Synthesis And Characterization Of Cyano-bridged Cubic Iron Clusters With Spin Crossover Behavior

In recent years,there has been a great interest in the field of novel coordination compounds with spin crossover behavior due to their adjustable magnetic properties.Under the external stimuli such as light irradiation or changes in temperature or pressure,the spin state of the metal nuclear of these compounds can change from high-spin state to low-spin state,or vice versa.Therefore,these compounds may have great application prospects in the field of designing novel molecular switches,high-density information storage materials,new sensing materials and display devices for their ideal molecular bistability or multistabiliy.Spin crossover is most commonly observed in six-coordinate iron(?),iron(?)and cobalt(?)molecular complexes.Multinuclear coordination compounds with spin crossover behavior are expected to show better bistable and multistable.Up to now,research in this field is still very limited.The current situation,progress and significances of external stimuli-induced spin crossover were summarized in this paper.This work was devoted to the research of thermally induced spin crossover properties of cyanide-bridged iron clusters.Some iron clusters have been synthesized and characterized by using Fourier transform infrared spectrometer(FTIR),single-crystal X-ray diffraction,magnetic measurement and so on.We have synthesized a series of iron(?)cube clusters:[(Tp)4Fe?8(CN)12(Tpp)4],M+(?)[(TP)4Fe?8(CN)12(Tpp)4]·ClO4,M+(?)[(Tp)4Fe?8(CN)12(Tpp)4]·PF6(M+ = Na+,K+,Rb+,Cs+;Tp-= hydrotris(1-pyrazolyl)borate;Tpp = tris(2-pyridyl)phosphine),[(Tp)4Fe?8(CN)12(TppO)4],M+(?)[(Tp)4Fe?8(C-N)12(TppO)4]·PF6(M+ = K+,Rb+,Cs+;TppO = tris(2-pyridyl)phosphine oxide),and they show interesting spin crossover.Encapsulating different alkali cations changed the spin crossover of the clusters remarkably,and some of them show a two-step spin transition.These clusters will have potential applications in designing novel molecular switches and ion screening.