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On-line Analysis of Nitrogen Containing Compounds in Complex Hydrocarbon Matrixes
Published on: August 5, 2016
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Selective Isomer Formation and Crystallization-Directed Magnetic Behavior in Nitrogen-Confused C-Scorpionate
James R Gardinier1, Kristin J Meise1, Fathiya Jahan1
1Department of Chemistry , Marquette University , Milwaukee , Wisconsin 53201-1881 , United States.
Inorganic Chemistry
|June 29, 2019
Summary
This study synthesized a new iron complex, [Fe(HL*)2](OTf)2, to investigate its magnetic properties and spin crossover (SCO) behavior. Six crystalline forms were identified, with some exhibiting SCO at lower temperatures after desolvation.
Area of Science:
- Coordination Chemistry
- Materials Science
- Magnetochemistry
Background:
- Spin crossover (SCO) is a phenomenon in transition metal complexes where a change in spin state (low spin to high spin) is triggered by external stimuli.
- Iron(II) complexes are well-studied SCO materials, with ligand design playing a crucial role in tuning SCO properties.
- The parent complex [Fe(HL)2](OTf)2 exhibits SCO above room temperature, making it a benchmark for comparison.
Purpose of the Study:
- To synthesize and characterize a new semibulky iron(II) complex, [Fe(HL*)2](OTf)2 (1).
- To compare the magnetic properties, specifically spin crossover behavior, of complex 1 with its parent analog.
- To explore the influence of crystallization conditions on the formation of different crystalline forms and their SCO properties.
Main Methods:
- Synthesis of the iron(II) complex [Fe(HL*)2](OTf)2 (1).
- Crystallization under various conditions (solvent, temperature, diffusion methods) to obtain different crystalline forms.
- Characterization of crystalline forms using techniques such as X-ray diffraction and elemental analysis.
- Magnetic property measurements to determine spin crossover behavior.
Main Results:
- Six distinct crystalline forms of complex 1 were successfully prepared by controlling crystallization parameters.
- The trans isomer of complex 1 was isolated in various solvated forms (LS trans-1·2CH3CN and HS trans-1·4CH3CN).
- Solvate-free forms (trans-1, trans-1·CH3CN, cis-1, and co-1) exhibited spin crossover below 250 K, while solvated forms did not undergo SCO until desolvation.
Conclusions:
- The semibulky ligand HL* influences the spin crossover behavior of the iron(II) complex.
- Crystallization conditions critically affect the formation of different solvates and isomers, impacting SCO properties.
- Desolvation is necessary for the spin crossover phenomenon to occur in certain crystalline forms of complex 1.
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