Water-Mediated Charge Transfer and Electron Localization in a Co3Fe2 Cyanide-Bridged Trigonal Bipyramidal Complex
Emily Hruska1, Quansong Zhu1, Somnath Biswas1
1Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States.
Journal of the American Chemical Society
|March 13, 2024
Summary
Environmental factors like temperature and solvents influence the spin states of molecular magnets. This study reveals how charge transfer and electron delocalization control these spin transitions, impacting molecular properties.
Area of Science:
- Coordination Chemistry
- Materials Science
- Spectroscopy
Background:
- Molecular paramagnets with cyanide bridges exhibit complex electronic behaviors.
- Understanding environmental effects on spin transitions is crucial for molecular electronics.
- Charge delocalization and localization influence magnetic and electronic properties.
Purpose of the Study:
- To investigate the impact of temperature and chemical environment on a pentanuclear molecular paramagnet.
- To elucidate the mechanisms of charge transfer and spin transitions in response to external stimuli.
- To correlate spectroscopic observations with theoretical calculations for a comprehensive understanding.
Main Methods:
- Element- and oxidation state-specific near-ambient pressure X-ray photoemission spectroscopy (NAP-XPS) to probe charge transfer.
- Second-order nonlinear vibrational spectroscopy (Sum Frequency Generation Vibrational Spectroscopy, SFG-VS) to detect symmetry changes.
- Density Functional Theory (DFT) calculations to support experimental findings.
Main Results:
- Temperature changes induce metal-to-metal charge transfer (MMCT) between cobalt and iron centers.
- Solvent presence (H-bonding) leads to charge localization (Robin-Day class I low spin state).
- Solvent removal promotes charge delocalization (Robin-Day class II/III high spin state) and MMCT.
- Reversible switching of the dipole moment observed, analogous to molecular multiferroics.
Conclusions:
- The chemical environment and solvation play a critical role in controlling charge and spin transitions.
- The molecular cluster exhibits reversible switching between localized and delocalized electronic states.
- Findings highlight the potential of such complexes for applications in molecular switches and multiferroic materials.
Related Concept Videos
02:42Valence Bond Theory
8.5K
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
8.5K
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
42.5K
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
42.5K
02:58Crystal Field Theory - Octahedral Complexes
26.4K
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
26.4K
03:45Formation of Complex Ions
23.6K
A type of Lewis acid-base chemistry involves the formation of a complex ion (or a coordination complex) comprising a central atom, typically a transition metal cation, surrounded by ions or molecules called ligands. These ligands can be neutral molecules like H2O or NH3, or ions such as CN− or OH−. Often, the ligands act as Lewis bases, donating a pair of electrons to the central atom. These types of Lewis acid-base reactions are examples of a broad subdiscipline called coordination...
23.6K
03:02Colors and Magnetism
11.7K
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
11.7K
02:51Metal-Ligand Bonds
20.8K
The hemoglobin in the blood, the chlorophyll in green plants, vitamin B-12, and the catalyst used in the manufacture of polyethylene all contain coordination compounds. Ions of the metals, especially the transition metals, are likely to form complexes.
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
20.8K