Queen Joshua D, Rajabi Ahmadreza, Goudzwaard Quinn E, Yuan Qiong, Nguyen Dang Khoa, Ziller Joseph W, Furche Filipp, Xi Zhenfeng, Evans William J
Department of Chemistry, University of California Irvine 92697 California USA
Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University Beijing 100871 China
Chem Sci. 2024 Aug 30;15(39):16069-78. doi: 10.1039/d4sc03977g.
Although there are few reduced dinitrogen complexes of scandium, this metal has revealed a new structural type in reductive dinitrogen chemistry by reduction of bis(pentamethylcyclopentadienyl) scandium halides under N. Reduction of (Cp* = CMe) with potassium graphite (KC) under dinitrogen generates the dark blue paramagnetic complex , 1. This end-on bridging (N[double bond, length as m-dash]N) complex is a diradical with a magnetic moment of 2.8 . Upon further reduction of 1 with KC, the orange diamagnetic trimetallic complex , 2, is obtained. This complex has an unprecedented structure in which two side-on bridging (N[double bond, length as m-dash]N) ligands are bound to the central (Cp*Sc) moiety. Complex 2 can also be obtained directly from reduction of or a mixture of and with KC. The reaction of with KC in the presence of 18-crown-6 or 2.2.2-cryptand affords 2 along with small amounts of , 3, which is green at room temperature and purple at low temperature and displays a mixture of side-on and end-on bridging isomers in the crystal structure collected at -180 °C. Density functional theory (DFT) calculations are consistent with a triplet ground state for the end-on complex 1 and singlet ground states for the side-on complexes 2 and 3.
尽管钪的二氮配合物较少，但这种金属在还原二氮化学中通过在氮气氛围下还原双（五甲基环戊二烯基）钪卤化物揭示了一种新的结构类型。在氮气氛围下用钾石墨（KC8）还原（Cp* = C5Me5）得到深蓝色顺磁性配合物 1。这种端基桥连（N≡N）配合物是一种磁矩为 2.8 的双自由基。用 KC8 进一步还原 1 时，得到橙色抗磁性三金属配合物 2。该配合物具有前所未有的结构，其中两个侧基桥连（N≡N）配体与中心（CpSc）部分相连。配合物 2 也可以直接由（CpScCl2）或（CpScCl2）与（CpScNMe2）的混合物用 KC8 还原得到。在 18 - 冠 - 6 或 2.2.2 - 穴醚存在下，（Cp*ScCl2）与 KC8 的反应得到 2 以及少量的 3，3 在室温下为绿色，低温下为紫色，并且在 - 180°C 收集的晶体结构中显示出侧基桥连和端基桥连异构体的混合物。密度泛函理论（DFT）计算与端基配合物 1 的三重基态以及侧基配合物 2 和 3 的单重基态一致。
