De Siddhartha, Mondal Arpan, Tang Jinkui, Layfield Richard A
Department of Chemistry, School of Life Sciences, University of Sussex, Brighton, BN1 9RH, UK.
State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, P.R. China.
Angew Chem Int Ed Engl. 2025 Nov 3;64(45):e202516323. doi: 10.1002/anie.202516323. Epub 2025 Sep 14.
f-Element organometallic chemistry is dominated by cyclopentadienyl ligands. In contrast, isoelectronic metallole ligands with the general formula [ECR], where E is a heavier group 14 element, are rare in the f-block, particularly stannole ligands. Here, we describe the synthesis of the dimetallic stannole complexes [(η-Cp)M(η-Cp)] (1 ; M = Y, Gd, Dy; Cp = [SnC-2,5-(SiMe)-3,4-Me], Cp = [1,2,4-C BuH]), which form by virtue of Sn→M dative bonds. One-electron reduction of 1 with KC/2.2.2-cryptand produces the mono-anionic complexes [{(η-Cp)M(η-Cp)}] (2), and two-electron reduction gives di-anionic [{(η-Cp)M(η-Cp)}] (3) as [K(2.2.2-crypt)] salts. Studies of the stannole complexes using crystallography, UV/vis and EPR spectroscopy, magnetometry and computational methods reveal that the reduction steps generate tin-tin bonds through population of a delocalized molecular orbital that spans the {MSn} rings, with attendant dearomatization of the stannole rings. Complexes 2 are the first tin-radical ligands bound to rare earth elements. Spin density calculations of 2 and 2 reveal significant build-up of unpaired spin on the tin atoms, with magnetic measurements on 2 yielding an unprecedentedly large tin-gadolinium exchange coupling constant of -112 cm (-2J formalism).
f 区元素有机金属化学以环戊二烯基配体为主导。相比之下，通式为[ECR]的等电子金属杂环配体（其中 E 是较重的第 14 族元素）在 f 区中很少见，尤其是锡杂环配体。在此，我们描述了双金属锡杂环配合物[(η-Cp)M(η-Cp)]（1；M = Y、Gd、Dy；Cp = [SnC-2,5-(SiMe)-3,4-Me]，Cp = [1,2,4-C BuH]）的合成，其通过 Sn→M 配位键形成。用 KC/2.2.2-穴醚对 1 进行单电子还原生成单阴离子配合物[{(η-Cp)M(η-Cp)}]（2），双电子还原则得到二阴离子[{(η-Cp)M(η-Cp)}]（3），以[K(2.2.2-穴醚)]盐的形式存在。使用晶体学、紫外/可见光谱和电子顺磁共振光谱、磁学测量以及计算方法对锡杂环配合物进行的研究表明，还原步骤通过填充跨越{MSn}环的离域分子轨道生成锡-锡键，同时锡杂环发生去芳构化。配合物 2 是首个与稀土元素结合的锡自由基配体。对 2 和 2 的自旋密度计算表明锡原子上未成对自旋显著积累，对 2 的磁学测量得到了前所未有的大的锡-钆交换耦合常数-112 cm（-2J 形式）。
