Stetsiuk Oleh, Petrusenko Svitlana R, Sorace Lorenzo, Lupan Alexandru, Attia Amr A A, Kokozay Vladimir N, El-Ghayoury Abdelkrim, Avarvari Narcis
MOLTECH-Anjou, UMR 6200, CNRS, UNIV Angers, 2 bd Lavoisier, 49045 ANGERS Cedex, France.
Department of Inorganic Chemistry, Taras Shevchenko National University of Kyiv, Volodymyrska str. 64/13, Kyiv 01601, Ukraine.
Dalton Trans. 2019 Aug 21;48(31):11966-11977. doi: 10.1039/c9dt02379h. Epub 2019 Jul 17.
The 3-Cl-6-amino-(2'-picolyl)-1,2,4,5-tetrazine ligand HL has been synthesized and structurally characterized. Its versatile coordination behavior has been evidenced through reactions with Cu(Hfac) and Cu(triflate) precursors, which provided mixed-valence bimetallic CuCu complexes [Cu(μ-Cl)(L)] 2 and [Cu(μ-triflate)(L)] 5. Changing the Cu(ii) precursor and the solvent leads to the formation of mononuclear octahedral Cu(ii) complexes [CuCl(HL)]·2CHCN 3 and [Cu(Hfac)(HL)] 4, in which only the amino-pyridine unit is involved in the coordination of the metal center. In contrast, in complexes 2 and 5, the ligands are deprotonated and bridge the metal centers as pyridine-amido-tetrazine fragments, while a bridging chloride or triflate ligand completes the coordination sphere of the metal ions. The Cu-Cu distances of 2.4313(4) Å in 2 and 2.5198(10) Å in 5 lie among the shorter values within mixed-valence bimetallic Cu complexes. Mixed-valence character is strongly supported by DFT calculations, showing the equal repartition of the unpaired electron between the two metal centers.
已合成并对3-氯-6-氨基-(2'-吡啶甲基)-1,2,4,5-四嗪配体HL进行了结构表征。通过与Cu(Hfac)和Cu(三氟甲磺酸盐)前体反应，证明了其多样的配位行为，这些反应生成了混合价态的双金属CuCu配合物[Cu(μ-Cl)(L)]₂和[Cu(μ-三氟甲磺酸盐)(L)]₅。改变Cu(ii)前体和溶剂会导致形成单核八面体Cu(ii)配合物[CuCl(HL)]·2CHCN₃和[Cu(Hfac)(HL)]₄，其中只有氨基吡啶单元参与金属中心的配位。相比之下，在配合物2和5中，配体去质子化并作为吡啶-酰胺基-四嗪片段桥连金属中心，而桥连的氯或三氟甲磺酸盐配体则完善了金属离子的配位球。配合物2中Cu-Cu距离为2.4313(4) Å，配合物5中为2.5198(10) Å，处于混合价态双金属Cu配合物中较短的值范围内。密度泛函理论计算有力地支持了混合价态特征，表明未成对电子在两个金属中心之间平均分配。
