, Furche Filipp, Evans William J
Department of Chemistry , University of California , Irvine , California 92697 , United States.
J Am Chem Soc. 2019 Aug 14;141(32):12458-12463. doi: 10.1021/jacs.9b04399. Epub 2019 Jul 31.
Reduction of Th(OCHBu-2,6-Me-4) using either KC or Li in THF forms a new example of a crystallographically characterizable Th(III) complex in the salts [K(THF)(EtO)][Th(OCHBu-2,6-Me-4)] and [Li(THF)][Th(OCHBu-2,6-Me-4)]. Surprisingly, in each structure the four aryloxide ligands are arranged in a square-planar geometry, the first example of this coordination mode for an f element complex. The Th(III) ion and four oxygen donor atoms are coplanar to within 0.05 Å with O-Th-O angles of 89.27(8) to 92.02(8)° between cis ligands. The ligands have Th-O-C(ipso) angles of 173.9(2) to 178.6(4)°, and the aryl rings make angles of 58.5 to 65.1° with the ThO plane. The effect of the eight -butyl substituents in generating the unusual structure through packing and/or dispersion forces is discussed. EPR spectroscopy reveals an axial signal consistent with a metal-based radical in a planar complex. DFT calculations yield a -symmetric structure that accommodates a low-lying SOMO of 6d character with 7s Rydberg admixture.
在四氢呋喃（THF）中使用钾（KC）或锂还原Th(OCHBu-2,6-Me-4)，在盐[K(THF)(EtO)][Th(OCHBu-2,6-Me-4)]和[Li(THF)][Th(OCHBu-2,6-Me-4)]中形成了一个新的可通过晶体学表征的Th(III)配合物实例。令人惊讶的是，在每个结构中，四个芳氧基配体以平面正方形几何结构排列，这是f元素配合物这种配位模式的首个实例。Th(III)离子和四个氧供体原子共面，平面度在0.05 Å以内，顺式配体之间的O-Th-O角为89.27(8)至92.02(8)°。配体的Th-O-C(ipso)角为173.9(2)至178.6(4)°，芳环与ThO平面的夹角为58.5至65.1°。讨论了八个叔丁基取代基通过堆积和/或色散力产生异常结构的影响。电子顺磁共振（EPR）光谱显示出一个轴向信号，与平面配合物中基于金属的自由基一致。密度泛函理论（DFT）计算得出一种对称结构，该结构容纳一个具有6d特征且有7s里德堡混合的低能级单占据分子轨道（SOMO）。
