Modder Dieuwertje K, Batov Mikhail S, Rajeshkumar Thayalan, Sienkiewicz Andrzej, Zivkovic Ivica, Scopelliti Rosario, Maron Laurent, Mazzanti Marinella
Group of Coordination Chemistry, Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
Laboratoire de Physique et Chimie des Nano-objets, Institut National des Sciences Appliquées Cedex 4 31077 Toulouse France.
Chem Sci. 2022 Aug 31;13(38):11294-11303. doi: 10.1039/d2sc03592h. eCollection 2022 Oct 5.
Radical-bridged diuranium complexes are desirable for their potential high exchange coupling and single molecule magnet (SMM) behavior, but remain rare. Here we report for the first time radical-bridged diuranium(iv) and diuranium(iii) complexes. Reaction of [U{N(SiMe)}] with 2,2'-bipyrimidine (bpym) resulted in the formation of the bpym-bridged diuranium(iv) complex [{((MeSi)N)U}(μ-bpym)], 1. Reduction with 1 equiv. KC reduces the complex, affording [K(2.2.2-cryptand)][{((MeSi)N)U}(μ-bpym)], 2, which is best described as a radical-bridged U-bpym˙-U complex. Further reduction of 1 with 2 equiv. KC, affords [K(2.2.2-cryptand)][{((MeSi)N)U}(μ-bpym)], 3. Addition of AgBPh to complex 1 resulted in the oxidation of the ligand, yielding the radical-bridged complex [{((MeSi)N)U}(μ-bpym˙)][BPh], 4. X-ray crystallography, electrochemistry, susceptibility data, EPR and DFT/CASSCF calculations are in line with their assignments. In complexes 2 and 4 the presence of the radical-bridge leads to slow magnetic relaxation.
自由基桥联的二铀配合物因其潜在的高交换耦合和单分子磁体（SMM）行为而备受关注，但仍然很少见。在此，我们首次报道了自由基桥联的二铀（IV）和二铀（III）配合物。[U{N(SiMe)}]与2,2'-联嘧啶（bpym）反应生成了bpym桥联的二铀（IV）配合物[{((MeSi)N)U}(μ-bpym)]，即1。用1当量的KC还原该配合物，得到[K(2.2.2-穴醚)][{((MeSi)N)U}(μ-bpym)]，即2，它最好被描述为一种自由基桥联的U-bpym˙-U配合物。用2当量的KC进一步还原1，得到[K(2.2.2-穴醚)][{((MeSi)N)U}(μ-bpym)]，即3。向配合物1中加入AgBPh导致配体氧化，生成自由基桥联配合物[{((MeSi)N)U}(μ-bpym˙)][BPh]，即4。X射线晶体学、电化学、磁化率数据、电子顺磁共振和密度泛函理论/完全活性空间自洽场计算结果与它们的归属一致。在配合物2和4中，自由基桥的存在导致了缓慢的磁弛豫。
