Related Experiment Video
Updated: Nov 3, 2025
11:44
Using Cyclic Voltammetry, UV-Vis-NIR, and EPR Spectroelectrochemistry to Analyze Organic Compounds
Published on: October 18, 2018
27.0K
Valence tautomerism in a [2 × 2] Co4 grid complex containing a ditopic arylazo ligand
Nico M Bonanno1, Zackery Watts1, Cole Mauws2
1Department of Chemistry, Brock University, St. Catharines, ON L2S 3A1, Canada. mlemaire@brocku.ca.
Chemical Communications (Cambridge, England)
|June 1, 2021
Summary
This study reveals valence tautomerization in a cobalt-4 (Co4) grid complex, a rare phenomenon in such polynuclear structures. The complex exhibits unique magnetic properties in both solution and solid states.
Area of Science:
- Coordination Chemistry
- Magnetochemistry
- Materials Science
Background:
- Polynuclear metal complexes offer unique magnetic properties.
- Valence tautomerization is a rare phenomenon in coordination chemistry.
- Grid complexes provide a platform for studying complex magnetic behaviors.
Purpose of the Study:
- To synthesize and characterize a tetranuclear [2 × 2] cobalt grid complex.
- To investigate the structural and magnetic properties of the Co4 complex.
- To explore the occurrence of valence tautomerization in this grid system.
Main Methods:
- Synthesis of a tetranuclear [2 × 2] Co4 grid complex with a ditopic arylazo ligand.
- Variable temperature magnetic susceptibility experiments.
- Powder-pattern Electron Paramagnetic Resonance (EPR) spectroscopy.
Main Results:
- The complex consists of Co3+ ions and singly reduced trianion-radical ligands in solution at low temperatures.
- Evidence for valence tautomerization was observed in the solid state.
- This is the first reported instance of valence tautomerism in a [2 × 2] grid complex.
Conclusions:
- The Co4 grid complex exhibits distinct structural and magnetic properties.
- Valence tautomerization is demonstrated in the solid state, a rare occurrence for grid complexes.
- This finding expands the understanding of magnetic phenomena in polynuclear coordination compounds.
Related Concept Videos
02:42Valence Bond Theory
9.9K
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...
9.9K
02:45Valence Bond Theory
40.9K
Overview of Valence Bond Theory
40.9K
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
45.7K
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,...
45.7K
02:58Crystal Field Theory - Octahedral Complexes
28.6K
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...
28.6K
02:57Coordination Number and Geometry
17.2K
For transition metal complexes, the coordination number determines the geometry around the central metal ion. Table 1 compares coordination numbers to molecular geometry. The most common structures of the complexes in coordination compounds are octahedral, tetrahedral, and square planar.
17.2K
02:52Stereoisomerism
12.8K
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
12.8K