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Spin crossover in tetranuclear cyanide-bridged iron(II) square complexes: a theoretical study
Ekaterina M Zueva1, Elmira R Ryabikh, Andrey M Kuznetsov
1Department of Inorganic Chemistry, Kazan State Technological University, 68 K. Marx Street, 420015 Kazan, Russia. zueva_ekaterina@mail.ru
Inorganic Chemistry
|January 29, 2011
Summary
Density functional theory (DFT) reveals that cyanide-bridged iron(II) complexes exhibit one-step spin crossover due to weak elastic coupling. Crystal packing can induce two-step transitions in specific cases.
Area of Science:
- Coordination Chemistry
- Materials Science
- Computational Chemistry
Background:
- Spin crossover (SCO) is a phenomenon where iron(II) complexes switch between low-spin (LS) and high-spin (HS) states.
- Cyanide-bridged iron(II) tetranuclear square complexes are investigated for their SCO properties.
Purpose of the Study:
- To analyze spin crossover behavior in six cyanide-bridged iron(II) tetranuclear square complexes.
- To characterize the energetics and structures of different spin-state isomers ([LS-LS], [HS-LS], [HS-HS]).
- To evaluate the elastic coupling and exchange interactions between iron ions.
Main Methods:
- Density Functional Theory (DFT) calculations were employed.
- Energetic and structural characterization of spin-state isomers.
- Analysis of elastic coupling and exchange coupling strengths.
Main Results:
- The mixed [HS-LS] spin state energy is consistently near the midpoint between homogeneous states, favoring one-step transitions.
- Weak elastic coupling between iron centers facilitates the one-step SCO.
- Crystal packing effects were identified as a cause for two-step spin transitions in one complex.
- Exchange coupling in the [HS-HS] state was quantified.
Conclusions:
- The studied iron(II) complexes generally exhibit favorable conditions for one-step spin crossover.
- Elastic coupling strength is a critical factor determining the SCO mechanism.
- Crystal packing can significantly influence SCO behavior, potentially leading to multi-step transitions.
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