Spin-Crossover Behavior of Hofmann-Type-Like Complex Fe(4,4’-bipyridine)Ni(CN)4·nH2O Depending on Guest Species

Kazumasa Hosoya,Takafumi Kitazawa,Masashi Takahashi,Shin-Ichi Nishikiori

doi:10.3390/magnetochemistry2010008

Kazumasa Hosoya, Takafumi Kitazawa + Show 2 more

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https://doi.org/10.3390/magnetochemistry2010008

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Abstract

A newly prepared metal complex Fe(4,4’-bipyridine)Ni(CN)4·nH2O, which was estimated to have a structure similar to the Hofmann-type clathrate host, changed its color from orange to deep orange and yellow on exposure to ethanol and acetone vapor, respectively, and the respective samples showed thermally induced two-step and one-step spin transitions.

Highlights

Spin-crossover FeII complexes are a promising source for new functional molecular switches because they can alternate between a high-spin (HS) and a low-spin (LS) state depending on the circumstances and show variations in magnetism, color and structure [1,2,3,4,5,6]
Many spin-crossover FeII complexes, especially those with polymeric structures, have been intensively studied because their polymeric linked structures enhance cooperative effects which work among the spin-crossover species resulting in spin transitions with hysteresis [7,8,9,10,11,12,13,14,15,16,17]
Because the single crystal X-ray diffraction method was inapplicable, the structural information was obtained from indirect methods such as EXAFS (Extended X-ray Absorption Fine Structure), IR spectroscopy and powder X-ray diffraction

Summary

Introduction

Spin-crossover FeII complexes are a promising source for new functional molecular switches because they can alternate between a high-spin (HS) and a low-spin (LS) state depending on the circumstances and show variations in magnetism, color and structure [1,2,3,4,5,6]. Many spin-crossover FeII complexes, especially those with polymeric structures, have been intensively studied because their polymeric linked structures enhance cooperative effects which work among the spin-crossover species resulting in spin transitions with hysteresis [7,8,9,10,11,12,13,14,15,16,17] If such FeII complexes gain another physical or chemical property besides spin-crossover, they would be even more fascinating as multi-functional materials. FeII(pyrazine)M’II(CN)4 ̈nH2O, where a spin transition with a higher transition temperature and a wider hysteresis loop were achieved [26,27,28] Based on this history, we tried to synthesize a new Hofmann-type-like FeII complex using a larger bidentate ligand 4,4’-bipyridine(bpy), expecting the resultant complex to function as a host and possess spin-crossover properties

Results and Discussion

Experimental Section

Conclusions