Sergentu Dumitru-Claudiu, Kent Greggory T, Staun Selena L, Yu Xiaojuan, Cho Herman, Autschbach Jochen, Hayton Trevor W
Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, United States.
Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States.
Inorg Chem. 2020 Jul 20;59(14):10138-10145. doi: 10.1021/acs.inorgchem.0c01263. Epub 2020 Jun 28.
The solid-state N NMR powder spectra of the thorium nitride complex, [K(18-crown-6)(THF)][(RN)Th(μ-N)Th(NR)] (, R = SiMe), and the thorium amide complex, [Th(NR)(NH)] (), were recorded. The spectrum for represents the first reported solid-state N NMR data for an actinide complex. The experimentally measured tensor spans are Ω = 847 ppm for and Ω = 237 ppm for . Both shielding tensors exhibit axial symmetry, which for is consistent with a local rotational symmetry of its N-labeled nitride ligand. For , the axial asymmetry can be rationalized by a quasi-free Th-NH bond rotation in the solid-state. Density functional theory calculations overestimate the tensor span somewhat for , but provide isotropic shifts in good agreement with both the solid-state and solution values for both complexes. Natural localized molecular orbital analyses of the nuclear shielding reveal that the larger tensor span in vs is primarily a consequence of more pronounced covalency of the σ(N-Th) bonds and large spin-orbit coupling due to significant Th 5f orbital contribution to those bonds, impacting the principal components of the shielding tensor perpendicular to the Th-N-Th axis. Overall, our analysis confirms the involvement of the 5f orbitals in Th-N multiple bonds and further demonstrates the value of solid-state NMR spectroscopy for interrogating actinide-ligand bonding.
记录了氮化钍配合物[K(18-冠-6)(THF)][(RN)Th(μ-N)Th(NR)]（，R = SiMe）和钍酰胺配合物[Th(NR)(NH)]（）的固态N NMR粉末谱。的谱图代表了首次报道的锕系元素配合物的固态N NMR数据。实验测得的张量范围对于为Ω = 847 ppm，对于为Ω = 237 ppm。两个屏蔽张量都表现出轴向对称性，对于而言，这与其N标记的氮化物配体的局部旋转对称性一致。对于，轴向不对称性可以通过固态中准自由的Th-NH键旋转来解释。密度泛函理论计算对的张量范围略有高估，但提供的各向同性位移与两种配合物的固态和溶液值都有很好的一致性。对核屏蔽的自然定域分子轨道分析表明，与相比，中较大的张量范围主要是由于σ(N-Th)键更强的共价性以及由于Th 5f轨道对这些键有显著贡献而导致的大自旋轨道耦合，影响了垂直于Th-N-Th轴的屏蔽张量的主分量。总体而言，我们的分析证实了5f轨道参与了Th-N多重键，并进一步证明了固态NMR光谱在研究锕系元素-配体键合方面的价值。
