Kent Greggory T, Yu Xiaojuan, Wu Guang, Autschbach Jochen, Hayton Trevor W
Department of Chemistry and Biochemistry, University of California Santa Barbara Santa Barbara CA 93106 USA
Department of Chemistry, University at Buffalo, State University of New York Buffalo NY 14260 USA
Chem Sci. 2021 Oct 4;12(43):14383-14388. doi: 10.1039/d1sc04666g. eCollection 2021 Nov 10.
The reaction of [AnCl(NR)] (An = U, Th, R = SiMe) with generated lithium-3,3-diphenylcyclopropene results in the formation of [{(NR)}An(CH[double bond, length as m-dash]C[double bond, length as m-dash]CPh)] (An = U, ; Th, ) in good yields after work-up. Deprotonation of or with LDA/2.2.2-cryptand results in formation of the anionic allenylidenes, [Li(2.2.2-cryptand)][{(NR)}An(CCCPh)] (An = U, ; Th, ). The calculated C NMR chemical shifts of the C, C, and C nuclei in and nicely reproduce the experimentally assigned order, and exhibit a characteristic spin-orbit induced downfield shift at C due to involvement of the 5f orbitals in the Th-C bonds. Additionally, the bonding analyses for and show a delocalized multi-center character of the ligand π orbitals involving the actinide. While a single-triple-single-bond resonance structure (, An-C[triple bond, length as m-dash]C-CPh) predominates, the An[double bond, length as m-dash]C[double bond, length as m-dash]C[double bond, length as m-dash]CPh resonance form contributes, as well, more so for than for .
[AnCl(NR)]（An = U、Th，R = SiMe）与生成的锂-3,3-二苯基环丙烯反应，经过后处理后能以良好的产率生成[{(NR)}An(CH[双键，长度为m破折号]C[双键，长度为m破折号]CPh)]（An = U、；Th、）。用LDA/2.2.2-穴醚对或进行去质子化反应会生成阴离子亚联烯基，即[Li(2.2.2-穴醚)][{(NR)}An(CCCPh)]（An = U、；Th、）。对和中C、C和C原子核的C NMR化学位移计算结果很好地重现了实验确定的顺序，并且由于5f轨道参与Th-C键，在C处呈现出特征性的自旋轨道诱导的低场位移。此外，对和的键合分析表明涉及锕系元素的配体π轨道具有离域多中心特征。虽然单-三-单键共振结构（，An-C[三键，长度为m破折号]C-CPh）占主导，但An[双键，长度为m破折号]C[双键，长度为m破折号]C[双键，长度为m破折号]CPh共振形式也有贡献，对的贡献比对的更大。
