Kamilya Sujit, Ghosh Subrata, Mehta Sakshi, Mondal Abhishake
Solid State and Structural Chemistry Unit, Indian Institute of Science, Sir C. V. Raman Road, Bangalore 560012, India.
J Phys Chem A. 2021 Jun 10;125(22):4775-4783. doi: 10.1021/acs.jpca.1c02032. Epub 2021 Apr 23.
A series of three new cyanide-bridged [FeCo] molecular square complexes, namely, {[Fe(Tp*)(CN)][Co(L)]}(BF)·2DMF (L = bik (), bik* (), and vbik (); Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate, bik = bis(1-methyl-1-imidazol-2-yl)ketone, bik* = bis(1-ethyl-1-imidazol-2-yl)ketone, and vbik = bis(1-vinyl-1-imidazol-2-yl)ketone; DMF = dimethylformamide) were synthesized and characterized by single-crystal X-ray diffraction analyses and by magnetic, electrochemical, and spectroscopic measurements. Magnetic studies reveal that all three complexes exhibit temperature-induced metal-to-metal electron transfer (MMET) from a high-spin Co(II) center to a low-spin Fe(III) center, transforming a high-temperature paramagnetic {Fe-CN-Co} ground state into a low-temperature diamagnetic {Fe-CN-Co} state with a decrease in the temperature from 300 to 100 K. Complexes and show the interconversion of the paramagnetic {Fe-CN-Co} ground state into a diamagnetic {Fe-CN-Co} state in a single-step transition with values of 180 and 186 K, respectively, while a two-step MMET with value of 214 and 178 K was observed for complex .
合成了一系列三种新型氰基桥联的[FeCo]分子方形配合物，即{[Fe(Tp*)(CN)][Co(L)]}(BF)·2DMF（L = bik（ ）、bik*（ ）和vbik（ ）；Tp* = 氢三(3,5 - 二甲基吡唑 - 1 - 基)硼酸酯，bik = 双(1 - 甲基 - 1 - 咪唑 - 2 - 基)酮，bik* = 双(1 - 乙基 - 1 - 咪唑 - 2 - 基)酮，vbik = 双(1 - 乙烯基 - 1 - 咪唑 - 2 - 基)酮；DMF = 二甲基甲酰胺），并通过单晶X射线衍射分析以及磁性、电化学和光谱测量对其进行了表征。磁性研究表明，所有这三种配合物都表现出温度诱导的金属到金属电子转移（MMET），从高自旋Co(II)中心转移到低自旋Fe(III)中心，随着温度从300 K降至100 K，将高温顺磁性的{Fe - CN - Co}基态转变为低温抗磁性的{Fe - CN - Co}态。配合物 和 显示顺磁性的{Fe - CN - Co}基态在一步转变中分别以180 K和186 K的值转变为抗磁性的{Fe - CN - Co}态，而配合物 观察到两步MMET，值分别为214 K和178 K。
