A novel mixed-valence rigid molecular square [FeII3FeIIIL2(HL)2]3+ was constructed via self-assembly using bis(2-acetylpyridine) thiocarbazone (H2L) as both linker and reducing agent. Single crystal structure analysis shows that each cation is located at an inversion center with four iron atoms at the corners of a square with edge length Feâ¯Fe ca. 4.2 Ã
. Magnetic measurement exhibits that there is only one FeIII center in each of the tetranuclear squares. There is no significant difference of the coordinated bonds among the four iron centers, indicating that it is impossible to recognize the FeIII in the four iron centers of a square. Electrochemical measurement and UVâVISâNIR spectral studies demonstrate the RobinâDay class II behavior of the mixed-valence compound with appreciable ironâiron interaction. New rigid metallocyclic squares [Ni(HL)]44+, [Zn(HL)]44+ and [Cd(HL)]44+ were also assembled and structurally characterized for comparison. ESI-MS spectra reveal that the fragments of tetranuclear molecular squares are stable even in solution.
利用双(
2-乙酰基吡啶)
硫代卡唑酮(H2L)作为连接剂和还原剂,通过自组装构建了一种新型混价刚性分子方阵[FeII3FeIII
L2(HL)2]3+。单晶结构分析表明,每个阳离子都位于一个反转中心,四个
铁原子位于边长约为 Feâ¯Fe 的正方形的四角。4.2 à .磁性测量显示,每个四核正方形中只有一个 FeIII 中心。四个
铁中心之间的配位键没有明显的差异,这表明不可能在一个正方形的四个
铁中心中识别出 FeⅢ。电
化学测量和紫外、可见光、近红外光谱研究表明,这种具有明显
铁-
铁相互作用的混价化合物具有罗宾-戴第二类行为。为了进行比较,我们还组装了新的刚性
金属环方形化合物 [Ni(HL)]44+、[Zn(HL)]44+ 和 [Cd(HL)]44+,并对其进行了结构表征。ESI-MS 光谱显示,四核分子方阵的碎片即使在溶液中也是稳定的。