New Linear π‑Conjugated Diruthenium Compounds Containing Axial Tetrathiafulvalene-acetylide Ligands

Under the weak base conditions, diruthenium­(III) tetrakis-N,N′-dimethylbenzamidinate (DMBA) nitrate (Ru2(DMBA)4(NO3)2) reacted with electroactive tetrathiafulvalene acetylene ligands, HCC–TTF1 (5-ethynyl-2-(4,5-dimethyl-1,3-dithiol-2-ylidene)­benzo­[d]­[1,3]­dithiole) and HCC–TTF2 (2-(5-ethynylbenzo­[d]­[1,3]­dithiol-2-ylidene)­benzo­[d]­[1,3]­dithiole), to afford new compounds trans-Ru2(DMBA)4(CC–TTF1)2 (1) and trans-Ru2(DMBA)4(CC–TTF2)2 (2), respectively. The trans orientation and the planar nature of the ethynyltetrathiafulvalene ligands around the Ru2(III,III) core were supported by the single-crystal X-ray diffraction study of compound 1. Both compounds 1 and 2 and their TTF ligand precursors were characterized with the spectroscopic and voltammetric techniques, which revealed a minimal electronic interaction between the two TTF moieties within the same compound. The electronic structure of trans-Ru2(DMBA)4(CC–TTF)2 was analyzed based on a DFT calculation of a model compound, and the resultant distribution of valence MOs is consistent with the voltammetric results.在弱碱性条件下，四(N,N′-二甲基苯甲脒)二钌(III)硝酸盐(diruthenium(III) tetrakis-N,N′-dimethylbenzamidinate nitrate，化学式Ru₂(DMBA)₄(NO₃)₂)分别与电活性四硫富瓦烯(Tetrathiafulvalene, TTF)乙炔配体HC≡C–TTF₁（5-乙炔基-2-(4,5-二甲基-1,3-二硫杂环戊烯-2-亚基)苯并[d][1,3]二硫杂环戊烯）和HC≡C–TTF₂（2-(5-乙炔基苯并[d][1,3]二硫杂环戊烯-2-亚基)苯并[d][1,3]二硫杂环戊烯）反应，分别得到新型化合物反式-Ru₂(DMBA)₄(C≡C–TTF₁)₂（化合物1）与反式-Ru₂(DMBA)₄(C≡C–TTF₂)₂（化合物2）。通过对化合物1的单晶X射线衍射(single-crystal X-ray diffraction)分析，证实了Ru₂(III,III)核周围乙炔基四硫富瓦烯配体的反式取向与平面构型。采用光谱学与伏安法对化合物1、2及其TTF配体前驱体进行了表征，结果显示同一分子内两个TTF单元之间仅存在极弱的电子相互作用。基于模型化合物的密度泛函理论(Density Functional Theory, DFT)计算，对反式-Ru₂(DMBA)₄(C≡C–TTF)₂的电子结构进行了分析，所得价分子轨道(Molecular Orbital, MO)的分布结果与伏安测试结果一致。