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Partial spin crossover behaviour in a dinuclear iron(II) triple helicate.
Rosanna J Archer1, Chris S Hawes, Guy N L Jameson
1Department of Chemistry, University of Canterbury, Private Bag 4800, Christchurch, 8041, New Zealand.
Dalton Transactions (Cambridge, England : 2003)
|October 12, 2011
Summary
This study reports a dinuclear iron(II) helicate complex that exhibits reversible spin crossover behavior. The spin crossover temperature is influenced by the degree of hydration, offering insights into molecular magnetism.
Area of Science:
- Coordination Chemistry
- Materials Science
- Magnetochemistry
Background:
- Dinuclear iron(II) complexes are of interest for their magnetic properties.
- Spin crossover (SCO) phenomena in iron(II) complexes allow for switching between low-spin and high-spin states.
- Understanding the influence of solvent molecules on SCO behavior is crucial for designing functional materials.
Purpose of the Study:
- To synthesize and characterize a novel dinuclear Fe(II) triple helicate complex.
- To investigate the magnetic properties, specifically spin crossover behavior, of the complex.
- To explore the effect of hydration on the spin crossover transition temperature.
Main Methods:
- Synthesis of the dinuclear Fe(II) triple helicate complex [Fe(2)(L)(3)](ClO(4))(4).xH(2)O.
- Structural characterization using low-temperature X-ray diffraction.
- Magnetic susceptibility measurements over a temperature range of 4.5-300 K.
- Mössbauer spectroscopy at 4.5 K and 295 K.
Main Results:
- The complex exists as a [LS:HS] species at low temperatures.
- A reversible, single-step spin crossover occurs at one Fe(II) center at higher temperatures, forming a [HS:HS] species.
- The spin crossover transition temperature (T(1/2)(SCO)) varies with hydration level (x=1-4), ranging from 210 K to 265 K.
- Dehydration/hydration cycles are reversible, and the hydrated form can be recovered upon exposure to water vapor.
Conclusions:
- The dinuclear Fe(II) helicate exhibits hydration-dependent spin crossover behavior.
- This contrasts with a related acetonitrile solvate, highlighting the role of solvent in modulating magnetic properties.
- The findings provide a basis for designing switchable molecular materials based on spin crossover.
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